Skip to main content
NCBI home page
Food Chemistry: X logoLink to Food Chemistry: X
. 2026 Jan 5;33:103497. doi: 10.1016/j.fochx.2026.103497

Integrated intelligent sensory and metabolomics elucidate the changes in sensory quality and metabolic profile during post-ripening of ‘Cuixiang’ kiwifruit

Shihan Bao a,1, Xinyi Li a,1, Guoqiang Zhang b, Runting Han a, Yongwu Li c, Xiangyu Sun d, Tingting Ma a,⁎
PMCID: PMC12816841  PMID: 41567561

Abstract

The evolution of sensory qualities, volatile and non-volatile metabolites of ‘Cuixiang’ kiwifruit during post-ripening were analyzed. Both human and intelligent sensory evaluation revealed that at 20 ± 1 °C and 90 % relative humidity, the color, taste, texture and aroma of ‘Cuixiang’ peaked at 11 d of post-ripening, signifying its best consumption window period. Volatile metabolomic indicated that the loss of greenness odour persisted throughout the post-ripening period, manifesting as a sharp decline in isobutyl isovalerate, 2,6-dimethyl-5-heptenal, E-3-hexenyl acetate and 2-nonanol, while the contents of benzyl benzoate, 3(2H)-furanone-4-methoxy-2,5-dimethyl, methyl methacrylate, methyl benzoate, methyl hexanoate and methyl caprate significantly increased, contributing to the richness of fruity, sweet and floral aroma. Totally 238 differentially accumulating metabolites were identified by non-volatile metabolomic. Key metabolites responsible for the multiple changes during post-ripening were screened, including elevated sugar-acid ratios, amino acid and lipid degradation, total phenol accumulation, and the initial rise followed by a decline in terpenoid content.

Keywords: Post-harvest ripening, Aroma, Taste, Volatile metabolites, Non-volatile metabolites

Graphical abstract

Unlabelled Image

Open in a new tab

Highlights

  • •

    Combined application and analysis of intelligent and human sensory evaluation.

  • •

    Volatile and non-volatile metabolomics show metabolites changes during post-ripening.

  • •

    ‘Cuixiang’ has less greenness and more fruity, sweet, floral aroma in post-ripening.

  • •

    Metabolites causing sensory attribute changes such as sugar-acid ratio are identified.

1. Introduction

Kiwifruit (Actinidia spp.) is a fruit of great commercial value. In recent years, China has led the world in cultivation area and production (Lan et al., 2022), and has cultivated many new and superior varieties, such as ‘Hongyang’, ‘Donghong’ and ‘Cuixiang’. Among these, the variety ‘Cuixiang’ (Actinidia deliciosa cv. Cuixiang) has rapidly emerged as the primary cultivated variety in Shaanxi Province, China's core production area, since its successful independent breeding in China in 2008. Its output in Zhouzhi County alone has reached 520,000 tons, with variety's value amounting to 4.23 billion yuan (Li et al., 2024), demonstrating significant industrial status, economic benefits and social value. The core competitiveness of ‘Cuixiang’ lies in its outstanding sensory quality. Its flesh is emerald green, with a higher content of soluble sugar, a sweet and juicy taste, and a unique and refreshing flavor (Wang, Qiu, & Zhu, 2021; Wang et al., 2024; Yang et al., 2024). Therefore, it is highly favored by consumers, and its market acceptance and purchase rate rank among the top of all varieties. As a respiratory climacteric fruit, kiwifruit undergoes the post-ripening process after harvest, a stage that is critical for the formation of commercial qualities including texture, flavor and aroma, and kiwifruit with suitable post-maturation is ideal for consumption. However, the post-ripening process is difficult to control, and kiwifruit is highly susceptible to rapid over-ripening after the edible softening stage, making it more prone to pathogen colonization, nutrient depletion, taste deterioration and the production of undesirable flavors such as alcoholic and musty flavors, ultimately reducing consumer acceptance (Wang et al., 2023; Yan, Chen, Zhao, Yao, & Ding, 2023).

The ‘Cuixiang’ variety has an early harvest season when environmental temperatures are relatively high (Wang et al., 2021). Combined with its unique pre-harvest black spot disease (Yang et al., 2022) and thin skin prone to mechanical damage (Yang et al., 2024), its post-ripening process develops faster and is more difficult to control than other varieties, resulting in poorer storability and a higher susceptibility to overstock and rot. This issue not only causes consumers to lack scientific basis for determining the optimal consumption period, but also severely restricts the cross-regional transportation and large-scale trading of ‘Cuixiang’, becoming the key bottleneck that hinders its upgrade from a ‘primary cultivated variety’ to a ‘major trading variety’. Numerous factors contribute to the difficulty in regulating the post-ripening process of ‘Cuixiang’, and the core one lies in the fact that the dynamic patterns of quality and their underlying regulatory mechanisms during this period remain unclear. Although our previous study investigated changes in texture and cell microstructure during the post-ripening of ‘Cuixiang’ (Li et al., 2024), systematic research on the post-ripening transformation mechanism of its most critical varietal advantage, sensory quality, remains lacking. In contrast, the ‘Hayward’ selected in New Zealand has its post-ripening quality formation and regulation mechanism fully understood (Huan et al., 2020; Wang, Martin, McAtee, Schaffer & Burdon, 2024; Yang et al., 2024), which has laid a scientific foundation for the establishment of its post-harvest preservation, storage, and transportation technology system, while also providing crucial support for its emergence as a mainstream variety in global trade. Therefore, conducting systematic research on the sensory quality and metabolic mechanisms during the post-ripening process of ‘Cuixiang’ holds distinct varietal specificity and urgent industrial relevance. This will provide theoretical support for its post-harvest production practices, thereby propelling this premium domestic variety into the mainstream international trade market.

Human sensory evaluation can reflect the real sense experience of fruit under actual consumption conditions, with the advantages of simplicity, ease of operation and practicality (Bao et al., 2023). However, due to subjectivity and poor reproducibility, it is no longer used as the only method of sensory evaluation. With the development of bionic sensors techniques, intelligent sensory technologies including electronic nose (E-nose), electronic tongue (E-tongue) and electronic eye have been widely used in fruit sensory quality testing. With the advantages of objectivity, speed and reproducibility, they facilitate the provision of clearer information about the sensory characteristics of fruit and their products (Chai, Liao, Li, & Liu, 2022; Lan et al., 2023). Therefore, the combination of human and intelligent sensory technologies can more comprehensively analyze the changes in sensory qualities of ‘Cuixiang’ during post-ripening. Volatile and non-volatile metabolomics, which are characterized by high sensitivity, accurate quantitative, wide coverage and large number of assays, are widely used in the research of food nutrition, fruit development and the evaluation of endogenous plant constituents (Dadwal, Aroor, Joshi, & Gupta, 2024). As powerful tools to study fruit quality changes during post-ripening, they contribute to identify the corresponding substances basis for the sensory phenotypic changes (Zhan et al., 2025).

By integrating human sensory evaluation with intelligent sensory technology, this study systematically analyzed the changes of odour, taste and color of ‘Cuixiang’ kiwifruit during the 13-day post-ripening process. The dynamic evolution patterns of metabolites during this process were also comprehensively revealed through volatile and non-volatile metabolomics, and the key metabolites underlying the formation of sensory qualities were further identified by multi-omics correlation analysis. The findings of this study could first guide consumers in scientifically identifying the optimal consumption stage of ‘Cuixiang’ kiwifruit; additionally, provide a theoretical basis for the development of post-ripening and storage control technologies, and ultimately help ‘Cuixiang’ break through industry bottlenecks and upgrade to a mainstream global trade variety.

2. Materials and methods

2.1. Kiwifruit samples

The commercially mature ‘Cuixiang’ kiwifruit was picked in Zhouzhi County, Shaanxi Province, China (34°09′49.04”N, 108°13′19.75″E), with harvesting conditions of 125.87 ± 1.75 N firmness, 7.32 ± 0.17°Brix total soluble solids (TSS) and 21.04 ± 1.45 % dry matter content (Table S1). 750 kiwifruits were picked from fifteen trees and mixed, which were then divided into three groups averagely to constitute three biological replicates. Each biological replicate containing 250 fruits was packed in a carton and stored in a thermostatic incubator at 20 ± 1 °C and 90 % relative humidity (RH) to simulate the sales environment (Li et al., 2024; Yang et al., 2024). At 2-day intervals, 90 kiwifruits were sampled and designated as D1-D13, with 30 fruits drawn from each replicate, while firmness (GY-4-J, Tuopuyun, Zhejiang, China) and TSS (PAL-1, ATAGO, Tokyo, Japan) were monitored (Table S1) until overripe. Human sensory evaluation and color characteristics test each consumed 10 fruits, and the remaining 10 fruits were homogenized, frozen in liquid nitrogen and stored at −80 °C for E-nose, E-tongue, volatile and non-volatile metabolites analyses. The whole sampling process were shown in Fig. S1.

2.2. Human sensory evaluation

A sensory panel was established with ten evaluators (five males and five females, aged 20–40 years) recruited from the College of Food Science and Engineering, Northwest A&F University, who had at least 1 year of experience in kiwifruit sensory evaluation. All evaluators were semi-trained with completion of 4 sessions of kiwifruit specific sensory training (1 h per session) before the experiment, to recognize typical sensory attributes of kiwifruit, unify the consensus on definitions of each sensory attribute and their sub factors, and standardize the operation of the 9-point hedonic scale, ensuring that the evaluators could provide accurate, consistent and repeatable sensory data. The standardized definitions for the five sensory attributes were as follows. Color: the comprehensive visual color characteristics of kiwifruit slices, which comprised the uniformity of flesh color distribution, greenness, yellowness and browning status, reflecting fruit ripeness and oxidation state. Appearance: the surface morphology and structural characteristics of kiwifruit slices, which comprised the degree of flesh tissue dehydration and shriveling, the state of rotting and the level of cellular water-soaking, reflecting the freshness and integrity of the fruit. Texture: the physical structural characteristics of kiwifruit slices perceived through oral mastication, which comprised firmness, juiciness and mealiness, reflecting the mouthfeel of the fruit. Taste: the taste sensation produced when kiwifruit slices stimulated the taste buds in the mouth, which comprised sweetness, acidity, astringency and alcoholic taste, reflecting the palatability of the fruit. Aroma: the volatile characteristics of the kiwifruit slices perceived through nasal olfaction, which comprised fruity aroma, herbal aroma and fermented smell, reflecting the intensity and freshness of the fruit's flavor.

At each post-ripening stage, 10 kiwifruits were allocated from each biological replicate, yielding a total of 30 kiwifruits for sensory evaluation per stage. A transverse slice (approximately 3 g) encompassing the central core, seed zone and flesh from the equatorial section of each fruit was obtained, and each evaluator could receive a total of three such slices. All sample slices were placed in transparent plastic cups, labeled with randomly generated three-digit codes, and equilibrated at a constant room temperature (25 °C) for 10 min to ensure the same temperature, before they were presented to the panel in a random order. After comprehensively assessing the synergistic performance of sub factors under each sensory attributes, the panel condensed their perception into a single hedonic score reflecting overall preference for that attribute. Specially, the panel rated the preference of the samples across five attributes: color (uniformity, greenness, yellowness, browning), appearance (shriveling, rotting, water-soaking), texture (firmness, juiciness, mealiness), taste (sweetness, acidity, astringency, alcoholic taste), aroma (fruity aroma, herbal aroma, fermented smell) and overall acceptability (comprehensive preference based on the above five attributes). And the 9-point hedonic scale was employed, where 9 meant “like extremely” and 1 meant “dislike extremely” (Huang et al., 2025).

As ethical approval of sensory evaluation was not required by national laws, the exemption from ethics committee approval was obtained. The appropriate protocols for protecting the rights and privacy of participants were utilized during the execution of the research, such as no coercion to participate, full disclosure of study requirements and risks, consent of all evaluators before the study, and ability to withdraw from the study at any time. All panelists involved in the sensory analysis gave their informed consent prior to participation.

2.3. Color characteristics analysis

After cutting the kiwifruit along its equatorial plane, randomly select eight test points from the flesh part on the equatorial cross-section for the immediate color characteristics analysis. Analysis was conducted using a CS-820 colorimeter (Caipu Co. Ltd., Hangzhou, China) in total reflection mode and CIELAB color space, which was previously calibrated with a standard white plate. The brightness (L*), red-greeness (a*), yellow-blueness (b*), color saturation (C*) and chromaticity angle (h°) were recorded and the color difference (ΔE) was calculated taking samples stored 1 d as control.

2.4. E-nose analysis

The flavor profile was determined using a PEN-3 E-nose (Airsense Analytics, Schwerin, Germany) with reference to Lan et al. (2023). Table S2 showed the specific response information of the sensors. 5 g kiwifruit homogenate was equilibrated at 25 °C for 10 min in the headspace vial before detection. The E-nose equipment was set as follows: carrier gas flow rate of 300 mL min−1, washing time of 300 s, detection time of 60 s, and the detection data of 54–59 s were selected for analysis.

2.5. E-tongue analysis

Astree E-tongue (Alpha M.O·S, Toulouse, France) consisting of six sensors (ZZ, CA, BA, GA, BB and JB) was used to identify the taste profile of ‘Cuixiang’, with sensors response information presented in Table S3. 20 g kiwifruit homogenate was diluted five-fold with distilled water and filtered by 0.45 μm filter membrane for measurement. Each measurement consisted of 10 s of ultrapure water rinsing and 120 s of testing, using the value generated at the last 7 s as the final output value.

2.6. Analysis of volatile metabolites

A solid-phase microextraction head coupled with GC–MS/MS approach was used to analyze the volatile organic compounds (VOCs) in ‘Cuixiang’ during post-ripening (Lan et al., 2022). 500 mg of the samples were placed in headspace vials containing 2 mL saturated NaCl solution and 10 μL internal solution (3-hexanone-2,2,4,4-d4, 50 μg mL−1). The vials were incubated at 60 °C for 5 min, and then extracted by the aging 120 μm DVB/CWR/PDMS fiber (Agilent, CA, USA) for 15 min. Subsequently, the fiber was inserted into the GC injection port for 5 min at 250 °C to desorb.

The qualification and quantification of VOCs were performed on a GC–MS/MS system (8890-7000D, Agilent, CA, USA) equipped with a DB-5MS capillary column. The carrier gas was high-purity helium at a constant flow rate of 1.2 mL min−1, the temperature of the injection port was 250 °C, and the non-shunt mode was selected. The temperature program was: 40 °C for 3.5 min, increasing to 100 °C, 180 °C and 280 °C at 10 °C·min−1, 7 °C·min−1 and 25 °C·min−1, respectively, finally holding at 280 °C for 5 min. Mass spectrometry was performed in electron ionization mode by selected ion monitoring at 70 eV ionization energy. The quadrupole mass detector, ion source, and transfer line temperatures were set at 150 °C, 230 °C and 280 °C, respectively. The mixture of n-alkanes (C8-C20) was measured using the same temperature program to calculate retention index (RI). RI, retention time (RT) and mass spectrum information were matched with NIST 17 and self-built MS2T database to identify VOCs. The construction and validation of MS2T were thoroughly described by Yuan et al. (2022). Quantification of VOCs was performed using the internal standard method. And the concentration of target VOCs were calculated based on the ratio of the peak area of their quantitative ions to that of the internal standard, which were expressed by μg g−1 fresh weight.

2.7. Analysis of non-volatile metabolites

Non-volatile metabolites in ‘Cuixiang’ kiwifruit during post-ripening were analyzed using a UPLC-electrospray ionization-MS/MS system (UPLC, ExionLC™ AD; MS/MS, Applied Biosystems 4500 QTRAP; MA, USA). Each group contained three biological replicates, and mixed samples served as quality control samples. Samples were freeze-dried, ground to powder, and extracted with 70 % methanol aqueous solution (v/v). After centrifugation, the supernatant was filtered and used for assay. The specific UPLC and MS/MS conditions referred to the description of Huang, Zhang, et al., 2025, with the injection volume modified to 4 μL. The metabolites were qualitatively analyzed based on MassBank and self-built MS2T database through comparing RT and secondary mass spectrometry information including fragmentation patterns and m/z values. The construction and validation of MS2T were thoroughly described by Chen et al. (2013). The quantification of metabolites was accomplished using the MRM mode of triple quadrupole mass spectrometry, to obtain the characteristic fragment ions for each substance and eliminate the interference of non-target ions. And the chromatographic peak area corresponding to the characteristic fragment ions was used to indicate the relative content of the corresponding substance.

2.8. Statistical analysis

Microsoft Excel 2023 was used for data analysis and visualization. SPSS 20 (IBM, Armonk, New York, USA) and Origin 2023 (Originlab, Massachusetts, USA) were used for ANOVA and Duncan's multiple range test, principal components analysis (PCA), linear discriminant analysis (LDA), hierarchical cluster analysis (HCA), K-means clustering and their visualization. The differential volatile metabolites (DVMs) were screened with the following conditions: fold change of variance (FC) ≥2 or ≤ 0.5, and variable projection importance (VIP) of orthogonal partial least squares discriminant analysis (OPLS-DA) ≥1. The differential accumulated non-volatile metabolites (DAMs) were screened with the following conditions: FC ≥2 or ≤ 0.5, VIP of OPLS-DA ≥1 and p-value of t-test <0.05. FC calculation, OPLS-DA and t-test for screening DVMs and DAMs were conducted on MetWare cloud platform (https://cloud.metware.cn). All data were expressed as mean ± standard deviation with three biological replicates.

3. Results and discussion

3.1. Human sensory evaluation

Food perception is the combination of human senses and brain activities, and human sensory evaluation can reflect the overall and true sensory characteristics of food (Jiang, Ni, Chen, & Liu, 2021). The sensory scores of ‘Cuixiang’ during post-ripening were shown in Fig. 1A. Appearance scores tended to decrease during the whole post-ripening period, ranging from 7 to 9 points, with some wrinkling of the skin at the end of post-ripening, but no rot or mould (Fig. 1C). In terms of taste, the fruit tasted sour and numb within 1–5 d and scored below 5 points. As post-ripening progressed, the fruit tasted significantly sweeter with reduced acidity, and scores gradually increased and reached the peak of 8.50 at 11 d, indicating the best sweet-sour palatability. The color scores firstly increased with the progress of post-ripening, peaking at 11 d and then declining. Consistent with the changes in color and taste scores, aroma and texture scores also increased with post-ripening, peaked at 11 d and then decreased.

Fig. 1.

Fig. 1

Open in a new tab

Individual scores (A) and overall acceptability (B) of human sensory evaluation of ‘Cuixiang’ kiwifruit at different post-ripening stages. Photograph of fruit appearance during post-ripening, (C). Chromaticity distribution map of fruit, (D). Error bars represented the standard deviation of the ten sensory evaluators. Different small letters represented significant differences (p < 0.05) based on Duncan's multiple range test.

The overall acceptability were shown in Fig. 1B. The highest score was 8.25 at 11 d, when the color, aroma, taste, and texture all reached their peak. Thus kiwifruit stored for 11 d had bright color, rich aroma, sweet-sour palatability and moderate texture, which was the best consumption window for ‘Cuixiang’ kiwifruit under conditions of 20 ± 1 °C and 90 % RH. Taking ‘Longcheng No.2’ as samples, Xiong, Sun, Tian, Xu, and Jiang (2023) also observed that the changes of appearance, aroma, flavor, texture and total score showed a trend of first increasing and then decreasing during post-ripening. In addition, Fig. 1B showed that the overall acceptability of kiwifruit decreased at 13 d, when compared to 11 d, the color became darker, the odour was mildly unpleasant, the texture was excessively soft and inelastic, and the taste had a slightly alcoholic flavor, implying that the kiwifruit had already reached the overripe stage.

3.2. Color characteristics analysis

As shown in Fig. 1D and Table 1, ‘Cuixiang’ at 1–3 d had the smallest values of a* and the largest values of b*, L* and C*, with yellowish-green flesh, bright color and high saturation. As post-ripening progressed to 5–9 d, the a* value gradually increased and the b* value decreased, indicating that the green and yellow color in kiwifruit faded noticeably, and the flesh converted from yellowish-green to green. Within 11–13 d, the a* value increased significantly, while the b*, L* and C* values decreased significantly, the color and lustre became darker, and the flesh turned dark green. ΔE value was significantly higher, and the color changes were obvious compared with 1 d.

Table 1.

Color indices of ‘Cuixiang’ kiwifruit during post-ripening.

Storage time/d L* a* b* c* h° ∆E
1 62.70 ± 1.59a −7.08 ± 0.26e 28.74 ± 1.01a 29.56 ± 1.05a 103.54 ± 0.44a
3 62.58 ± 1.46a −7.04 ± 0.16e 28.70 ± 1.12a 29.56 ± 1.10a 103.79 ± 0.52a 1.41 ± 1.04f
5 60.37 ± 1.61b −6.53 ± 0.22d 26.73 ± 0.97b 27.52 ± 0.98b 103.73 ± 0.34a 3.36 ± 1.32e
7 53.96 ± 1.91c −6.41 ± 0.42cd 25.96 ± 1.79bc 26.74 ± 1.83bc 103.87 ± 0.52a 9.25 ± 2.38d
9 51.21 ± 1.98d −6.07 ± 0.39c 24.72 ± 1.28c 25.46 ± 1.32c 103.76 ± 0.51a 12.25 ± 2.13c
11 43.35 ± 1.09e −4.21 ± 0.47b 17.19 ± 1.63d 17.71 ± 1.62d 103.89 ± 1.55a 22.74 ± 1.61b
13 42.30 ± 1.72e −3.63 ± 0.30a 14.52 ± 1.35e 14.97 ± 1.38e 104.13 ± 0.58a 25.11 ± 2.00a
Open in a new tab

Data were presented as mean value ± standard deviation.

Significant differences were showed by different small letters (p < 0.05) based on Duncan's multiple range test.

3.3. E-nose analysis

E-nose is used to investigate the effect of post-ripening on the overall odour profile of ‘Cuixiang’ kiwifruit. Radargrams were plotted based on the response data of the sensors to reflect the odour distributions of different samples (Fig. 2A). Sensors S2, S6, S7 and S8 were responsive to ‘Cuixiang’, with the highest response values recorded by S7 (sulphide, terpenoids) and S2 (nitrogen oxides). As post-ripening progressed, the response values of the above four sensors increased gradually in general, indicating that the post-ripening process was accompanied by the enrichment of nitrogen oxides, sulphide and terpenoids. The response values of E-nose sensors S2, S6 and S7 also gradually enhanced in ‘Xuxiang’ kiwifruit during post-ripening (Chai et al., 2022). S2 has strong broad-spectrum sensitivity, whose increase suggested the stronger odour in kiwifruit along post-ripening. Stec, Hodgson, Macrae, and Triggs (1989) also reported that post-ripened fruit had a stronger aroma than freshly picked fruit. Notably, the sensitivity of S8 (alcohol and aromatic compounds) to ‘Cuixiang’ remained low for the first eleven days of post-ripening, but increased abruptly at 13 d, when it had already entered the over-ripening stage. This undesirable odour might originate from anaerobic metabolism promoted by the high respiration and ethylene levels, which further accelerated starch degradation and alcoholic fermentation, ultimately leading to the formation of alcoholic odour (Huan et al., 2021). The substantial increase in the response value of S8 to overripe kiwifruit were also found in ‘Hongshi No.2’ (Wang et al., 2023).

Fig. 2.

Fig. 2

Open in a new tab

E-nose sensor response data (A), LDA discriminant analysis (B) and systematic cluster analysis (C), and E-tongue sensor response data (D), PCA discriminant analysis (E) and systematic cluster analysis (F) of ‘Cuixiang’ kiwifruit at different post-ripening stages.

The LDA results in Fig. 2B showed that LD1 and LD2 together explained 99.10 % of the variance in the samples, indicating the obvious differences in the overall odour profiles of ‘Cuixiang’ at different post-ripening stages. Due to the sudden increase in the response values of S6 and S8, sample D13 differed significantly from others in both LD1 and LD2 direction, and was also classified separately by HCA (Fig. 2C).

3.4. E-tongue analysis

The overall taste variation of ‘Cuixiang’ kiwifruit during post-ripening was examined through E-tongue, an artificial intelligence system to detect taste by simulating human taste perception, and the results were shown in Fig. 2D. ZZ (around 1700–1900), JE (around 1700–1800) and GA (1700–1900) were the most sensitive for all samples, followed by JB (1400–1600), BB (1300–1500) and CA (1200–1400). JE, GA and JB were the most sensitive to sourness (Table S3), and as post-ripening progressed, whose response values decreased in general, indicating that the acidity of ‘Cuixiang’ gradually decreased, consistent with the results of human sensory evaluation. ZZ and BB were the most sensitive to sourness and sweetness, and their response values gradually increased, peaked at 11 d and then decreased. For sweetness, the results indicated that the sweetness of ‘Cuixiang’ gradually increased within 1–11 d of post-ripening and then decreased. For sourness, the changes in ZZ and BB response values were different from JE, GA and JB, but the decrease after 11 d was consistent. Wang et al. (2021a) observed that the acidity of ‘Qinmei’ kiwifruit also increased in the early and decreased significantly in the later stage during post-ripening. In summary, the overall taste of ‘Cuixiang’ changed significantly during post-ripening, manifested by a decrease in acidity and a gradual increase in sweetness, which was consistent with the sugar-acid changes of ‘Hayward’ during post-ripening (Yang et al., 2024). JE, GA and JB, most sensitive to sourness, had the lowest response values at 13 d, while ZZ, BB and CA, most sensitive to sweetness, had the highest response values at 11 d. Combining the results of E-nose and human sensory evaluation, it could be concluded that 11 d was more suitable for consumption than 13 d, being the ‘optimal edible window’ for ‘Cuixiang’ during the post-ripening process.

The PCA results showed that PC1, PC2 and PC3 together explained 99.30 % of the total variance in the samples (Fig. 2E), which suggested that the overall taste profile of ‘Cuixiang’ during post-ripening period varied significantly and could be clearly distinguished by PCA. HCA further revealed that the samples could be classified into four classes when the euclidean distance was greater than 40, among which D13 was a separate class (Fig. 2F), the same as the classification results from E-nose.

3.5. Volatile metabolomic analysis

Samples for volatile metabolomic analysis were selected through the clustering results of E-nose and the aroma attribute in human sensory evaluation, to investigate the changes of VOCs in ‘Cuixiang’ at different post-ripening stages. In Fig. 2C, as the initial stage of post-ripening, 1 d was clustered into the first category. The second category (3 d, 5 d, 7 d) was the rapid softening stage, and there was no significant difference in aroma scores between 3 d and 5 d (Fig. 1A), but a sharp increase on 7 d with superior aroma scores. Thus 7 d was selected among the second category. The third category (9 d, 11 d) was the edible stage, and 11 d was selected because of its significantly highest aroma score through the entire post-ripening stage. Sample of 13 d was in the overripe stage and clustered into a separate category, when ‘Cuixiang’ was over soft and gave off a slight alcohol flavor, which was unsuitable for consumption. Therefore, samples of D1, D7 and D11 were selected for volatile metabolomic analysis.

The total ion current plot and correlation analysis for the three sample groups were shown in Figure S2AB, and the three biological replicates in each group represented good stability and data reproducibility. PCA was further conducted to analyze the credibility of the results and the overall VOCs differences (Fig. 3A). PC1 and PC2 accounted for 94.55 % of the total variance in the samples, and with the extension of post-ripening time, the sample groups were distributed from left to right along PC1 with good separating effects, indicating significant changes in VOCs. The total VOCs content (TVOC) of ‘Cuixiang’ represented no significant difference (p > 0.05) among the three groups (Fig. 3B), concluding that the changes in aroma characteristics of ‘Cuixiang’ at different post-ripening stages were mainly attributed to the variation in types and concentrations of specific VOCs.

Fig. 3.

Fig. 3

Open in a new tab

Volatile organic compounds (VOCs) in ‘Cuixiang’ kiwifruit at different post-ripening stages. Plots of PCA scores (A). Total VOCs content (B). VOCs species composition and number percentage (C). Thermograms of different types of VOCs content (D). In (B), error bars represented the standard deviation of the three biological replicates, and different small letters represented significant differences (p < 0.05) based on Duncan's multiple range test. In (D), significant differences were showed by whether * was marked (p < 0.05) based on Duncan's multiple range test.

A total of 513 VOCs were identified in ‘Cuixiang’ kiwifruit (Table S4), including 104 terpenoids, 88 esters (E), 79 heterocyclic compounds (Hc), 49 ketones, 47 alcohols (Alc), 44 hydrocarbons, 38 aldehydes, 25 aromatics, 13 acids, 9 amines, 8 nitrogen/sulfur compounds, 5 phenols, 3 others and 1 halogenated hydrocarbon. Terpenoids, esters, and heterocyclic compounds were the most diverse VOCs in ‘Cuixiang’, accounting for 20.27 %, 17.15 %, and 15.40 % of the total number of all VOCs respectively (Fig. 3C). They were also the most abundant substances in all samples, among which esters had the highest content, accounting for 17.18–17.76 % of TVOC, followed by terpenoids (16.27–17.48 %), heterocyclic compounds (16.26–17.35 %), ketones (11.10–13.26 %) and alcohol (12.62–12.86 %), while the contents of the remaining types of VOCs in TVOC were less than 10 %. Terpenoids could provide spice, herbaceous, and citrus flavors to food (Lan et al., 2023), and their concentration continued to decrease during storage (Fig. 3D), suggesting that the loss of herbaceous aroma occurred throughout the post-ripening process of ‘Cuixiang’ kiwifruit. Similarly, aldehydes with herbaceous aroma also decreased during the post-ripening period. Esters and alcohols imparted rich floral and fruity aromas to food, constituting key volatile components of kiwifruit (Fang, Qi, Li, Chen, & Gong, 2024; Huan et al., 2020; Xiao et al., 2024). Their concentrations gradually decreased during the post-ripening process, though the differences were not significant, suggesting that subsequent analyses should focus on the influence of the differential monomer compounds on the aroma change of ‘Cuixiang’. Moreover, the rise in aromatics content during the late post-ripening stage further accounted for the increased response value of the E-nose S8 sensor at this period (Fig. 2A). The consistency between E-nose and volatile metabolomic analysis has been widely verified (Huang, Peng, et al., 2025; Xiao et al., 2024), which collectively supported the scientific rationality of selecting samples for volatile metabolomic analysis based on E-nose results combined with human sensory evaluation as conducted earlier.

3.6. Identification of DVMs

OPLS-DA was used to pairwise discriminate the samples of D1, D7 and D11 at different post-ripening stages. The predictive parameters R2Y and Q2 of the three OPLS-DA models were all greater than 0.9 and 0.5, respectively (Fig. S2C-E), indicating that the models were valid and well fitted to the data. The OPLS-DA score plot showed that ‘Cuixiang’ had clear separation trends among the three comparison groups, suggesting that the volatile metabolic profiles of kiwifruit would change along the post-ripening process.

A total of 28 VOCs were identified as DVMs in ‘Cuixiang’ kiwifruit at different post-ripening stages (Fig. 4A, Table S5). Compared with D1, three DVMs were up-regulated and nine were down-regulated in D7 (Fig. 4B), and the three up-regulated DVMs were all aromatics; 10 DVMs were up-regulated and 11 DVMs were down-regulated in D11, and the up-regulated DVMs were mainly esters and aromatics (Fig. 4C). Compared to D7, 8 DVMs were up-regulated and 4 DVMs were down-regulated in D11, and again esters predominated in up-regulated DVMs (Fig. 4D). In summary, throughout the post-ripening from D1 to D11, the mainly up-regulated substances were esters and aromatics, with aromatics predominating in the early post-ripening period and esters in the later. The three aromatics up-regulated in the early period were o-xylene, m-xylene and styrene (Table S5), which presented geranium, plastic and spice aroma, respectively, and their increased contents gave kiwifruit a more complex and attractive aroma. Esters were the most abundant VOCs in kiwifruit, being the main source of its fruity, floral and sweet aroma (Lan et al., 2023), and the increase of their contents were also observed in ‘Bruno’ and ‘Hayward’ kiwifruit during post-ripening (Garcia, Quek, Stevenson, & Winz, 2012; Huan et al., 2020). Fig. 4D showed that 7 of the 12 VOCs that had significant differences between D7 and D11 were esters, among which 5 were up-regulated. These esters were described as fruity, floral and sweet (Fig. 5) (Lan et al., 2023), whose changes had significant effects on fruit's aroma. There were only 2 shared DVMs among the three comparison groups (Fig. 4A, Fig. 5), both of which were esters, namely E-butanoic acid-3-hexenyl ester and Z-butanoic acid-3-hexenyl ester, whose contents constantly decreased during post-ripening. These DVMs might be important factors in altering the aroma characteristics of ‘Cuixiang’ at different post-ripening stages and were further investigated.

Fig. 4.

Fig. 4

Open in a new tab

Number of differential volatile metabolites (DVMs) exhibited through venn diagrams (A) and histograms (B—D). Flavor wheels (E) and sankey diagram (F) of key DVMs between 1 d and 11 d samples.

Fig. 5.

Fig. 5

Open in a new tab

Key DVMs based on volatile metabolomic results.

3.7. Analysis of flavor characteristics of DVMs

Aroma is an important component of fruit flavor, and was also the core factor determining consumers' purchase intention (Garcia et al., 2012). The key DVMs and their annotated sensory flavor profiles in comparison of D1 vs. D11 were presented using the flavor wheel and sankey diagram (Fig. 4E-F). During the eleven days of post-ripening process, 5, 3 and 3 DVMs were annotated as fruity, green and sweet, respectively (Fig. 4E), and as the most frequently annotated odours, they were crucial for the changes of aroma during the post-ripening of ‘Cuixiang’. As shown in Fig. 4F and Table S5, during post-ripening, the contents of 3 of the 5 DVMs with fruity aroma were significantly increased, namely methyl hexanoate (E50), methyl methacrylate (E30) and 3(2H)-furanone-4-methoxy-2,5-dimethyl (Hc20), whose total content increased from 0.01 to 0.29 μg g−1. The contents of the other 2 fruity DVMs declined significantly, namely Z-butanoic acid-3-hexenyl ester (E27) and heptyl acetate (E15), with total contents decreasing from 1.03 to 0.41 μg g−1. Overall, the fruity aroma of ‘Cuixiang’ was mainly up-regulated during the post-ripening. Z-butanoic acid-3-hexenyl ester (E27) and heptyl acetate (E15) were also labeled with a greenness odour. Although the content of 3-penten-2-ol (Alc12), which shared the annotation of greenness odour, increased significantly from 0.00 to 0.53 μg g−1, the decrease of the former two led to the reduction in greenness odour of ‘Cuixiang’ during post-ripening. For sweet aroma, only heptyl acetate (E15) decreased from 0.92 to 0.41 μg g−1, and the remaining 2 DVMs including 3(2H)-furanone-4-methoxy-2,5-dimethyl (Hc20) and benzyl benzoate (E20) significantly increased from 0.01 to 0.09 μg g−1, indicating the up-regulation of sweetness. Apart form sweet aroma, heptyl acetate (E15) also showed a grassy odour, which further indicated that the greenness odour of ‘Cuixiang’ gradually weakened while the fruity and sweet aroma gradually intensified during post-ripening.

In order to further investigate the aroma changes of ‘Cuixiang’ at specific post-ripening stage, the detailed changes in the aroma profile of kiwifruit during 1–7 d and 7–11 d were explored (Fig. 5). There were only 2 DVMs shared by D1 vs. D7 and D7 vs. D11, namely E-butanoic acid-3-hexenyl ester and Z-butanoic acid-3-hexenyl ester, which were isomers, and whose contents reduced during the post-ripening. Z-butanoic acid-3-hexenyl ester had a pronounced fresh and greenness odour, suggesting that the loss of grassy odour ran through the whole post-ripening process of ‘Cuixiang’ kiwifruit. Z-butanoic acid-3-hexenyl ester was confirmed to specifically induce stomatal closure in plants, thereby assisting in reducing water loss, defending against pathogen invasion, and further enhancing the plant's overall resistance and tolerance to various stress conditions (Payá et al., 2024). Therefore, beyond contributing characteristic aroma, it might also exert physiological functions critical for maintaining fruit quality during the post-ripening period of ‘Cuixiang’, such as inhibiting rot diseases and delaying water loss. For the unique 10 DVMs between D1 and D7, 4 associated with green and melon aroma showed reducing trends, namely isobutyl isovalerate, 2,6-dimethyl-5-heptenal, E-3-hexenyl acetate and 2-nonanol. In addition, although the content of isobutyl 2-methylbutyrate with sweet and fruity aroma declined during post-ripening, its lower content (0.57–0.27 μg g−1) did not affect the overall aroma profile of kiwifruit (Table S5). Therefore, the aroma character of ‘Cuixiang’ kiwifruit during 1–7 d of post-ripening was mainly manifested as the reduction in greenness odour.

In the comparison of D7 vs. D11, 6 of the 10 unique DVMs with aroma descriptors were up-regulated, which were all related to positive descriptors of fruity, sweet and floral. Thus, during the 7–11 d post-ripening period, the aroma characteristics of ‘Cuixiang’ were mainly manifested as a gradual enrichment of these pleasant aromas. These 6 DVMs included benzyl benzoate, 3(2H)-furanone-4-methoxy-2,5-dimethyl, methyl methacrylate, methyl benzoate, methyl hexanoate and methyl caprate, which were all esters except 3(2H)-furanone-4-methoxy-2,5-dimethyl as a heterocyclic compound. Notably, methyl caprate also exhibited an alcoholic odour, indicating a tendency towards an alcohol odour, although ‘Cuixiang’ still presented good aroma profile at 11 d of post-ripening. In addition, the content of 4,5-dihydro-3-furoic acid gradually decreased during 7–11 d, suggesting that post-ripening promoted the degradation of acids.

3.8. Non-volatile metabolomic analysis and identification of DAMs

Non-volatile metabolomic analysis of D1, D7 and D11 were performed. According to the total ion flow diagram and intra group correlation analysis (Figure S3AB), the three biological replicates of each group had good reproducibility and reliability. PCA results showed clear distinctions among the three groups (Fig. S3C), especially on the PC2 direction, suggesting that the non-volatile metabolites in the ‘Cuixiang’ kiwifruit varied significantly during the post-ripening. A total of 1528 non-volatile metabolites were detected in all samples, including 12 classes, namely 444 amino acids and their derivatives, 153 phenolic acids, 60 nucleotides and their derivatives, 168 flavonoids, 11 quinones, 70 lignans and coumarins, 11 tannins, 97 alkaloids, 100 terpenoids, 87 organic acids, 180 lipids, and 147 other substances (Fig. S3D).

OPLS-DA was valid and fitted well to the data (Q2 > 0.8) of non-volatile metabolomic (Fig. S4A). Clear separation trends were shown among the three groups, suggesting that the metabolic profile of ‘Cuixiang’ changed significantly as post-ripening process. Overall, a total of 238 DAMs were identified (Fig. S4B and Table S6). 88 DAMs were identified between D1 and D7, with 65 up-regulated and 23 down-regulated (Fig. S4D). 158 DAMs were identified between D1 and D11, with 67 up-regulated and 91 down-regulated (Fig. S4E). And 107 DAMs were identified between D7 and D11, with 27 up-regulated and 80 down-regulated (Fig. S4C). These altered DAMs might have important effects on the nutritional and functional properties of ‘Cuixiang’ kiwifruit at different post-ripening stages and were further analyzed.

3.9. Analysis of DAMs

3.9.1. DAMs of sugars and organic acids

Kiwifruit accumulate carbohydrates in the form of starch before harvest, and during post-ripening, amylases hydrolyze starch to form soluble sugars that sweeten the fruit (Stec et al., 1989). A total of 15 saccharides were identified as DAMs, of which 7 were continuously up-regulated (Fig. 6A), namely D-sucrose, sucrose-6-phosphate, trehalose-6-phosphate, d-glucose-1,6-bisphosphate, laminaran, galactinol and D-panose. These up-regulated saccharides might accounted for the significant increases in TSS and sweetness of ‘Cuixiang’ during post-ripening. The accumulation of soluble sugars in kiwifruit mainly involved the starch-sugar metabolism pathway, and soluble sugars such as D-sucrose, d-fructose and d-glucose, were the main determinants of kiwifruit sweetness (Nardozza et al., 2020). However, d-fructose and d-glucose were absent from DAMs in this study, possibly because they synthesized sucrose under the catalysis of sucrose phosphate synthase (Smeekens & Hellmann, 2014). Notably, trehalose-6-phosphate could regulate fruit growth and metabolism by inhibiting the catalytic activity of sucrose non-glycolytic related kinase 1. Meitzel et al. (2021) showed that D-sucrose content increased when trehalose-6-phosphate increased, which was consistent with our results. Galactinol was a direct product of galactinol synthase, a key enzyme in raffinose family oligosaccharides (RFOs) biosynthesis in higher plants, and when plants were faced with stress, the increased biosynthesis of soluble sugars in the cells, such as RFOs, could enhance their tolerance capacity (Salvi, Kamble, & Majee, 2018). So that during the post-ripening aging period of kiwifruit, galactinol content could continuously increase.

Fig. 6.

Fig. 6

Open in a new tab

Differential accumulation metabolites (DAMs) based on non-volatile metabolomic: sugars (A), acids (B), amino acids and their derivatives (C).

Organic acids are one of the main components determining fruit flavor and play an important role in maintaining fruit quality. And during the post-ripening of kiwifruit, part of organic acids are consumed through respiration, so the content of titratable acids constantly decrease (Famiani, Battistelli, Moscatello, Cruz-Castillo, & Walker, 2015). Most of the organic acids (9 out of 14) in DAMs were significantly down-regulated during the post-ripening of ‘Cuixiang’ (Fig. 6B), namely abscisic acid, jasmonic acid, 9-oxononanoic acid, argininosuccinic acid, methanesulfonic acid, 1-aminocyclopropane-1-carboxylic acid, 3-ureidopropionic acid, iminodiacetic acid and 2,2-dimethylsuccinic acid. Their changes were consistent with the increase in pH and decrease in TA observed in the previous study (Li et al., 2024), possibly being the main reason for the gradual decrease of fruit acidity during the post-ripening of ‘Cuixiang’. Abscisic acid, as a endogenous hormone, could promote the expression of genes associated with ripening, such as carbohydrates, pigments and cell wall components metabolism, and ultimately lead to fruit ripening and softening (Leng, Yuan, & Guo, 2013). Li et al. (2014) detected a sharp decline in endogenous abscisic acid content during fruit senescence in ‘Bayuecui’ peaches, and the results of this study further confirmed the conclusion. Jasmonic acid was a lipid hormone synthesized endogenously by plants, as a signal molecule or inducer, playing a key role in delaying flowering, affecting leaf senescence, yellowing and fruit ripening (Zhang et al., 2023). The study of Yang, Deng, et al., 2024 showed that a decrease in jasmonic acid level was an intrinsic manifestation of tomato ripening, and the present study reached a consistent conclusion. During the tricarboxylic acid cycle, succinic acid was catalyzed by succinate dehydrogenase to produce fumaric acid, and the contents of succinic acid decreased continuously, as did its isomer 2,2-dimethylsuccinic acid throughout the post-ripening of ‘Cuixiang’.

3.9.2. DAMs of amino acids

Amino acids and their derivatives were abundant in ‘Cuixiang’ kiwifruit, with as high as 444 types detected by non-volatile metabolomic, and they also predominated in DAMs, totaling 59. K-means clustering classified the 59 amino acids DAMs into up-regulated and down-regulated categories, among which the down-regulation category accounted for the majority, totaling 47 (Fig. 6C). This might be due to the fact that most amino acids could serve as precursors for flavor substances or secondary metabolites such as polyphenols, undergoing degradation and transformation during the post-ripening process of kiwifruit (Heleno, Martins, Queiroz, & Ferreira, 2015; Xiao et al., 2024). The 47 down-regulated amino acids included 2 essential amino acids (DL-methionin, l-lysine), 3 non-essential amino acids (L-aspartic acid, L-glutamic acid, L-asparagine), and 41 amino acids derivatives. It has been proven that the levels of serine acetyltransferase and cysteine synthetase involved in the synthesis of DL-methionine, as well as phosphoglycerol dehydrogenase involved in the synthesis of Ala-Gly, gradually decreased during post-ripening of ‘Hayward’ kiwifruit (Tian et al., 2021). Therefore the decrease in the activity of the relevant amino acid synthetases might be responsible for the decrease of the above amino acids and derivatives during post-ripening of ‘Cuixiang’. It was noted in section 3.2 that the S7 sensor of E-nose, sensitive to sulphide and terpenoids, had a significant increased response during post-ripening, which might be due to the sulphides produced by sulfur-containing amino acids degradation, such as γ-glutaminemethionine and L-homomethionine (Wang et al., 2023). The significant down-regulation of the two in this study also confirmed this (Table S6).

Except Glu-Pro-Leu in sub class 2, there were 11 consistently up-regulated amino acids during post-ripening, including Phe-Tyr-Thr, Jasmonoyl-L-Isoleucine, Gly-Val-Val, Met-Glu-Arg, L-aspartic acid-O-diglucoside, Phe-Gln, arginyl-valine, Phe-Glu-His, Phe-Phe-Glu, Arg-Ser-Trp and Ser-Asp-Asn (Fig. 6C). Mao et al. (2023) also observed that the levels of multiple amino acids were up-regulated throughout the post-ripening process of ‘Jinyan’ kiwifruit. During post-ripening, respiration gradually strengthened and energy metabolism became active. The glycolysis pathway, tricarboxylic acid cycle and pentose phosphate pathway satisfied the energy demand of fruit on the one hand, and on the other hand, they could provide intermediates for various metabolic processes, such as the derivatization of organic acids and amino acids. Previous studies showed that amino acid synthases such as aspartate aminotransferase ASP3 was strongly up-regulated during the post-ripening of kiwifruit, playing an important role in the transformation and accumulation of amino acids (Mao et al., 2023; Tian et al., 2021). The up-regulated Phe-Gln, as an essential amino acid, played a positive role in neurotransmitters synthesis, antioxidant and cardiovascular health improvement, and was also found to be significantly elevated during the post-ripening of ‘Hayward’ (Tian et al., 2021). Overall, the up-regulation of amino acids such as Phe-Gln during post-ripening significantly improve the nutritional value of ‘Cuixiang’, whereas the down-regulation of Ala-Gly, DL-methionine and γ-glutaminemethionine, etc. might produce a large number of flavor compounds, polyphenols and other functional substances, improving the flavor and functional characteristics.

3.9.3. DAMs of lipids

Among all kiwifruit samples, a total of 180 lipids were detected, of which 38 were identified as DAMs, accounting for 21.11 % of the total DAMs (Table S6). The lipids in DAMs were classified into lyso phosphatidylethanolamine (LPE), lyso phosphatidylcholine (LPC), glycerol ester (LG) and free fatty acids (LF) (Fig. 7A). When fruit received senescence signals, phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and other phospholipid molecules were hydrolyzed and acted as signals to initiate subsequent metabolic pathways to complete the plant senescence process (Su et al., 2024). Thus, as degradation products of PC and PE, most (13/18) LPEs and LPCs were up-regulated during post-ripening, except for 1–3-propan-2-yl-(E)-hexadec-9-enoate, LysoPC 16:1, LysoPC 16:1 (2n isomer), LysoPC 15:1 and LysoPC 10:0, which were down-regulated. And the down-regulation of these five substances were same as the trend of LPE and LPC during ripening of banana (Sun et al., 2020). LGs were important energy storage compounds in biological organisms and were crucial for energy metabolism. Mainly composed of polyunsaturated fatty acids, LGs in plants were easily to be oxidized and degraded, and could provide energy for the fruit post-ripening process (Huang et al., 2022). Most of the LGs (6/10) were down-regulated during post-ripening, including PI (18:2/0:0), 1-oleoyl-sn-glycerol, gingerglycolipid a, 1-palmitoyl-sn-glycerol-3-O-diglucoside, LysoPG 16:0 and 2-linoleoylglycerol-1,3-di-O-glucoside, consistent with the changes of LG contents during ripening of pink plantain (Sun et al., 2020). For LFs, undecanedioic acid, 9,10,13-trihydroxy-11-octadecenoic acid, 9-hydroxy-13-oxo-10-octadecenoic acid, 9-hydroxy-12-oxo-10(E),15(Z)-octadecadienoic acid and 10-nitro-9(E)-octadecenoic acid, the 5 metabolites were down-regulated during the post-ripening of ‘Cuixiang’, which was consistent with the changes of LFs during the ripening of pink banana reported by Su et al. (2024). In order to protect themselves, plants converted LGs and LFs into neutral tria-cylglycerol to mitigate damage caused by senescence (Su et al., 2024), which might be the reason for the down-regulation of LGs and LFs levels throughout the post-ripening of ‘Cuixiang’. Moreover, hydroperoxide lyase and lipoxygenase could catalyze the conversion of LFs to aldehydes, which were subsequently reduced by alcohol dehydrogenase to produce alcohols, and then the alcohols were further converted by alcohol acyl-coenzyme A transferase to form esters. Thus the oxidation and decomposition of LFs were also crucial for the formation of aromas in fruits (Xiao et al., 2022; Xiao et al., 2024). In summary, although post-ripening caused the loss and decomposition of a large amount of lipids, this process ultimately led to the degradation of the cell wall, which in turn played a positive effect on the softening and edible of ‘Cuixiang’ kiwifruit, and could enhance its characteristic flavor.

Fig. 7.

Fig. 7

Open in a new tab

DAMs based on non-volatile metabolomic: lipids (A), phenols (B), terpenoids (C).

3.9.4. DAMs of polyphenols

Polyphenols are secondary metabolites involved in the metabolism of phenylpropane/phenylalanine, which not only had certain effects on color and flavor of plants, but also had the functions of anti-oxidation, anti-cancer and anti-stress (Han, Cai, Yu, Yu, & Wu, 2023; Su et al., 2024). The main polyphenols DAMs during post-ripening of ‘Cuixiang’ kiwifruit had three major groups: phenolic acids, flavonoids, lignans and coumarins (Fig. 7B).

Phenolic acids, including benzoic acid derivatives and cinnamic acid derivatives, are sources of antioxidant actives in plants, whose composition and content play an important role in resistance to abiotic stresses (Heleno et al., 2015). 19 phenolic acids were identified as DAMs, which could be divided into 3 sub classes according to the trend of their levels (Fig. 7B). Subclass 1 consisting 8 monomers had a down-regulated tendency, while subclass 2 and 3 generally showed up-regulated tendencies during post-ripening. 6 monomers in subclass 2 were up-regulated from 1 to 7 d but subsequently down-regulated, resulting in levels at 11 d roughly equivalent to those at 1 d. This trend of first increasing and then decreasing was consistent with the changes of polyphenols in ‘Hayward’ during post-ripening (Niu et al., 2023). Suclass 3 including 1-(4-methoxyphenyl)-1-propanol, 4-caffeoylshikimic acid, 5-O-caffeoylshikimic acid, cinnamic acid, 3-O-caffeoylshikimic acid and anthranilate-1-O-sophoroside, was consistently up-regulated. The reason probably was that cinnamic acid-4-hydroxylate, the second key enzyme in the phenylpropane pathway, could catalyze the synthesis of phenolic acids, and its activity was basically increased during post-harvest of kiwifruit (Niu et al., 2023). Remarkably, in the phenylalanine pathway, phenylalanine was firstly converted to cinnamic acid by phenylalanine ammonia-lyase, and therefore cinnamic acid was continuously up-regulated during post-ripening (Han et al., 2023), which was consistent with the results obtained in this study.

Flavonoids widely exist in fruit, vegetable and tea, which are important natural antioxidants with a variety of potential health-promoting effects on human body (Wang, Vanga, & Raghavan, 2019). Only 12 flavonoids were identified as DAMs, including 2 flavones, 4 chalcones, 1 flavanone, 2 flavonols and 3 other flavonoids. Most of the substances (8/12) were up-regulated during post-ripening (Fig. 7B). Among the 8 up-regulated DAMs, 5-hydroxy-2-methoxyxanthen-9-one, 3,4,2′,4′,6′-pentahydroxychalcone-4’-O-glucoside, 1,3,6,7-tetrahydroxy-2-(3,4,5-trihydroxyoxan-2-yl)xanthen-9-one, eriodictyol-8-C-glucoside and 6,7,3′,4′-tetrahydroxyflavone peaked at 11 d. Another 3 up-regulated DAMs decreased after peaking at 7 d, and this trend was consistent with the change of flavonoids in ‘Hayward’ kiwifruit during storage (Wang, Li, Yang, Wu, & Shen, 2022). Senescence stress induced the production of H2O2, and consumption to alleviate oxidative damage might be the reason for the decline of these flavonoid metabolites in the later stages of storage (Sharma et al., 2019).

Lignans are a class of natural polyphenols polymerized from phenylpropyl derivatives (C6-C3 monomer), and coumarins are a kind of biologically active substances with positive effects such as antimicrobial, anticancer, antiviral and antioxidant (Pereira, Franco, Vitorio, & Kummerle, 2018). 4 lignans and 2 coumarins were identified as DAMs (Fig. 7B). Only secoisolariciresinol-9’-O-xyloside was consistently up-regulated during post-ripening, while the other three lignans showed a downward trend. For coumarins, ayapin and isoscopoletin-glucoside firstly increased and then decreased during post-ripening, consistent with the change of coumarin content in peaches during storage observed by Han et al. (2023).

In conclusion, most polyphenols showed an up-regulated trend during post-ripening of ‘Cuixiang’, which on the one hand enhanced its functional properties and contributed to human health, on the other hand, as antioxidants, they helped to scavenge free radicals during fruit senescence, and played an important role in alleviating the oxidative damage of cells.

3.9.5. DAMs of terpenoids

Terpenoids, simple hydrocarbons with multiple isoprene units, were the largest and most diverse class of secondary metabolites produced by plants. Terpenoids were of great significance in human health such as anti-oxidation, enhancing immunity, lowering cholesterol, treating obesity-related diseases and could also protect plants from abiotic stress (Lin et al., 2023). A total of 39 terpenoids were identified as DAMs during the post-ripening of ‘Cuixiang’ kiwifruit (Fig. 7C), including 35 triterpenes, 4 sesquiterpenes, and 1 diterpene, which were classified into two major groups by K-means. Most terpenoids exhibited an initial rise and subsequent fall. This trend might be attributed to the active physiological activity and strong stress resistance at early stage of post-ripening of kiwifruit, supporting higher terpenoids synthesis (Thimmappa, Geisler, Louveau, O'Maille, & Osbourn, 2014). In the later stage of post-ripening, however, sever cellular aging and structural collapse reduced stress defense capacity, thereby weakening terpenoids metabolism (Tholl, 2015).

3.10. Combined analysis of volatile and non-volatile metabolomic

Green leaf volatiles and their derivatives (GLVs) were the main type of DVMs identified during the post-ripening process of ‘Cuixiang’, including 2,6-dimethyl-5-heptenal, E-3-hexenyl acetate, 2-nonanol and E/Z-butanoic acid-3-hexenyl ester, etc. (Fig. 5). They originated from C18 unsaturated fatty acids linoleic acid and linolenic acid, and generated through the lipoxygenase (LOX) pathway (Dudareva, Klempien, Muhlemann, & Kaplan, 2013). LFs and jasmonic acid both participated in the LOX pathway, with the former acting as byproducts and the latter competing with GLVs for the core substrate. The activity balance of hydrogen peroxide lyase and crotonyl-CoA synthetase in the LOX pathway determined whether the metabolic flow favored GLVs or jasmonic acid synthesis. And jasmonoyl-L-isoleucine was the form of jasmonic acid with the strongest biological activity (Zhang, Jackson, Li, & Zhang, 2025). At the functional level, as previously mentioned, Z-butanoic acid-3-hexenyl ester could induce stomatal closure in plants, and abscisic acid also possessed this regulatory capacity. However, their mechanisms of action differed, and they did not exhibit synergistic effects (Payá et al., 2024). Furthermore, the jasmonic acid and abscisic acid signaling pathways could regulate the expression levels of key enzymes involved in terpenoids synthesis through transcription factors, thereby indirectly controlling the biosynthesis of volatile terpenoids (Jiang et al., 2024).

During the post-ripening process of ‘Cuixiang’ kiwifruit, in addition to jasmonoyl-L-isoleucine, the aforementioned GLVs, LFs, jasmonic acid, abscisic acid and volatile terpenoids all exhibited significant downward trends (Fig. 3D, Fig. 5, Fig. 6B, C, 7A). From the perspective of physiological functional interrelationships, these substances all played crucial roles in the plant immune defense system, helping plants resist insect feeding, pathogen infection, mechanical damage, and environmental stress, and jointly constituted the defense function network during the post-ripening period of kiwifruit. The widespread decrease of the above substances indicated that the ‘Cuixiang’ kiwifruit weakened the intensity of immune defense during the post-ripening process, directing the limited carbon sources and energy towards the formation of edible quality. This was evidenced by the increase in aromatic and sweet-scented esters, along with the accumulation of soluble sugars like sucrose (Fig. 4F, 6A). Concurrently, jasmonoyl-L-isoleucine helped the fruit maintain its capacity to respond to potential stress risks.

In conclusion, the LOX pathway played a central regulatory role in the post-ripening process of ‘Cuixiang’, and its two branch products, GLVs and jasmonic acid, were closely related to the formation of fruit post-ripening quality. For upcoming research and industrial application focused on post-harvest preservation and post-ripening quality regulation of kiwifruit, the dynamic changes and regulatory mechanisms of the LOX pathway deserve special attention. Furthermore, achieving metabolic equilibrium between the fruit defense system and edible quality formation represented a novel regulatory approach for extending kiwifruit's post-harvest storage period while simultaneously improving its post-ripening quality. This provided fresh research perspectives and practical directions for resolving the long-standing core contradiction of the kiwifruit industry: longer preservation period accompanied by deteriorated quality.

4. Conclusion

The changing laws of sensory quality, volatile and non-volatile metabolites of ‘Cuixiang’ kiwifruit during post-ripening were analyzed. Overall, except for the appearance score continued to decrease during post-ripening, other sensory attributes, including color, aroma, taste and texture all peaked at 11 d, which was the optimal ‘consumption window’ for ‘Cuixiang’ kiwifruit. Results of volatile metabolomic indicated that the loss of greenness odour ran through the whole post-ripening process of ‘Cuixiang’, especially during the first 7 d, due to the down-regulated contents of isobutyl isovalerate, 2,6-dimethyl-5-heptenal, E-3-hexenyl acetate and 2-nonanol. From the 7–11 d of post-ripening, the contents of benzyl benzoate, 3(2H)-furanone-4-methoxy-2,5-dimethyl, methyl methacrylate, methyl benzoate, methyl hexanoate and methyl caprate increased significantly, mainly manifesting a gradual enrichment of fruity, sweet and floral aromas. In addition, at 11 d of post-ripening, ‘Cuixiang’ had a tendency to produce an alcoholic odour, although it still exhibited a pleasant aroma profile. During the post-ripening of ‘Cuixiang’, 7 sugars, represented by D-sucrose, sucrose-6-phosphate and trehalose-6-phosphate, were continuously up-regulated, while 9 organic acids, represented by abscisic acid, jasmonic acid and argininoamber acid, continued to be down-regulated, which was the main reason for the gradual increase of fruit sweetness and decrease of acidity. The up-regulation of amino acids such as Phe-Gln during post-ripening significantly improved the nutritional value of kiwifruit, whereas the down-regulation of Ala-Gly, DL-methionine and L-cystine, etc. might produce a large number of flavor compounds, polyphenols and other functional substances, improving the flavor and functional characteristics of fruit. For lipids, although post-ripening of kiwifruit caused the loss and decomposition of most of them, this process ultimately led to the cell wall degradation, which in turn played a positive effect on the softening and edible of the fruit. Most phenolic acids, flavonoids and other polyphenols showed an up-regulation trend during post-ripening. On the one hand, they enhanced the functional properties of the fruit and contributed to human health; on the other hand, as antioxidants, they helped eliminate free radicals in the fruit during senescence, and played an important role in alleviating cellular oxidative damage. In summary, the post-ripening process improved the sensory quality of ‘Cuixiang’, and caused significant changes in its metabolites. The jointly analysis of volatile and non-volatile metabolomic indicated the important regulatory function of the LOX pathway and its branch products GLVs and jasmonic acid in the post-ripening process of ‘Cuixiang’, which should be given special attention in the future study. The results could provide theoretical basis for the post-ripening research and storage preservation of ‘Cuixiang’ kiwifruit, and also guide consumers to scientifically determine the optimal stage of its consumption. Moreover, this study offered new insights for addressing a key industry challenge-extending kiwifruit storage without compromising quality-by achieving a metabolic balance between defense responses and edible quality formation.

CRediT authorship contribution statement

Shihan Bao: Writing – review & editing, Visualization, Investigation, Formal analysis, Data curation. Xinyi Li: Writing – original draft, Methodology, Investigation, Data curation. Guoqiang Zhang: Writing – review & editing, Investigation, Formal analysis. Runting Han: Writing – original draft, Investigation, Formal analysis. Yongwu Li: Visualization, Formal analysis, Conceptualization. Xiangyu Sun: Writing – review & editing, Supervision, Methodology. Tingting Ma: Writing – review & editing, Methodology, Funding acquisition, Conceptualization.

Funding sources

This study was supported by the National Natural Science Foundation Project (32372261).

Declaration of competing interest

The authors of the study “Integrated intelligent sensory and metabolomics elucidate the changes in sensory quality and metabolic profile during post-ripening of ‘Cuixiang’ kiwifruit” Shihan Bao, Xinyi Li, Guoqiang Zhang, Runting Han, Yongwu Li, Xiangyu Sun and Tingting Ma declare that they have no financial or personal relationships that may be perceived as influencing the work.

Footnotes

Appendix A

Supplementary data to this article can be found online at https://doi.org/10.1016/j.fochx.2026.103497.

Appendix A. Supplementary data

Supplementary material

mmc1.docx (1.7MB, docx)

Data availability

All data used for the research were described in the article or supplementary materials.

References

  1. Bao S., Li X., Lan T., Wang J., Hu Y., Sun X., Ma T. Effects of different cooking treatments on the sensory qualities and pigmented phytochemicals of carrots. Food Chemistry. 2023;405 doi: 10.1016/j.foodchem.2022.135015. [DOI] [PubMed] [Google Scholar]
  2. Chai J., Liao B., Li R., Liu Z. Changes in taste and volatile compounds and ethylene production determined the eating window of ‘Xuxiang’ and ‘Cuixiang’ kiwifruit cultivars. Postharvest Biology and Technology. 2022;194 doi: 10.1016/j.postharvbio.2022.112093. [DOI] [Google Scholar]
  3. Chen W., Gong L., Guo Z., Wang W., Zhang H., Liu X., Yu S., Xiong L., Luo J. A novel integrated method for large-scale detection, identification, and quantification of widely targeted metabolites: Application in the study of rice metabolomics. Molecular Plant. 2013;6(6):1769–1780. doi: 10.1093/mp/sst080. [DOI] [PubMed] [Google Scholar]
  4. Dadwal V., Aroor M.S., Joshi R., Gupta M. Recent progress in metabolomics research: Insights into fruit metabolome, harvesting techniques and health-promoting bioactives. International Journal of Food Science & Technology. 2024;59(8):5285–5302. doi: 10.1111/ijfs.17308. [DOI] [Google Scholar]
  5. Dudareva N., Klempien A., Muhlemann J.K., Kaplan I. Biosynthesis, function and metabolic engineering of plant volatile organic compounds. The New Phytologist. 2013;198(1):16–32. doi: 10.1111/nph.12145. [DOI] [PubMed] [Google Scholar]
  6. Famiani F., Battistelli A., Moscatello S., Cruz-Castillo J.G., Walker R.P. The organic acids that are accumulated in the flesh of fruits: Occurrence, metabolism and factors affecting their contents-a review. Revista Chapingo. Serie Horticultura. 2015;21(2):97–128. doi: 10.5154/r.rchsh.2015.01.004. [DOI] [Google Scholar]
  7. Fang L., Qi N., Li Y., Chen T., Gong X. Changes in the physicochemical and volatile profiles during the winemaking of marselan in the eastern foot of helan mountain, China. Food Innovation and Advances. 2024;3(4):396–404. doi: 10.48130/fia-0024-0039. [DOI] [Google Scholar]
  8. Garcia C.V., Quek S.-Y., Stevenson R.J., Winz R.A. Kiwifruit flavour: A review. Trends in Food Science & Technology. 2012;24(2):82–91. doi: 10.1016/j.tifs.2011.08.012. [DOI] [Google Scholar]
  9. Han S., Cai H., Yu H., Yu Z., Wu Y. Targeted metabolomic and transcriptomic reveal the regulation of UV–C on phenolics biosynthesis of peach fruit during storage. LWT. 2023;190 doi: 10.1016/j.lwt.2023.115573. [DOI] [Google Scholar]
  10. Heleno S.A., Martins A., Queiroz M.J.R.P., Ferreira I.C.F.R. Bioactivity of phenolic acids: Metabolites versus parent compounds: A review. Food Chemistry. 2015;173:501–513. doi: 10.1016/j.foodchem.2014.10.057. [DOI] [PubMed] [Google Scholar]
  11. Huan C., Du X., Wang L., Kebbeh M., Li H., Yang X., Shen S., Zheng X. Transcriptome analysis reveals the metabolisms of starch degradation and ethanol fermentation involved in alcoholic off-flavour development in kiwifruit during ambient storage. Postharvest Biology and Technology. 2021;180 doi: 10.1016/j.postharvbio.2021.111621. [DOI] [Google Scholar]
  12. Huan C., Zhang J., Jia Y., Li S., Jiang T., Shen S., Zheng X. Effect of 1-methylcyclopropene treatment on quality, volatile production and ethanol metabolism in kiwifruit during storage at room temperature. Scientia Horticulturae. 2020;265 doi: 10.1016/j.scienta.2020.109266. [DOI] [Google Scholar]
  13. Huang C., Li Y., Wang K., Xi J., Xu Y., Si X., Pei D., Lyu S., Xia G., Wang J., Li P., Ye H., Xing Y., Wang Y., Huang J. Analysis of lipidomics profile of Carya cathayensis nuts and lipid dynamic changes during embryonic development. Food Chemistry. 2022;370 doi: 10.1016/j.foodchem.2021.130975. [DOI] [PubMed] [Google Scholar]
  14. Huang T., Zhang Y., Wang X., Zhang H., Chen C., Chen Q., Zhong Q. Comprehensive metabolite profiling reveals the dynamic changes of volatile and non-volatile metabolites in albino tea cultivar ‘Ming guan’ (MG) during white tea withering process. Food Research International. 2025;202 doi: 10.1016/j.foodres.2025.115784. [DOI] [PubMed] [Google Scholar]
  15. Huang W., Wu Z., Lu J., Shang S., Liu H., Ma Y., Kan Q., Chen Y., Cao Y. The comparative study of the quality characteristics of frozen litchi under different thawing temperatures and heat-transfer coefficient: Effects on thawing characteristics, physicochemical properties, nutritional characteristics, and eating quality. Food Science and Technology. 2025;226 doi: 10.1016/j.lwt.2025.117959. [DOI] [Google Scholar]
  16. Huang Y., Peng X., Chen Y., Wang Y., Ma J., Zhu M., Liu Z., Xiao Y. Decoding the dynamic evolution of volatile organic compounds of dark tea during solid-state fermentation with Debaryomyces hansenii using HS-SPME-GC/MS, E-nose and transcriptomic analysis. Food Science and Technology. 2025;223 doi: 10.1016/j.lwt.2025.117765. [DOI] [Google Scholar]
  17. Jiang C., Yu J., Zhu N., Zhou D., Yuan S., Lu M., Pan X., Dai L., Qi Y., Li X., Wu Z. Integrative omic and transgenic analyses reveal methyl jasmonate- and abscisic acid-responsive regulator CwbHLH2 that positively regulates terpenoid biosynthesis in curcuma wenyujin. Industrial Crops and Products. 2024;209 doi: 10.1016/j.indcrop.2024.118039. [DOI] [Google Scholar]
  18. Jiang S., Ni C., Chen G., Liu Y. A novel data fusion strategy based on multiple intelligent sensory technologies and its application in the quality evaluation of Jinhua dry-cured hams. Sensors and actuators. B. Chemical. 2021;344 doi: 10.1016/j.snb.2021.130324. [DOI] [Google Scholar]
  19. Lan T., Lv X., Zhao Q., Lei Y., Gao C., Yuan Q., Sun X., Liu X., Ma T. Optimization of strains for fermentation of kiwifruit juice and effects of mono- and mixed culture fermentation on its sensory and aroma profiles. Food Chemistry: X. 2023;17 doi: 10.1016/j.fochx.2023.100595. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Lan T., Wang J., Yuan Q., Lei Y., Peng W., Zhang M., Li X., Sun X., Ma T. Evaluation of the color and aroma characteristics of commercially available Chinese kiwi wines via intelligent sensory technologies and gas chromatography-mass spectrometry. Food Chemistry: X. 2022;15 doi: 10.1016/j.fochx.2022.100427. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Leng P., Yuan B., Guo Y. The role of abscisic acid in fruit ripening and responses to abiotic stress. Journal of Experimental Botany. 2013;65(16):4577–4588. doi: 10.1093/jxb/eru204. [DOI] [PubMed] [Google Scholar]
  22. Li P., Dai S.J., Zhao B., Zhang Y.S., Liao K., Xu F.…Leng P. Effect of low temperatures on pulp browning and endogenous abscisic acid and ethylene concentrations in peach (Prunus persica L.) fruit during post-harvest storage. The Journal of Horticultural Science and Biotechnology. 2014;89(6):686–692. doi: 10.1080/14620316.2014.11513138. [DOI] [Google Scholar]
  23. Li X., Peng W., Zhang M., Zhao Q., Fang Y., Sun X., Ma T. Mechanisms of texture and cell microstructure changes during post-ripening of ‘Cuixiang’ kiwifruit. Postharvest Biology and Technology. 2024;207 doi: 10.1016/j.postharvbio.2023.112596. [DOI] [Google Scholar]
  24. Lin J., Chen L., Wu W., Guo X., Yu C., Xu M., Nie G., Dun J., Li Y., Xu B., Wang L., Chen X., Gao W., Huang J. Single-cell RNA sequencing reveals a hierarchical transcriptional regulatory network of terpenoid biosynthesis in cotton secretory glandular cells. Molecular Plant. 2023;16(12):1990–2003. doi: 10.1016/j.molp.2023.10.008. [DOI] [PubMed] [Google Scholar]
  25. Mao J., Gao Z., Lin M., Zhang X., Ning X., Gong X., Lu Y., Chen L., Wang X. Targeted multi-platform metabolome analysis and enzyme activity analysis of kiwifruit during post-harvest ripening. Frontiers in Plant Science. 2023;14 doi: 10.3389/fpls.2023.1120166. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Meitzel T., Radchuk R., McAdam E.L., Thormählen I., Feil R., Munz E.…Borisjuk L. Trehalose 6-phosphate promotes seed filling by activating auxin biosynthesis. New Phytologist. 2021;229(3):1553–1565. doi: 10.1111/nph.16956. [DOI] [PubMed] [Google Scholar]
  27. Nardozza S., Boldingh H.L., Kashuba M.P., Feil R., Jones D., Thrimawithana A.H.…Richardson A.C. Carbon starvation reduces carbohydrate and anthocyanin accumulation in red-fleshed fruit via trehalose 6-phosphate and MYB27. Plant, Cell & Environment. 2020;43(4):819–835. doi: 10.1111/pce.13699. [DOI] [PubMed] [Google Scholar]
  28. Niu Y., Ye L., Wang Y., Shi Y., Liu Y., Luo A. Transcriptome analysis reveals salicylic acid treatment mitigates chilling injury in kiwifruit by enhancing phenolic synthesis and regulating phytohormone signaling pathways. Postharvest Biology and Technology. 2023;205 doi: 10.1016/j.postharvbio.2023.112483. [DOI] [Google Scholar]
  29. Payá C., Belda-Palazón B., Vera-Sirera F., Pérez-Pérez J., Jordá L., Rodrigo I.…Lisón P. Signalling mechanisms and agricultural applications of (Z)-3-hexenyl butyrate-mediated stomatal closure. Horticulture Research. 2024;11(1) doi: 10.1093/hr/uhad248. uhad248-145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Pereira T.M., Franco D.P., Vitorio F., Kummerle A.E. Coumarin compounds in medicinal chemistry: Some important examples from the last years. Current Topics in Medicinal Chemistry. 2018;18(2):124–148. doi: 10.2174/1568026618666180329115523. [DOI] [PubMed] [Google Scholar]
  31. Salvi P., Kamble N.U., Majee M. Stress-inducible galactinol synthase of chickpea (CaGolS) is implicated in heat and oxidative stress tolerance through reducing stress-induced excessive reactive oxygen species accumulation. Plant and Cell Physiology. 2018;59(1):155–166. doi: 10.1093/pcp/pcx170. [DOI] [PubMed] [Google Scholar]
  32. Sharma A., Shahzad B., Rehman A., Bhardwaj R., Landi M., Zheng B. Response of phenylpropanoid pathway and the role of polyphenols in plants under abiotic stress. Molecules (Basel, Switzerland) 2019;24(13):2452. doi: 10.3390/molecules24132452. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Smeekens S., Hellmann H.A. Sugar sensing and signaling in plants. Frontiers in Plant Science. 2014;5:113. doi: 10.3389/fpls.2014.00113. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Stec M.G.H., Hodgson J.A., Macrae E.A., Triggs C.M. Role of fruit firmness in the sensory evaluation of kiwifruit (Actinidia deliciosa cv Hayward) Journal of the Science of Food and Agriculture. 1989;47(4):417–433. doi: 10.1002/jsfa.2740470404. [DOI] [Google Scholar]
  35. Su M., Zhuang L., Zhang Q., Zhang Q., Wang M., Sun W.…Lyu D. Lipid dynamics of “Fenjiao” bananas (Musa ABB pisang Awak) during post-ripening based on lipidomics analysis. Postharvest Biology and Technology. 2024;207 doi: 10.1016/j.postharvbio.2023.112611. [DOI] [Google Scholar]
  36. Sun F., Chen H., Chen D., Tan H., Huang Y., Cozzolino D. Lipidomic changes in banana (Musa cavendish) during ripening and comparison of extraction by folch and bligh-dyer methods. Journal of Agricultural and Food Chemistry. 2020;68(40):11309–11316. doi: 10.1021/acs.jafc.0c04236. [DOI] [PubMed] [Google Scholar]
  37. Thimmappa R., Geisler K., Louveau T., O'Maille P., Osbourn A. Triterpene biosynthesis in plants. Annual Reviews. 2014:225–257. doi: 10.1146/annurev-arplant-050312-120229. [DOI] [PubMed] [Google Scholar]
  38. Tholl D. In: Biotechnology of isoprenoids. Schrader J., Bohlmann J., editors. Springer International Publishing AG; 2015. Biosynthesis and biological functions of terpenoids in plants; pp. 63–106. [DOI] [Google Scholar]
  39. Tian X., Zhu L., Yang N., Song J., Zhao H., Zhang J., Ma F., Li M. Proteomics and metabolomics reveal the regulatory pathways of ripening and quality in post-harvest kiwifruits. Journal of Agricultural and Food Chemistry. 2021;69(2):824–835. doi: 10.1021/acs.jafc.0c05492. [DOI] [PubMed] [Google Scholar]
  40. Wang J., Vanga S.K., Raghavan V. High-intensity ultrasound processing of kiwifruit juice: Effects on the ascorbic acid, total phenolics, flavonoids and antioxidant capacity. LWT. 2019;107:299–307. doi: 10.1016/j.lwt.2019.03.024. [DOI] [Google Scholar]
  41. Wang P., Zhan P., Liu R., He W., Gao G., Tian H. Characterization of the formation of key flavor volatiles in kiwifruit (Actinidia deliciosa) during storage by integrating. European Food Research and Technology. 2024;250(4):1017–1029. doi: 10.1007/s00217-023-04440-5. [DOI] [Google Scholar]
  42. Wang R., Martin P., McAtee P.A., Schaffer R.J., Burdon J. New insights into the storage performance of ‘Hayward’ kiwifruit from a comparison of three cultivars. New Zealand Journal of Crop and Horticultural Science. 2024;52(1):76–92. doi: 10.1080/01140671.2022.2096083. [DOI] [Google Scholar]
  43. Wang S., Qiu Y., Zhu F. Kiwifruit (Actinidia spp.): A review of chemical diversity and biological activities. Food Chemistry. 2021;350 doi: 10.1016/j.foodchem.2020.128469. [DOI] [PubMed] [Google Scholar]
  44. Wang Y., Li Y., Yang S., Wu Z., Shen Y. Gaseous ozone treatment prolongs the shelf-life of fresh-cut kiwifruit by maintaining its ascorbic acid content. LWT. 2022;172 doi: 10.1016/j.lwt.2022.114196. [DOI] [Google Scholar]
  45. Wang Y., Wang D., Lv Z., Zeng Q., Fu X., Chen Q., Luo Z., Luo C., Wang D., Zhang W. Analysis of the volatile profiles of kiwifruits experiencing soft rot using E-nose and HS-SPME/GC–MS. LWT. 2023;173 doi: 10.1016/j.lwt.2022.114405. [DOI] [Google Scholar]
  46. Xiao Y., Chen H., Chen Y., Ho C., Wang Y., Cai T., Li S., Ma J., Guo T., Zhang L., Liu Z. Effect of inoculation with different Eurotium cristatum strains on the microbial communities and volatile organic compounds of fu brick tea. Food Research International. 2024;197(Pt 1) doi: 10.1016/j.foodres.2024.115219. [DOI] [PubMed] [Google Scholar]
  47. Xiao Y., He C., Chen Y., Ho C., Wu X., Huang Y., Gao Y., Hou A., Li Z., Wang Y., Liu Z. UPLC–QQQ–MS/MS-based widely targeted metabolomic analysis reveals the effect of solid-state fermentation with Eurotium cristatum on the dynamic changes in the metabolite profile of dark tea. Food Chemistry. 2022;378 doi: 10.1016/j.foodchem.2021.131999. [DOI] [PubMed] [Google Scholar]
  48. Xiong S., Sun X., Tian M., Xu D., Jiang A. 1-Methylcyclopropene treatment delays the softening of Actinidia arguta fruit by reducing cell wall degradation and modulating carbohydrate metabolism. Food Chemistry. 2023;411 doi: 10.1016/j.foodchem.2023.135485. [DOI] [PubMed] [Google Scholar]
  49. Yan H., Chen H., Zhao J., Yao T., Ding X. Postharvest H2O2 treatment affects flavor quality, texture quality and ROS metabolism of ‘Hongshi’ kiwifruit fruit kept at ambient conditions. Food Chemistry. 2023;405 doi: 10.1016/j.foodchem.2022.134908. [DOI] [Google Scholar]
  50. Yang F., Zhao R., Suo J., Ding Y., Tan J., Zhu Q., Ma Y. Understanding quality differences between kiwifruit varieties during softening. Food Chemistry. 2024;430 doi: 10.1016/j.foodchem.2023.136983. [DOI] [PubMed] [Google Scholar]
  51. Yang T., Deng L., Wang Q., Sun C., Ali M., Wu F., Zhai H., Xu Q., Xin P., Cheng S., Chu J., Huang T., Li C.-B., Li C. Tomato CYP94C1 inactivates bioactive JA-Ile to attenuate jasmonate-mediated defense during fruit ripening. Molecular Plant. 2024;0(0) doi: 10.1016/j.molp.2024.02.004. [DOI] [PubMed] [Google Scholar]
  52. Yang Y., Chen L., Wang C., Peng H., Yin W., Li R., Liu C., Ren X., Ding Y. Pathogenic fungi diversity of ‘CuiXiang’ kiwifruit black spot disease during storage. Horticulturae. 2022;8(1):13. doi: 10.3390/horticulturae8010013. [DOI] [Google Scholar]
  53. Yuan H., Cao G., Hou X., Huang M., Du P., Tan T.…Luo J. Development of a widely targeted volatilomics method for profiling volatilomes in plants. Molecular Plant. 2022;15(1):189–202. doi: 10.1016/j.molp.2021.09.003. [DOI] [PubMed] [Google Scholar]
  54. Zhan Z., Gao Y., Chen Y., Xu M., Wang H., Cheng J., Zhang B. Comprehensive metabolomic profiling of aroma-related volatiles in table grape cultivars across developmental stages. Food Quality and Safety. 2025;9 doi: 10.1093/fqsafe/fyaf013. [DOI] [Google Scholar]
  55. Zhang G., Liu W., Gu Z., Wu S., Yilan E., Zhou W., Lin J., Xu L. Roles of the wound hormone jasmonate in plant regeneration. Journal of Experimental Botany. 2023;74(4):1198–1206. doi: 10.1093/jxb/erab508. [DOI] [PubMed] [Google Scholar]
  56. Zhang P., Jackson E., Li X., Zhang Y. Salicylic acid and jasmonic acid in plant immunity. Horticulture Research. 2025;12(7) doi: 10.1093/hr/uhaf082. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary material

mmc1.docx (1.7MB, docx)

Data Availability Statement

All data used for the research were described in the article or supplementary materials.

Articles from Food Chemistry: X are provided here courtesy of Elsevier

RESOURCES