Abstract
This study systematically evaluated six white grape cultivars and their wines from Changli, China, through multi-analytical techniques (HPLC, LC-MS/MS, HS-SPME -GC-MS, etc.) to compare oenological parameters, organic acid profiles, phenolic compositions, and aromatic volatiles. Results indicated that the total sugar contents in Aranèle (202.11 g/L) and Viognier (201.12 g/L) berries were significantly higher than those in other varieties. Compared with other varieties, Roussanne grape juice and wine had a higher content of phenolic components, and the fermented Chardonnay wine exhibited a higher proanthocyanidin content. In the flavor profile of the wines, the contents of ethyl octanoate, isoamyl acetate, and α-ionene in Semillon wine (total volatile components in Semillon: 56,147.3 μg/L) were significantly higher than those in the other wines. Additionally, Aranèle wine had the highest phenethyl alcohol content. The principal component analysis (PCA), performed on combined normalized data of organic acids, phenolic components, and volatile compounds, revealed distinct clustering of the six white wines. The first and second principal components explained 41.63% and 43.37% of the total variance, respectively, demonstrating clear differentiation among the six white wines. Sensory analysis revealed no distinct differences in appearance among the six white wines, whereas significant variations were observed in aroma and taste profiles.
Keywords: white grape cultivars, organic acids, phenolic substances, volatile compounds
1. Introduction
Changli County (39°25′–39°48′ N, 118°45′–119°20′ E) is situated in the mountainous terrain of northeastern Hebei Province and is in the same golden zone as Bordeaux, France [1]. The region’s favorable location, distinctive topography, fertile soil, and unique geological environment provide strong support for high-quality wine production in Changli [1]. The location has an annual average temperature of 11 °C and a frost-free duration of 186 days. The global shift toward low-alcohol and refreshing wines, driven by evolving consumer preferences for healthier lifestyles and sensory diversity, has precipitated a surge in demand for white wines [2]. This trend illustrates the importance for enhanced quality standards in white wine production, particularly in regions like Changli County. According to recent data, white wine now accounts for 49% of global production, reflecting its rising prominence in the market [2]. To meet these heightened expectations, the quality characteristics of white wine—dictated by organic acid profiles, phenolic compounds, and volatile aroma—must align with consumer perceptions of freshness, complexity, and balance.
The quality characteristics of white wine are influenced by its organic acid, phenolic substances, and volatile compounds. Among these, organic acids not only define the wine’s acidity profile but also significantly contribute to flavor complexity. Moderate acid levels enhance palatability by balancing sweetness and bitterness, whereas excessive acidity disrupts flavor equilibrium and compromises overall quality. Tang et al. demonstrated that organic acid and polyphenol fingerprints could serve as reliable biomarkers for wine varietal authentication and geographical traceability [3]. Phenolic compounds can be divided into non-flavonoid derivatives (e.g., hydroxycinnamic acids and their esters) characterized by benzene ring modifications and flavonoid subclasses such as flavanols, flavonols, and anthocyanins [4,5]. Phenolic compounds can serve as critical chemical biomarkers for verifying wine, exhibiting distinct variability influenced by grape variety, terroir factors, and enological techniques [6]. Wine aroma, a critical determinant of quality, mainly includes alcohols, aldehydes, ketones, acids, esters, terpenes, etc., whose composition defines style diversity of wines [7].
The relationship between grapevine cultivars and their chemical fingerprints is the cornerstone of varietal expression [8,9]. Grape genotype primarily determines the aromatic and phenolic profiles of different varieties, thereby conferring distinct sensory characteristics to their wines, while the synthesis and accumulation of these compounds are modulated by developmental stages and environmental growing conditions [8,9].
To select suitable white grape cultivars for Changli’s terroir and develop high-quality wines, an introduction trial (2010–2012) was systematically conducted with internationally recognized cultivars, including Chardonnay, Viognier, Riesling, Aranèle, Roussanne, and so on [10]. While preliminary assessments of growth-fruiting characteristics and disease susceptibility provided foundational data, the systematic evaluation was insufficient for comprehensive cultivar screening. Notably, organic acid profiles (citric, malic, and tartaric acids), phenolic compounds, and volatile aroma exhibited significant variability across cultivars, directly influencing wine sensory attributes.
To assess the adaptability and performance of white grape cultivars in Changli’s terroir, this study systematically investigated physicochemical properties, organic acid profiles (citric and malic acids), phenolic composition, and volatile aroma of white grapes and wines derived from six cultivars. The findings enabled a comprehensive evaluation of enological quality, revealing cultivar-specific traits. This research provides a data-driven framework for optimizing grape selection, vineyard management, and winemaking strategies in Changli, thereby advancing regional viticulture through cultivar-specific innovation.
2. Materials and Methods
2.1. Grape Sampling and Vinification Techniques
Six white grape cultivars (Chardonnay, Viognier, Sémillon, Italian Riesling, Aranèle, and Roussanne) were harvested in October 2022 from a single commercial vineyard (Bodega-Langes, Changli County, China). All vines had similar age, yield, and cultivation management practices to ensure consistency [10]. After mechanical destemming and crushing, the grape juice was fermented in 20 L stainless-steel containers with three replicates per trial. A 200 mL aliquot of squeezed grape juice was immediately collected and stored at −30 °C for subsequent analysis.
The grape juice sugar content was adjusted to 23 °Brix by sucrose addition, followed by 30 mg/L pectinase addition and potassium metabisulfite (KMS) addition (to adjust free SO2 to 30 mg/L). The must was cold-settled at 4 °C, then racked to remove residual solids. Saccharomyces cerevisiae QA23 (Lallemand, Montreal, QC, Canada) was inoculated at 200 mg/L, and fermentation proceeded at 16 °C. At the end of alcohol fermentation (residual sugar < 4 g/L), the wines were transferred into another container under nitrogen atmosphere, free SO2 was adjusted to 40 mg/L, and stored at 16 °C.
2.2. Physicochemical Analysis
The physicochemical properties of juices and wines were systematically analyzed following standardized protocols. Total sugar, alcohol concentration, residual sugar, total acidity, volatile acidity, and pH were quantified according to the method described by Meng et al. [11]. Each sample was analyzed in triplicate.
2.3. Determination of Phenolic Compounds (Total Phenols, Flavonoids, Tannins, and Flavan-3-Ols)
Berries from each treatment group were randomly selected, manually destemmed, deseeded, and ground. A 10 g sample was accurately weighed and extracted with 100 mL of 60% methanol (v/v, containing 0.1% HCl) using an ultrasonic bath (40 KHz, 200 W) for 40 min. The extract was centrifuged at 4 °C for 15 min (8500 r/min), and the supernatant was filtered through a 0.45 μm membrane prior to analysis.
Total phenol content (TPC) in wines and extracts was determined by the Folin-Ciocalteau colorimetric method [12]. Total flavonoids content (TFo) and total tannins content (TTC) were determined according to the method reported by Ju [12]. Total flavan-3-ol content (TFa) was determined by the p-DMACA-HCl method [13].
2.4. Determination of Organic Acids
Organic acids in grape juice and wine were profiled using an Agilent 1200 Series HPLC system (Agilent Technologies, Santa Clara, CA, USA) with a C18 reversed-phase column (4.6 × 250 mm, 5 μm). Analysis was performed under isocratic elution with a mobile phase of 0.02 M diammonium hydrogen phosphate buffer (pH 2.45) at a flow rate of 1.0 mL/min, and detection at 210 nm. Samples were filtered (0.22 μm) and injected at 20 μL. Data were acquired and processed using OpenLAB CDS ChemStation software (B.04).
2.5. HPLC–MS/MS Analysis of Phenols
Phenolic compounds were analyzed according to a validated method by Qin et al. [14]. An Agilent 1290 Infinity LC-MS/MS system (equipped with an ESI source) was employed, coupled with a 6420 triple quadrupole mass spectrometer (Agilent Technologies, Santa Clara, CA, USA). Separation was conducted on a Poroshell 120 SB-C18 column (2.1 × 75 mm, 2.7 μm, Agilent Technologies, Santa Clara, CA, USA) at 30 °C. Mobile phases (0.1% (v/v) formic acid in water (A) and acetonitrile containing 0.1% (v/v) formic acid (B)) were used with a flow rate of 0.25 mL/min. An injection volume of 5 μL was used. A gradient program consisting of the following steps was applied: 0–3 min at 5% B; 3–6 min at 20% B; 6–8 min at 30% B; 8–10 min at 40% B; 10–15 min at 50% B; 15–17 min at 5% B.
Negative-ion electrospray ionization (ESI) was configured with nitrogen gas (11 L/min) at 300 °C, a nebulizer pressure of 35 psi, and a mass scan range of 100–1500 m/z. Quantitative analysis was performed using multiple reaction monitoring (MRM) to improve sensitivity and selectivity for targeted analytes. Prior to chromatographic injection, samples were processed through a 0.22 μm membrane filter.
Phenolic compounds were characterized by retention time alignment, molecular ion mass accuracy, and fragment ion patterns using reference standards. Quantitative determinations were carried out via external calibration curves generated from certified reference materials under standardized chromatographic conditions. Data processing and analysis were executed using MassHunter Qualitative Analysis B 7.0 (Agilent Technologies).
2.6. Analysis of Volatile Compounds
Volatile compounds of grape juice and wine were analyzed using Agilent Technologies equipment (Santa Clara, CA, USA): an Agilent GC 7890B gas chromatograph, coupled with a 5977A MS, an Agilent autosampler, and an HP-INNOWax capillary column (30 m × 0.25 mm × 0.5 µm) after centrifugation at 8000 rpm for 15 min [14].
Headspace-solid phase microextraction (HS-SPME) was employed to extract volatile compounds from the sample matrix. Quantitative and qualitative analysis was subsequently performed using gas chromatography-mass spectrometry (GC-MS). Each sample (8 mL supernatant) was spiked with 2.4 g NaCl and 8 µL 2-octanol (1000 µg/L) as an internal standard, transferred to a 15 mL vial, and sealed. The vial was heated at 50 °C for 30 min on a temperature-controlled platform, followed by HS-SPME extraction with a 50/30 µm DVB/CAR/PDMS fiber (Supelco, Bellefonte, PA, USA) for 30 min. GC-MS analysis was conducted in splitless mode using high-purity helium (99.999% purity) at 1 mL/min. The column temperature program initiated at 50 °C (2 min) and increased to 220 °C at 3 °C/min (1 min hold) and then to 235 °C at 8 °C/min (1 min hold). MS parameters included an electron ionization (EI) source (70 eV) with interface and ion source temperatures at 250 °C and 230 °C, respectively. Mass spectra were acquired over m/z 50–550 using a quadrupole temperature of 150 °C. All analyses included three technical replicates.
Volatile compounds were identified through retention index comparison using n-alkane standards (C8–C30, Sigma-Aldrich, St. Louis, MO, USA) and mass spectral matching with pure reference compounds. All mass spectra were further validated against the NIST 14 mass spectral library. Semi-quantification was conducted via the internal standard method (2-octanol) with standard curves. The results are expressed as relative concentrations.
2.7. Sensory Analysis of Wine
Sensory evaluation of wine was conducted to study differences among distinct single-varietal white wines, with all assessments performed after one year of aging. The panel comprised 10 trained wine tasters (5 females, 5 males; aged 20–45), following the official method of the International Federation of Brewers (IFB), in a controlled room (20 ± 2 °C), at the College of Food Science and Biology, Hebei University of Science and Technology. Tasting sessions occurred at 10:00 a.m., with wines randomly coded and presented left-to-right.
Each sommelier was given a specific tasting note, in which all sensory attributes used are selected according to the tasting descriptor of white wine [7]. According to the increase in intensity, each attribute was graded from 0 to 10. We asked each sommelier to evaluate the appearance (color and clarity), aroma (purity and strength), taste (acidity, balance, persistence, and astringency) characteristics, and the typicality of wine.
2.8. Statistical Analysis
Data are expressed as mean ± standard deviation (SD) of three technical replicates. One-way analysis of variance (ANOVA) was performed via IBM SPSS Statistics 22 (SPSS Inc., Chicago, IL, USA) to determine the significant differences between different varieties. Duncan’s multiple range test (p < 0.05) was applied for post hoc pairwise comparisons, with significant differences denoted by lowercase. All graphs were generated using Origin 2018 (OriginLab Corporation, Northampton, MA, USA).
3. Results and Discussion
3.1. Berry Attributes and Oenological Parameters of Wines
Physicochemical properties of six grape varieties before and after fermentation are shown in Figure 1. The total sugar content decreased remarkably during fermentation, primarily due to S. cerevisiae metabolizing sugars through glycolysis and the TCA cycle [14]. Significant variations in total sugar contents were observed across the six grape varieties: Aranèle (202.11 g/L) and Viognier (201.12 g/L) exhibited the highest concentrations. The alcohol contents of the six kinds of wine ranged from 12.47% to 12.87%.
Figure 1.
The grape attributes (A) and basic chemical profiles of wines (B) from six varieties. Note: Grape juice (no high-grade sucrose added). Different letters represent significant differences between the treatments according to Duncan’s test (p < 0.05). Abbreviations: TS, total sugar; TA, total acid; RS, residual sugar.
The acidity of wine is important for enhancing its freshness [3,15,16]. There were significant differences in total acid content among six types of white grapes and their corresponding wines. The total acid content of Roussanne grape (8.23 g/L) was the highest, being 1.40 times higher than that of Viognier grape. After fermentation, the total acid contents of Semillon and Italian Riesling wine increased compared with that of grape juice, but those for other kinds of wine decreased.
3.2. TPC, TTC, TFo and TFa Levels in Grapes
The total phenols, total flavonoids, total tannins, and total flavan-3-ol contents of the skin and juice are shown in Figure 2. Differences among the six grape varieties were notable.
Figure 2.
Polyphenols contents in grape skin (A) and grape juice (B) under various treatments. Note: Different letters represent significant differences between the treatments according to Duncan’s test (p < 0.05). Abbreviations: TPC, total phenolic content; TFa, total flavan-3-ol content; TFo, total flavonoid content; TTC, total tannin content.
The grape fruit was rich in phenolic compounds, which can prevent microbial spoilage, control fermentation rate, and provide aroma for fermented juice during fermentation [15]. The total phenol content (TPC) in the skin of Roussanne grapes was the highest (15.31 mg/L), being significantly higher than those of other varieties (p < 0.05), while the TPC in the skin of Aranèle grapes was the lowest. There were no significant differences in the TPCs of grape juice for the six grapes, with these values ranging between 0.21 and 0.27 mg/L. Tannin is responsible for determining the dryness, roughness, and pucker of the wine, which gives wine astringency [17]. The total tannin contents (TTCs) in skins of the Roussanne and Viognier grapes were high (24.80 mg/L and 25.25 mg/L, respectively), being significantly higher than those of other varieties (p < 0.05). There were no significant differences in the TTCs of grape juice for the six kinds of grape, which ranged from 0.22 to 0.31 mg/L. The total flavonoid content (TFo) and total flavan-3-ol content (TFa) in skin were the highest in Roussanne and lowest in Aranèle, and these components were hardly detected in juice.
3.3. Organic Acid Content in Juice and Wine
Nine kinds of organic acid were determined via HPLC. As shown in Table 1, the main organic acids in grape juices were malic acid and tartaric acid (accounting for 77.79% of the total content), which was consistent with the previous research results [16]. The total organic acid content in Roussanne grape juice (5.69 mg m/L) was the highest, predominantly consisting of malic acid, tartaric acid, and citric acid.
The primary organic acids in wine were malic acid, tartaric acid, and succinic acid, accounting for 74.81% of the total content. The total organic acid content in Roussanne wine (8.75 mg/L) was significantly higher than those of other varieties, followed by Aranèle wine (7.95 mg m/L) and Italian Riesling wine (7.81 mg/L), which was mainly due to the high succinic acid content. There were significant (p < 0.05) differences between the total organic acid contents in the juice and wine of each variety.
Lactic acid increased the complexity and fruity flavor of wine, reduced acidity concurrently and improved the stability and nutritional value of fermented juice [18]. In this experiment, lactic acid was produced after the fermentation of grape juice, and the lactic acid content in Chardonnay wine was the highest (0.95 mg/L). Higher lactic acid content might indicate malolactic fermentation or the degradation of carbohydrates, tartaric acid, and glycerol. The malic acid contents in the six varieties decreased after fermentation. Wines had slightly higher malic acid contents with the addition of Chardonnay and Roussanne. It has been suggested that this could create a pungent taste at an excessive level [19]. Compared to juice, the tartaric acid content in Italian Riesling wine increased slightly. The citric acid content increased slightly in Aranèle, Chardonnay, and Italian Riesling after alcohol fermentation.
3.4. Flavonoids, Phenolic Acids, and Stilbenoid
Single phenolic compounds are important health components in wine. Although the concentration of phenolic components in white wine is lower than in red wine, they have important antioxidant, anti-aging, and anti-cancer activities, which also affect the stability and taste of wine [20]. The primary phenolic compounds identified via LC-MS/MS in six grape juices and wines are displayed in Table 2. A total of 19 species were detected in this experiment, comprising 6 flavonoids, 12 phenolic acids, and 1 stilbenoid.
The total polyphenol concentration in wine was 195.49 mg/L, which was 3.32 times higher than that in grape juice (58.87 mg/L). Chardonnay wine had the highest polyphenol content (37.21 mg/L). In this experiment, quercetin was the most abundant compound in grape juice, confirming the previous findings of Restuccia et al. [21]. The proanthocyanidin, catechin, and protocatechuic acid contents in wine were higher, consistent with previous research results [4,5,7,22].
Flavonoids and Flavan-3-ols can stabilize the color of wine and increase its astringency and bitterness [23]. The total flavonoids and Flavan-3-ols content in Viognier juice was the highest (9.46 mg/L), as shown in Table 2, primarily due to the high content of proanthocyanidins, which was not detected in other grape juices. After fermentation, the procyanidin content increased, reaching 26.31 mg/L in Chardonnay wine. Flavonoid quercetin played an important role in determining the color stability of wine. After fermentation, the flavonoid quercetin content in wines decreased except for in Viognier and Italian Riesling wines. The decrease in flavonols and Flavan-3-ols content might be due to co-pigmentation phenomena [21].
Table 1.
The contents of nine organic acids in six kinds of white grape juice and wine (g/L).
| Number | Organic Acids | Grape Juice | Wine | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | ||
| O01 | Oxalic acid | 0.14 ± 0.01 a | 0.19 ± 0.01 a | 0.35 ± 0.03 c | 0.35 ± 0.06 c | 0.20 ± 0.03 a,b | 0.27 ± 0.02 b | 0.15 ± 0.01 c | ND | ND | 0.08 ± 0.02 b | ND | 0.04 ± 0.00 a |
| O02 | Tartaric acid | 0.64 ± 0.04 a | 1.77 ± 0.02 c | 1.62 ± 0.02 b | 1.54 ± 0.04 b | 2.37 ± 0.02 e | 1.91 ± 0.08 d | 0.96 ± 0.01 a | 2.02 ± 0.03 b | 1.66 ± 0.03 b | 3.13 ± 0.52 d | 2.00 ± 0.21 b | 2.45 ± 0.01 c |
| O03 | Formic acid | ND | 0.55 ± 0.06 b | 0.46 ± 0.03 a,b | 0.54 ± 0.01 b | 0.43 ± 0.02 a | 0.37 ± 0.07 a | 0.80 ± 0.01 c,d | 0.51 ± 0.01 b | 0.87 ± 0.02 d | 0.72 ± 0.01 c | 0.82 ± 0.17 c,d | 0.33 ± 0.01 a |
| O04 | Malic acid | 2.65 ± 0.06 d | 1.65 ± 0.03 b | 2.65 ± 0.05 d | 1.65 ± 0.04 b | 1.32 ± 0.01 a | 2.41 ± 0.09 c | 2.30 ± 0.03 c | 1.33 ± 0.01 a | 2.26 ± 0.03 c | 1.50 ± 0.01 b | 1.27 ± 0.16 a | 1.33 ± 0.01 a |
| O05 | Shikimic acid | 0.01 ± 0.00 | 0.02 ± 0.00 | ND | ND | ND | ND | 0.01 ± 0.00 | 0.02 ± 0.00 | ND | ND | ND | ND |
| O06 | Acetic acid | 0.01 ± 0.00 a | 0.03 ± 0.01 a | 0.05 ± 0.01 b | 0.04 ± 0.01 a,b | 0.02 ± 0.00 ab | 0.02 ± 0.00 a,b | ND | 0.05 ± 0.00 | 0.07 ± 0.01 | 0.10 ± 0.04 | 0.08 ± 0.01 | 0.07 ± 0.05 |
| O07 | Citric acid | 0.43 ± 0.03 b | 0.26 ± 0.04 a | 0.58 ± 0.02 c | 0.46 ± 0.02 b | 0.17 ± 0.04 a | 0.43 ± 0.08 b | 1.11 ± 0.03 d | 0.29 ± 0.02 b | 0.27 ± 0.01 b | 0.17 ± 0.02 a | 0.29 ± 0.01 b | 0.33 ± 0.01 c |
| O08 | Butanedioic acid | ND | ND | ND | ND | ND | ND | 0.01 ± 0.00 a | 3.02 ± 0.21 c | 2.85 ± 0.01 c | 0.01 ± 0.00 a | 2.84 ± 0.08 c | 1.79 ± 0.03 b |
| O09 | Lactic acid | ND | ND | ND | ND | ND | ND | 0.95 ± 0.01 c | 0.71 ± 0.27 b,c | 0.77 ± 0.03 b,c | 0.71 ± 0.18 b,c | 0.52 ± 0.03 b | 0.17 ± 0.17 a |
Note: Different letters in the same column indicate statistically significant differences (p < 0.05). Values are means of triplicate determination (n = 3) ± S.D; ND: not detected.
Table 2.
The contents of 19 kinds of monomeric phenolic substances in 6 kinds of white grape juice and wine (mg/L).
| Number | Phenolic Substances | Grape Juice | Wine | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | ||
| Phenolic acids | |||||||||||||
| P01 | Gallic acid | ND | ND | ND | ND | ND | 0.04 ± 0.00 a | 0.09 ± 0.00 b | 0.30 ± 0.01 d | 0.39 ± 0.01 e | 0.21 ± 0.01 c | 0.05 ± 0.00 a | 0.04 ± 0.00 a |
| P02 | Furoic acid | 0.05 ± 0.00 c | 0.03 ± 0.00 b | 0.03 ± 0.00 b | ND | 0.06 ± 0.00 d | 0.15 ± 0.01 e | ND | 0.10 ± 0.00 d | 0.03 ± 0.00 b | ND | 0.04 ± 0.00 c | 0.02 ± 0.00 a |
| P03 | Gentisic acid | 0.09 ± 0.00 a | 0.09 ± 0.00 a | 0.09 ± 0.00 a | 0.35 ± 0.01 b | 0.09 ± 0.00 a | 0.08 ± 0.00 a | 0.20 ± 0.01 c | 0.27 ± 0.01 d | 0.78 ± 0.03 e | 0.21 ± 0.01 c | 0.17 ± 0.01 b | 0.12 ± 0.00 a |
| P04 | Protocatechuic acid | ND | ND | ND | ND | ND | ND | 0.50 ± 0.02 a | 0.55 ± 0.02 c,d | 0.51 ± 0.02 a,b | 0.56 ± 0.02 d | 0.53 ± 0.02 b,c | 0.50 ± 0.03 a |
| P05 | 2,4-Dihydroxybenzoic acid | 1.36 ± 0.06 a | 1.40 ± 0.07 a | 1.34 ± 0.06 a | 1.47 ± 0.07 a | 1.34 ± 0.06 a | 1.39 ± 0.06 a | 2.59 ± 0.12 c | 2.45 ± 0.12 b | 2.69 ± 0.13 c | 2.90 ± 0.14 d | 2.25 ± 0.11 a | 2.39 ± 0.12 b |
| P06 | Vanillic acid | 0.50 ± 0.02 b | 0.50 ± 0.02 b | 1.10 ± 0.05 c | ND | 0.50 ± 0.02 b | ND | 0.27 ± 0.01 b | 0.29 ± 0.01 c | 0.44 ± 0.02 e | 0.32 ± 0.01 d | 0.15 ± 0.01 a | 0.27 ± 0.01 b |
| P07 | Syringic acid | ND | ND | ND | ND | ND | ND | 0.18 ± 0.01 b | 0.15 ± 0.01 a | 0.19 ± 0.01 b | 0.20 ± 0.01 c | 0.15 ± 0.01 a | 0.15 ± 0.01 a |
| P08 | Salicylic acid | 1.13 ± 0.05 a,b | 1.06 ± 0.05 a | 0.96 ± 0.04 a | 1.28 ± 0.06 b | 0.97 ± 0.04 a | 1.02 ± 0.05 a | 1.18 ± 0.06 a | 1.42 ± 0.07 c | 1.57 ± 0.01 d | 1.41 ± 0.07 c | 1.42 ± 0.07 c | 1.30 ± 0.07 b |
| P09 | Chlorogenic acid | 0.12 ± 0.00 a | 0.17 ± 0.01 b | 0.16 ± 0.01 b | 0.17 ± 0.01 b | 0.14 ± 0.01 a,b | 0.32 ± 0.02 c | 0.20 ± 0.01 c | 0.16 ± 0.00 a | 0.20 ± 0.01 c | 0.18 ± 0.01 b | 0.21 ± 0.01 c | 0.23 ± 0.01 d |
| P10 | Caffeic acid | 0.07 ± 0.00 d | 0.05 ± 0.00 b,c | 0.05 ± 0.00 b | 0.06 ± 0.00 c | ND | 0.05 ± 0.00 b,c | 0.47 ± 0.02 c | 0.85 ± 0.04 e | 0.33 ± 0.02 b | 0.15 ± 0.01 a | 0.75 ± 0.04 d | 0.47 ± 0.02 c |
| P11 | p-Hydroxycinnamic acid | ND | ND | ND | ND | ND | 0.03 ± 0.00 a | 0.16 ± 0.00 d | 0.19 ± 0.01 e | 0.15 ± 0.01 c | 0.02 ± 0.00 a | 0.11 ± 0.01 b | 0.02 ± 0.00 a |
| P12 | Ferulic Acid | 0.33 ± 0.01 b | 0.34 ± 0.01 b | 0.33 ± 0.01 b | 0.30 ± 0.01 b | 0.31 ± 0.01 b | 0.08 ± 0.00 a | 0.54 ± 0.02 a | 0.64 ± 0.03 b | 0.75 ± 0.03 c | 0.66 ± 0.03 b | 0.66 ± 0.03 b | 0.54 ± 0.03 a |
| Flavonols | |||||||||||||
| P13 | Rutin | ND | 0.01 ± 0.00 a | ND | 0.02 ± 0.00 a | ND | 0.10 ± 0.00 b | 0.02 ± 0.00 a | 0.02 ± 0.00 a | ND | ND | 0.03 ± 0.00 b | 0.10 ± 0.01 c |
| P14 | Quercitrin | 0.09 ± 0.00 b | ND | 0.11 ± 0.00 c | 0.04 ± 0.00 a | 0.08 ± 0.00 b | 0.05 ± 0.00 a | 0.04 ± 0.00 c | 0.04 ± 0.00 c | 0.05 ± 0.00 d | 0.03 ± 0.00 b | 0.05 ± 0.00 e | 0.03 ± 0.00 a |
| P15 | Quercetin | 3.09 ± 0.15 c | 0.96 ± 0.04 a | 0.78 ± 0.03 a | ND | ND | 2.25 ± 0.11 b | 0.78 ± 0.03 f | 0.47 ± 0.02 d | 0.01 ± 0.00 a | 0.20 ± 0.01 b | 0.41 ± 0.02 c | 0.75 ± 0.04 e |
| flavan-3-ols | |||||||||||||
| P16 | Catechin | ND | ND | ND | ND | ND | 0.03 ± 0.00 a | 0.79 ± 0.04 e | 0.82 ± 0.04 e | 0.57 ± 0.02 c | 0.46 ± 0.02 a | 0.66 ± 0.03 d | 0.51 ± 0.03 b |
| P17 | Procyanidin | ND | ND | ND | 9.41 ± 0.47 a | ND | ND | 26.31 ± 1.31 e | 18.24 ± 0.91 c | 13.40 ± 0.66 a | 15.27 ± 0.76 b | 15.01 ± 0.75 b | 22.09 ± 1.10 d |
| P18 | L-Epicatechin | ND | 0.04 ± 0.00 a | ND | ND | ND | 0.32 ± 0.01 b | 0.66 ± 0.03 c,d | 0.78 ± 0.03 e | 0.69 ± 0.03 d | 0.36 ± 0.01 b | 0.65 ± 0.03 c | 0.03 ± 0.00 a |
| stilbenoid | |||||||||||||
| P19 | Resveratrol | 2.25 ± 0.11 a | 2.22 ± 0.11 a | 2.27 ± 0.11 a | 2.22 ± 0.11 a | 2.23 ± 0.11 a | 2.25 ± 0.11 a | 2.23 ± 0.11 a | 2.22 ± 0.11 a | 2.26 ± 0.11 a | 2.23 ± 0.11 a | 2.23 ± 0.11 a | 2.23 ± 0.11 a |
Note: Different letters in the same column indicate statistically significant differences (p < 0.05). Values are the means of triplicate determination (n = 3) ± S.D; ND: not detected.
The phenolic acid contents varied among wines, consistent with previous studies [24]. Roussanne juice and wine had a high phenolic acid content (4.05 mg/L and 8.05 mg/L, respectively). Hydroxycinnamic acid was the main non-flavonoid phenolic compound in white wines, being primarily located in grape flesh [20,25] and increasing the possibility of browning, thus affecting the color of wine. The hydroxycinnamic acid content in Aranèle juice was the highest (1.85 mg/L), being 1.08–1.82 times higher than those of other wines.
Caffeic acid is easily oxidized, which leads to the browning of wine. It was also a precursor of volatile phenols [26]. Caffeic acid was detected in six kinds of grape juice, and its content had no significant difference. After fermentation, the caffeic acid content increased, up to 0.85 mg/L in Aranèle, accounting for 46.11% of the total content of hydroxycinnamic acid.
Regarding other phenols, such as resveratrol (trans-resveratrol), their content did not change significantly during fermentation. It has been reported that the resveratrol content in wines is largely influenced by grape variety, plant stress conditions, and winemaking practices [27].
3.5. Volatile Components
The volatiles of six grapes and wines were determined by HS-SPME-GC-MS, and 73 flavor substances were detected, including 24 esters, 13 higher alcohols, 8 fatty acids, 8 aldehydes, 15 terpenes, 2 ketones, and 3 others. Table 3 shows that esters made up the highest proportion of volatile compounds in wines, followed by higher alcohols, fatty acids, terpenes, and ketones. Among the six grape juice varieties, the total volatile component content in Viognier was the highest, while that in Italian Riesling was the lowest. After fermentation, the contents of total volatile components in Semillon wine (56,147.3 μg/L) were highest.
Esters have a tropical, fruity, and pleasant floral fragrance and are one of the most important odor-contributing compounds of wine [7]. There were no significant differences in the ester contents of six grape varieties (p < 0.05). After fermentation, the types of ester compounds were more varied in Viognier and Chardonnay wines, while the contents were highest in Semillon (44,791.8 μg/L) and Viognier (42,540.9 μg/L) wines, being far higher than in other wines. The high concentration of fruit esters may markedly enhance to the aromatic characteristics observed in the sensory profile. In this experiment, ethyl laurate, ethyl decanoate, and ethyl octanoate were the predominant ethyl esters in wines. These compounds provided a fruity aroma—a peanut, pineapple, and coconut aroma—with a sweet taste [28]. The maximum ethyl octanoate content in Semillon wine was 15,460.3 μg/L, which was 2.8 times higher than that of Aranèle (5509.7 μg/L). The ethyl decanoate content in Viognier wine was the highest (21,970.1 μg/L), which was 5.0 times higher than that of Italian Riesling (4392.1 μg/L). The ethyl 9-decenoate content was the highest in Italian Riesling wine (1793.7 μg/L), but this component was not detected in Aranèle wine. Wine with high isoamyl acetate content exuded a pleasant floral and banana fragrance [29], and its content in Semillon wine (4590.2 μg/L) was 4.4 times higher than that in Aranèle wine (1038.6 μg/L). Ethyl caproate was found in all wine samples, and there were no significant differences in content between wines. This component can provide wine with a rich fruity aroma, specifically a pear- and apple-like aroma [30,31].
Table 3.
The identification and quantitative results of volatile compounds in the six grape juices and wine varieties (μg/L).
| FNo | Volatile Compounds | RI | Grape Juice | Wine | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | Chardonnay | Aranèle | Roussanne | Viognier | Italian Riesling | Semillon | |||
| Esters | ||||||||||||||
| V01 | Isoamyl acetate | 1138 | ND | ND | ND | ND | ND | ND | 1564.6 ± 163.7 a,b | 1038.6 ± 44.7 a | 1445.4 ± 64.4 a,b | 1798.9 ± 352.3 b | 1158.0 ± 317.5 a | 4590.2 ± 71.6 c |
| V02 | Ethyl Hexanoate | 1245 | ND | ND | ND | ND | ND | ND | 839.9 ± 107.3 a | 913.3 ± 86.6 a | 756.1 ± 84.7 a | 920.5 ± 274.0 a | 837.0 ± 260.6 a | 3075.6 ± 89.1 b |
| V03 | Hexyl acetate | 1284 | ND | ND | ND | ND | ND | ND | 233.5 ± 39.2 a,b | 155.0 ± 9.6 a | 273.6 ± 28.7 b,c | 232.2 ± 71.4 a,b | 216.3 ± 65.4 a,b | 351.9 ± 14.5 c |
| V04 | Ethyl octanoate | 1445 | ND | ND | ND | ND | ND | ND | 5954.3 ± 591.0 a | 5509.6 ± 883.9 a | 6329.0 ± 128.9 a,b | 10,187.7 ± 3171.8 b | 6012.6 ± 634.7 a | 15,460.3 ± 765.0 c |
| V05 | Isopentyl hexanoate | 1466 | ND | ND | ND | ND | ND | ND | ND | ND | ND | 34.6 ± 9.7 a | ND | 57.3 ± 2.9 b |
| V06 | Propyl caprylate | 1527 | ND | ND | ND | ND | ND | ND | ND | ND | ND | 28.4 ± 14.2 a | ND | 18.2 ± 0.6 a |
| V07 | Ethyl nonanoate | 1544 | ND | ND | ND | ND | ND | ND | 37.2 ± 1.4 a | ND | 31.5 ± 1.3 a | 177.8 ± 95.9 b | ND | ND |
| V08 | Ethyl decanoate | 1645 | 0.6 ± 0.1 a,b | 0.9 ± 0.1 d | 0.7 ± 0.0 c | 0.5 ± 0.0 a | 0.7 ± 0.0 b,c | 0.6 ± 0.0 a,b | 14,613.5 ± 1109.8 b | 6582.9 ± 392.4 a | 12,542.4 ± 780.9 b | 21,970.1 ± 5509.0 c | 4392.0 ± 950.4 a | 15,720.0 ± 683.5 b |
| V09 | Isoamyl caprylate | 1665 | ND | ND | ND | ND | ND | ND | 402.9 ± 46.7 a | 93.4 ± 6.4 a | 248.1 ± 26.6 a | 1240.7 ± 467.9 b | 49.99 ± 9.73 a | 173.2 ± 11.0 a |
| V10 | Ethyl 9-decenoate | 1699 | ND | ND | ND | ND | ND | ND | 581.9 ± 57.4 b | ND | 95.2 ± 5.8 a | 272.4 ± 77.8 a,b | 1793.7 ± 475.4 c | 349.5 ± 29.9 a,b |
| V11 | N-Propyl decanoate | 1729 | ND | ND | ND | ND | ND | ND | 26.0 ± 3.1 a | ND | 6.0 ± 0.6 a | 73.66 ± 8.29 b | ND | 11.91 ± 1.11 a |
| V12 | Isobutyl decanoate | 1760 | ND | ND | ND | ND | ND | ND | 3.6 ± 0.1 a | ND | 26.6 ± 3.7 a | 63.5 ± 5.9 b | ND | ND |
| V13 | Phenethyl acetate | 1830 | ND | ND | ND | ND | ND | ND | 739.2 ± 52.9 c | 562.6 ± 17.4 b | 1081.4 ± 19.4 f | 823.1 ± 46.9 d | 452.2 ± 9.0 a | 905.3 ± 27.1 e |
| V14 | Ethyl laurate | 1848 | ND | 0.4 ± 0.0 a | 0.4 ± 0.0 a | 0.5 ± 0.2 a | 0.4 ± 0.0 a | 0.4 ± 0.0 a | 3491.2 ± 243.7 c | 2117.2 ± 191.8 b | 2814.7 ± 668.1 b,c | 2792.1 ± 113.8 b,c | 1047.6 ± 95.7 a | 3439.6 ± 44.9 c |
| V15 | Isopentyl decanoate | 1867 | ND | ND | ND | ND | ND | ND | 572.7 ± 76.5 b | 108.7 ± 14.3 a | 320.7 ± 61.1 a,b | 1301.1 ± 313.8 c | 50.1 ± 4.2 a | 136.6 ± 5.0 a |
| V16 | Ethyl myristate | 2054 | ND | ND | ND | ND | ND | ND | 101.0 ± 16.4 b | 72.8 ± 14.9 a,b | 48.3 ± 9.5 a | 90.9 ± 22.4 b | 41.7 ± 0.7 a | 52.0 ± 8.4 a |
| V17 | Ethyl (E)-2-decenoate | 2104 | ND | ND | ND | ND | ND | ND | 2.6 ± 0.1 a | ND | 3.1 ± 0.3 a | 19.1 ± 1.6 b | ND | ND |
| V18 | Ethyl pentadecanoate | 2156 | ND | ND | ND | ND | ND | ND | 16.3 ± 4.6 a | ND | ND | 17.6 ± 2.2 a | ND | ND |
| V19 | 2-Phenethyl hexanoate | 2183 | ND | ND | ND | ND | ND | ND | 20.0 ± 1.0 b | 4.0 ± 0.2 a | 17.6 ± 2.2 b | ND | 3.0 ± 0.5 a | ND |
| V20 | Ethyl palmita | 2259 | ND | ND | ND | ND | ND | ND | 510.5 ± 106.2 c | 215.2 ± 35.9 a | 314.6 ± 81.0 a,b,c | 452.6 ± 95.4 b,c | 201.8 ± 3.5 a | 292.6 ± 114.9 a,b |
| V21 | Ethyl 9-hexadecenoate | 2287 | ND | ND | ND | ND | ND | ND | 179.8 ± 20.0 a | ND | ND | ND | 312.5 ± 29.6 b | 153.4 ± 19.7 a |
| V22 | 2-Phenethyl octanoate | 2394 | ND | ND | ND | ND | ND | ND | ND | 2.8 ± 0.0 a | ND | 5.1 ± 0.4 c | ND | 3.7 ± 0.5 b |
| V23 | Ethyl stearate | 2464 | ND | ND | ND | ND | ND | ND | 20.1 ± 6.4 a,b | ND | 25.3 ± 1.2 b | 16.6 ± 1.7 a | ND | ND |
| V24 | Butyl isobutyl phthalate | 2724 | ND | ND | ND | ND | ND | ND | ND | ND | 27.6 ± 2.3 b | 21.2 ± 1.4 a | ND | ND |
| Higher alcohols | ||||||||||||||
| V25 | 1-Pentanol | 1219 | ND | ND | ND | ND | ND | ND | 2485.9 ± 20.4 b | 2651.4 ± 24.1 c | 2262.4 ± 12.5 a | 2361.3 ± 18.9 a,b | 2483.3 ± 2.8 b | 2277.0 ± 144.3 a |
| V26 | (Z)-2-Pentenol | 1331 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V27 | 1-Hexanol | 1362 | 56.3 ± 0.1 c | 38.6 ± 0.4 b | 38.2 ± 1.2 b | 60.7 ± 4.7 c | 22.8 ± 0.5 a | 56.6 ± 0.7 c | 57.5 ± 2.2 c | 60.0 ± 0.2 c | 73.6 ± 1.5 e | 44.2 ± 0.6 b | 64.5 ± 1.6 d | 22.0 ± 0.4 a |
| V28 | (3E)-Hexenol | 1394 | 0.5 ± 0.0 a | 2.8 ± 0.1 c | 5.2 ± 0.1 d | 0.4 ± 0.0 a | 1.7 ± 0.4 b | 2.3 ± 0.7 b,c | ND | ND | ND | ND | ND | ND |
| V29 | (Z)-2-Hexen-1-ol | 1416 | 19.4 ± 0.5 a | 18.0 ± 0.1 a | 42.3 ± 1.9 d | 24.6 ± 1.5 b | 18.8 ± 0.7 a | 33.4 ± 2.7 c | ND | ND | ND | ND | ND | ND |
| V30 | 1-Octen-3-ol | 1458 | 0.8 ± 0.0 a | 1.2 ± 0.0 a | 0.9 ± 0.0 a | 1.1 ± 0.0 a | 0.9 ± 0.0 a | 1.0 ± 0.5 a | ND | ND | ND | ND | ND | ND |
| V31 | 1-Heptanol | 1463 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | 2.8 ± 0.0 a | ND |
| V32 | 2-Ethylhexanol | 1497 | 0.9 ± 0.1 a,b | 0.8 ± 0.1 a | 1.0 ± 0.0 a,b | 0.8 ± 0.1 a | 1.2 ± 0.1 b | 1.6 ± 0.1 c | ND | ND | ND | ND | ND | 20.6 ± 1.2 a |
| V33 | 3-Ethyl-4-methylpentanol | 1517 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V34 | 1-Nonanol | 1667 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V35 | (E)-2-Nonen-1-ol | 1721 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V36 | Benzyl alcohol | 1889 | 0.4 ± 0.0 a | 2.7 ± 0.0 c | 0.7 ± 0.0 a | 2.4 ± 0.4 c | 1.5 ± 0.0 b | 1.6 ± 0.2 b | ND | ND | ND | ND | ND | ND |
| V37 | Phenethyl alcohol | 1924 | 3.9 ± 0.1 a | 7.5 ± 0.3 c | 6.8 ± 0.1 c | 5.0 ± 0.5 b | 5.8 ± 0.1 b | 6.8 ± 0.7 c | 1053.2 ± 14.3 a | 1807.2 ± 23.4 c | 1050.6 ± 49.7 a | 1038.1 ± 26.0 a | 1458.5 ± 35.1 b | 988.9 ± 46.1 a |
| Fatty acids | ||||||||||||||
| V38 | Hexanoic acid | 1857 | ND | ND | ND | ND | ND | ND | 413.2 ± 7.7 d | 390.4 ± 5.6 c,d | 275.8 ± 16.6 a | 380.0 ± 9.4 c | 326.8 ± 7.6 b | 375.4 ± 9.7 c |
| V39 | (E)-2-Hexenoic acid | 1979 | 9.3 ± 0.3 a,b | 5.2 ± 0.0 a | 8.4 ± 0.1 a,b | 10.1 ± 2.7 b | 7.7 ± 0.6 a,b | 7.3 ± 3.2 a,b | ND | ND | ND | ND | ND | ND |
| V40 | Octanoic acid | 2073 | ND | ND | ND | ND | ND | ND | 4854.4 ± 317.3 c | 4525.1 ± 118.1 bc | 3133.3 ± 99.6 a | 4439.7 ± 322.6 b,c | 4084.6 ± 147.4 b | 4549.4 ± 7.0 b,c |
| V41 | Nonanoic acid | 2180 | ND | ND | ND | ND | ND | ND | 17.4 ± 0.1 a | ND | 13.4 ± 3.0 a | 16.4 ± 6.6 a | 16.3 ± 1.3 a | ND |
| V42 | n-Decanoic acid | 2282 | ND | ND | ND | ND | ND | ND | 3490.8 ± 99.6 b | 3576.9 ± 303.6 b | 2214.5 ± 35.8 a | 2211.3 ± 272.5 a | 3136.8 ± 574.6 b | 2858.2 ± 176.4 a,b |
| V43 | Caproleic acid | 2345 | ND | ND | ND | ND | ND | ND | 47.5 ± 1.3 a | ND | ND | ND | 257.6 ± 41.0 b | ND |
| V44 | Lauric acid | 2495 | ND | ND | ND | ND | ND | ND | 106.2 ± 12.8 a,b | 146.5 ± 12.7 b,c | 66.3 ± 6.0 a | 74.6 ± 0. 2 a | 153.6 ± 39.6 c,d | 195.4 ± 1.4 d |
| V45 | Myristic acid | 2713 | ND | ND | ND | ND | ND | ND | 1.5 ± 0.0 a | 23.2 ± 2.8 b | ND | ND | 24.3 ± 1.3 b | 24.7 ± 2.3 b |
| Aldehydes | ||||||||||||||
| V46 | Hexanal | 1103 | 52.1 ± 0.5 c,d | 58.4 ± 1.4 d | 42.1 ± 2.0 b,c | 59.6 ± 1.1 d | 29.2 ± 0.2 a | 37.8 ± 10.6 a,b | ND | ND | ND | ND | ND | ND |
| V47 | (E)-2-Hexenal | 1234 | 157.0 ± 5.6 c | 112.1 ± 3.9 a,b | 97.0 ± 0.9 a | 131.0 ± 8.3 b,c | 89.8 ± 3.2 a | 140.3 ± 25.6 b,c | ND | ND | ND | ND | ND | ND |
| V48 | 1-Nonanal | 1406 | 0.9 ± 0.0 a | 0.7 ± 0.0 a | 3.6 ± 0.1 c | ND | ND | 2.1 ± 0.2 b | ND | ND | ND | ND | ND | ND |
| V49 | (E,E)-2,4-Heptadienal | 1508 | 1.3 ± 0.0 a | 1.0 ± 0.4 a | 0.8 ± 0.1 a | 1.1 ± 0.1 a | 1.4 ± 0.0 a | 1.6 ± 0.6 a | ND | ND | ND | ND | ND | ND |
| V50 | Benzaldehyde | 1539 | 19.9 ± 1.4 c | 18.1 ± 1.7 c | 10.2 ± 0.4 b | 5.1 ± 0.5 a | 5.8 ± 0.1 a | 11.6 ± 1.2 b | ND | ND | ND | ND | ND | ND |
| V51 | (E)-2-Nonenal | 1547 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V52 | Phenyl acetaldehyde | 1661 | 2.6 ± 0.0 a | 14.4 ± 0.8 c | 5.4 ± 0.3 b | 4.5 ± 0.7 a,b | 5.8 ± 0.5 b | 2.5 ± 1.5 a | ND | ND | ND | ND | ND | ND |
| V53 | Isoxylaldehyde | 1828 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| Terpenes | ||||||||||||||
| V54 | Citral | 1744 | ND | 0.3 ± 0.0 a | ND | 0.7 ± 0.0 b | ND | 0.9 ± 0.1 c | ND | ND | ND | ND | ND | ND |
| V55 | Myrcene | 1176 | ND | 1.6 ± 0.08 a | 1.7 ± 0.0 a | 1.7 ± 0.1 a | ND | 2.3 ± 0.3 b | ND | ND | ND | ND | ND | ND |
| V56 | (+)-Dipentene | 1211 | ND | 2.1 ± 0.1 a | 3.5 ± 0.3 c | 2.3 ± 1.0 a,b | ND | 2.4 ± 0.3 a,b | ND | ND | ND | ND | ND | ND |
| V57 | Ocimene | 1261 | ND | 1.3 ± 0.3 a | 2.3 ± 0.0 b | 2.0 ± 0.7 a,b | ND | 2.0 ± 0.2 a,b | ND | ND | ND | ND | ND | ND |
| V58 | Terpinolene | 1293 | ND | 2.2 ± 0.2 b | 5.6 ± 0.4 c | 2.6 ± 1.2 b | ND | 1.4 ± 0.8 a,b | ND | ND | ND | ND | ND | ND |
| V59 | Allocimene B | 1384 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V60 | p-Cymenene | 1450 | ND | 0.7 ± 0.0 a | 1.7 ± 0.1 b | ND | 0.7 ± 0.1 a | ND | ND | ND | ND | ND | ND | ND |
| V61 | Linalool | 1555 | 0.4 ± 0.0 a | 25.7 ± 1.6 b,c | 36.6 ± 2.0 c | 31.6 ± 16.8 b,c | 2.5 ± 0.0 a | 16.0 ± 8.0 a,b | ND | ND | 4.2 ± 0.6 a | ND | ND | ND |
| V62 | α-Ionene | 1565 | 0.4 ± 0.0 a | 0.8 ± 0.0 a | 10.3 ± 0.0 c | 0.9 ± 0.1 a | 5.2 ± 0.7 b | ND | ND | ND | 6.1 ± 1.1 a | ND | 7.2 ± 1.9 a | 18.2 ± 2.3 b |
| V63 | (E)-Caryophyllene | 1619 | ND | 0.3 ± 0.0 a | ND | ND | 0.4 ± 0.0 a | 2.2 ± 0.0 b | ND | ND | ND | ND | ND | ND |
| V64 | (−)-α-Terpineol | 1706 | ND | 7.8 ± 0.4 b,c | 10.8 ± 0.8 c | 7.9 ± 4.8 b,c | 1.3 ± 0.1 a | 4.2 ± 1.4 a,b | ND | ND | ND | ND | ND | ND |
| V65 | Citronellol | 1773 | ND | 1.3 ± 0.0 b | ND | ND | ND | 0.5 ± 0.0 a | ND | ND | ND | ND | ND | ND |
| V66 | Nerol | 1809 | ND | 0.5 ± 0.0 a | 0.4 ± 0.0 a | 0.6 ± 0.0 a | ND | 0.5 ± 0.0 a | ND | ND | ND | ND | ND | ND |
| V67 | β-Damascenone | 1832 | 4.3 ± 0.6 b | 7.5 ± 0.3 c | 11.3 ± 1.1 d | 1.2 ± 1.1 a | 23.2 ± 1.5 e | 4.6 ± 0.3 b | ND | ND | ND | ND | ND | ND |
| V68 | Geraniol | 1856 | 18.6 ± 0.9 b | 16.6 ± 0.7 b | 13.3 ± 0.3 a,b | 27.3 ± 5.2 c | 8.9 ± 0.1 a | ND | ND | ND | ND | ND | ND | ND |
| Ketones | ||||||||||||||
| V69 | 1,1,5,6-Tetramethylindan | 1433 | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | 3.7 ± 0.9 a | ND |
| V70 | Coumaran | 2409 | ND | ND | ND | ND | ND | ND | 82.6 ± 7.7 b | ND | 20.5 ± 1.4 a | 15.2 ± 0.1 a | ND | ND |
| Other substances | ||||||||||||||
| V71 | 4-Hydroxy-3-methoxystyrene | 2210 | ND | 0.2 ± 0.2 a | ND | ND | 0.4 ± 0.0 a | 0.4 ± 0.0 a | 52.8 ± 4.7 c | 34.1 ± 0.8 b | 52.0 ± 2.4 c | 49.9 ± 1.1 c | 36.8 ± 2.4 b | 25.6 ± 0.6 a |
| V72 | Spiroxide | 1509 | ND | 0.3 ± 0.0 a | 0.9 ± 0.1 b | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| V73 | Cadalene | 2236 | 0.4 ± 0.0 a | 0.4 ± 0.0 a | 0.6 ± 0.0 b | 0.6 ± 0.0 b | 0.4 ± 0.0 a | ND | ND | 13.9 ± 1.7 a | ND | ND | ND | ND |
Note: Different letters used in the same column indicate statistically significant differences (p < 0.05). Values are the means of triplicate determination (n = 3) ± S.D; ND: not detected.
Viognier juice contained the most varied alcohol compound. The content in Semillon juice was the highest, which was up to 106.7 μg/L. The concentrations of 1-hexanol and (Z)-2-hexen-1-ol were comparatively high. The 1-hexanol content in Viognier juice (60.8 μg/L) was 2.7 times higher than that in Italian Riesling (22.9 μg/L). The (Z)-2-hexen-1-ol content in Roussanne juice (42.2 μg/L) was 2.3 times higher than that in Aranèle (18.1 μg/L). These results were consistent with the findings of Li et al. [32]. Following fermentation, the total contents of alcohol compounds increased, especially phenethyl alcohol and pentanol, giving the wine a soft, pleasant, rose, and fusel oil aroma [33].
Terpenoids are secondary metabolites and their content is relatively low in grapes. They have an important influence on the aroma of wine due to their floral and fruity aromas [34]. Terpene contents were different in the six kinds of grape juices. Thirteen terpenes were detected in Aranèle juice; however, only four species were detected in Chardonnay juice. The total terpene content in Roussanne juice (97.2 μg/L) was 4.1 times higher than that in Chardonnay juice (23.9 μg/L). Both the content and species of terpenes obviously decreased after fermentation. Regarding terpenoids, linalool had a sweet and fresh floral and lemon fragrance. It was detected in all six grape juices, but only in Roussanne wine. The β-damascenone content in Italian Riesling juice (23.3 μg/L) was high, and it had a strong rose-like fragrance [28]. Geraniol had a mild and sweet rose flavor and bitter taste, which was detected in all grape juices except Semillon juice. At the end of fermentation, the contents and types of terpenoids decreased, which may be related to low-temperature fermentation. Previous studies showed that low-temperature fermentation reduced the formation of terpenoids but promoted the formation of esters [35]. This experiment further supports the previously expressed viewpoints.
Aldehydes are a large class of volatile compounds found in grapes, which can impart fruity and fresh plant aromas to wine [36]. Among the six types of grape juices, (E)-2-hexen-1-ol was present at a relatively high concentration, characterized by a strong aroma of fresh fruits and green leaves. The aldehyde content of Chardonnay juice (157.0 μg/L) was 1.8 times higher than that of Italian Riesling juice (89.9 μg/L). Following yeast fermentation, aldehyde content in wine decreased and could not be detected.
3.6. Principal Component Analysis (PCA) of White Wine
Principal component analysis was employed to statistically evaluate the data of organic acids, polyphenols, and aromatic compounds in six white wines, identifying the compounds that predominantly influence the quality of white wines. It also assessed the characteristics of grape samples and distinguished between grape varieties. The number of principal components was determined to be two, based on an eigenvalue larger than 1 and a cumulative variance contribution over 80%, with a cumulative contribution rate of 85.00% (43.37% and 41.63%, respectively; Figure 3A). The distribution results of the six wines are shown in the score chart (Figure 3B).
Figure 3.
Principal component analysis of chemical properties of six white wines. Note: (A) Factor loadings and (B) factor scores. Abbreviations: O02: tartaric acid; O04: malic acid; O08: butanedioic acid; P01: Gallic acid; P03: Gentisic acid; P10: Caffeic acid; P12: Ferulic Acid; P13: Rutin; P15: Quercetin; P16: Catechin; P18: L-Epicatechin; V02: Ethyl Hexanoate; V09: Isoamyl caprylate; V10: Ethyl 9-decenoate; V15: Isopentyl decanoate; V16: Ethyl myristate; V21: Ethyl 9-hexadecenoate; V27: 1-Hexanol; V44: Lauric acid; V13: Phenethyl acetate.
The PC1 scores of Semillon and Italian Riesling wines were positive. Ester compounds (ethyl 9-hexadecenoate, ethyl hexanoate, and ethyl 9-decenoate), caffeic acid, tartaric acid, quercetin, and succinic acid were present at higher concentrations, and they were closely associated with PC1. During loading variable analysis, we found a connection between PC1 and isopentyl alcohol decanoate, gallic acid, and gentisic acid. From the perspective of PC2, malic acid, tartaric acid, ferulic acid, gentisic acid, L-epicatechin, and ester substances (isoamyl caprylate and isopentyl decanoate) were positively correlated with Aranèle, Roussanne and Viognier wines.
Several studies showed that the flavanol pattern was mainly driven by genetic divergences among cultivars [8,9]. This study further demonstrated that catechin and epicatechin can serve as effective indicators for distinguishing white grape varieties. In addition, the main aroma components were different in the six white wines. Ethyl ester levels were higher in Semillon and Italian Riesling wines, but isoamyl ester levels were higher in Aranèle, Roussanne, and Viognier wines.
It should be noted that the grapes for this study were sourced from a single vineyard. While this provides controlled conditions for comparing cultivars, it may limit the generalizability of the results to other region. Future studies incorporating multiple vineyard locations would enhance the ecological validity of the findings.
3.7. Sensory Analysis of Wines
The radar chart (Figure 4) shows the average value of the significance level attributes of the six single varieties of wine. As shown via sensory analysis, there was no significant difference among the six white wines in terms of appearance. There were obvious differences in aroma and taste: Aranèle wine was fragrant with floral and peach aromas, sweet, smooth and clean in mouth, and lively in acidity. Semillon wine had a rich aroma, fresh floral fragrance, sweet and crisp mouth, and lively acidity. Italian Riesling wine had a strong peach aroma, sweet taste, and cheerful acidity. Viognier wine had an open sweet and honeysuckle fragrance, with a sweet taste and harmonious and fresh acidity. Roussanne wine had an outstanding vanilla aroma, a soft and delicate mouth, and a harmonious body. Chardonnay wine had a warm sweet and citrus aroma, and its mouth was mellow and clean. Overall, the sensory differences described align with the distinct phenolic compounds and aromatic profiles revealed among the cultivars.
Figure 4.
Sensory description analysis of six single varieties of wine.
4. Conclusions
We presented detailed insights into the metabolic components of six white grape juices and wines for the first time. More specifically, the phenolic profiles of berries and wines were analyzed using LC-MS, the organic acid content was analyzed via HPLC, and the volatile compound content was analyzed through HS-SPME-GC-MS.
Our findings indicated that there were obvious differences in the total sugar contents of the six kinds of grapes, with the Aranèle and Viognier grapes exhibiting the highest levels. The total tannin contents (TTCs) in the skins of Roussanne and Viognier were significantly higher than those of the other varieties. The total flavonoid content (TFo) and total flavan-3-ol content (TFa) in the skin were highest in Roussanne and lowest in Aranèle. Malic, tartaric, and succinic acids were the main organic acids found in wine. The total organic acid content of Roussanne wine was significantly higher than those of the other wines, followed by Aranèle and Italian Riesling wines. Six grape juices and wines were analyzed via LC-MS/MS, identifying 6 flavonoids, 12 phenolic acids, and 1 stilbene as the primary phenolic compounds. The concentrations of quercetin, proanthocyanidins, catechins, and protocatechuic acid in wine were higher, consistent with previous research findings. Hydroxycinnamic acid constituted the primary non-flavonoid phenolic compound in white wines, with the highest concentration found in Aranèle juice. A total of 73 flavor substances were detected, including esters, high alcohols, acids, aldehydes, terpenes, ketones, etc. In this experiment, ethyl laurate, ethyl decanoate, and ethyl octanoate were higher esters in wines. The content of terpenoids in wine decreased after fermentation, and there were obvious differences among the different varieties of wines. The results of PCA indicated that catechin, epicatechin, etc., can serve as effective indicators for distinguishing white grape varieties.
In conclusion, our study provided a comprehensive characterization of the white grape varieties and wines analyzed, and the organic acids (tartaric acid, succinic acid), flavonoids (phenolic acid and flavane 3 alcohol), and volatile compound (C6,10,14 acids ethyl ester, C8,10 acids isopentyl ester, etc.) contents were regarded as particularly important tools of variety differentiation. This intervention is anticipated to enhance wine quality through cultivar optimization in the Changli producing area, thereby elevating the prestige of both individual wineries and the broader regional wine industry. Moreover, comprehensive investigations should be conducted to optimize the impregnated fermentation time, fermentation temperature, and screening of native yeast to produce high-quality white wine. Further validation across multiple vineyards was recommended to confirm the broader applicability. It would also be beneficial to further evaluate their features.
Author Contributions
Conceptualization, H.M. and Y.C.; methodology, W.K. and Y.M.; software, Y.H. and W.K.; validation, L.Q. and Y.H.; formal analysis, Y.M. and W.K.; investigation, Y.H.; resources, Y.H. and Y.C.; data curation, Y.M.; writing—original draft preparation, Y.M., H.Z. and W.K.; writing—review and editing, Y.M., W.K. and L.Q.; supervision, W.K.; project administration, L.Q.; funding acquisition, H.M. and L.Q. All authors have read and agreed to the published version of the manuscript.
Institutional Review Board Statement
This study qualifies for ethics exemption under Article 32 of China’s Measures for Ethical Review of Life Sciences and Medical Research Involving Human Subjects (2023), which permits non-interventional, anonymized sensory research (e.g., taste evaluations) with no physical/psychological risks. It aligns with the Declaration of Helsinki (2013) and ICMJE Guidelines for Non-Interventional Research (2025), ensuring anonymized data and voluntary consent. Therefore, ethics approval waived under institutional policy.
Informed Consent Statement
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.
Conflicts of Interest
Authors Yubo Hua and Yanzhi Cui were employed by the company Longus Vineyard Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Funding Statement
This research was funded by the S&T Program of Hebei, China (Grant No. 20327001D), and the leading Talent Project of Science and Technology Innovation in Ningxia Hui Autonomous Region (Grant No. 2022GKLRLX07).
Footnotes
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.