Assessing the suitability of boiling in the boletus species: a multimodal analysis of texture, flavor, and volatile profiles

Abstract

Multi-dimensional characterization was conducted to assess post-boiling quality variations among five Boletus species, with the aim of identifying the most suitable variety for boiling. Texture profile analysis revealed that Suillus luteus (HLT) and Leccinum aurantiacum (HC) exhibited tender textures, Boletus edulis (MW) was soft, Leccinum holopus (BC) was crisp, and Boletus aereus (YSH) was firm. Taste activity value analysis indicated that umami amino acids contributed most to the flavor of BC, sweet amino acids predominated in HLT, and bitter amino acids shaped the taste profiles of MW, HC, and YSH. Volatile flavor compound analysis showed that HLT was characterized by mushroom-like and fruity aromas, BC by fruity and creamy notes, HC by chocolate and fatty flavors, and MW and YSH by mushroom-like, fatty, and fruity aromas. Overall, HLT was identified as the most suitable species for boiling. These findings provide a theoretical basis for the precise processing of Boletus mushrooms.

Highlights

• •Suillus luteus showed best boiling suitability with tender texture, unique flavor.
• •Texture and flavor changes of five Boletus species after boiling were clarified.
• •Findings offer guidance for precision processing of Boletus mushrooms.

1. Introduction

Boletus mushrooms are a group of wild fungi with significant edible and medicinal value. They are rich in bioactive compounds such as polysaccharides, polyphenols, flavonoids, and alkaloids, which exhibit various physiological activities, including antioxidants, antitumor, and immunomodulatory effects. In addition to their health benefits, Boletus mushrooms are highly prized by consumers worldwide for their pleasant texture and distinctive flavor. According to global statistics, approximately 400–500 species of Boletus mushrooms have been identified, of which more than 100 are considered edible. However, about 40 species contain trace levels of toxins that may pose safety risks if consumed without proper processing (Dong et al., 2023). Therefore, applying appropriate thermal processing methods to facilitate toxin degradation is essential to ensure food safety. Common thermal processing techniques for Boletus mushrooms include boiling, stir-frying, and deep-frying (Xun et al., 2020). Studies have shown that stir-frying may reduce the bioavailability of minerals, while deep-frying can induce protein crosslinking and aggregation, thereby decreasing protein digestibility and amino acid availability (Shao et al., 2024; Yang et al., 2023). In contrast, boiling has been shown to significantly enhance the digestibility and absorption of mushroom proteins. Owing to its high and uniform heating, boiling also effectively degrades residual toxins and is widely regarded as the most suitable thermal processing method for Boletus mushrooms.

In China, Yunnan Province is recognized as one of the most resource-rich regions for Boletus mushrooms, owing to its unique geographical features and diverse climatic conditions (Tan et al., 2022). Among the numerous species found in this region, five are particularly representative: Boletus edulis (MW), Leccinum holopus (BC), Leccinum aurantiacum (HC), Suillus luteus (HLT), and Boletus aereus (YSH). MW is characterized by a brown or yellowish-brown smooth cap and a reticulated stipe. It is rich in amino acids, polysaccharides, polyphenols, and flavonoids, and exhibits notable antioxidant, immunomodulatory, and digestive-promoting activities (Kaprasob et al., 2022; Tremble et al., 2023). BC has a pale yellow appearance and is abundant in proteins, vitamins, and essential minerals, which contribute to enhanced immunity, bone development, and nervous system function (Meng et al., 2021). HC features thick, reddish flesh and is particularly rich in umami compounds such as glutamic acid and 5′-nucleotides, resulting in a pronounced savory taste; however, it contains trace toxins and requires thorough heat treatment before safe consumption (Szymańska et al., 2020). HLT is yellow in color and contains abundant polysaccharides, flavonoids, and alkaloids, demonstrating potent antibacterial, anti-inflammatory, and antitumor activities. YSH, with its dark brown hue, is enriched with polyphenols and various minerals, showing strong anti-inflammatory potential and promising immunoregulatory effects. Due to their distinctive flavor profiles and rich nutritional composition, these five Boletus species are highly favored by local populations. However, their harvesting period is primarily restricted to June through September, with limited availability during the rest of the year, resulting in substantial fluctuations in annual supply. In addition, their short postharvest shelf life and stringent storage requirements have hindered systematic research and the development of related Boletus-based products.

In addition to nutritional composition and bioactivity, sensory attributes are critical indicators for evaluating the overall quality of Boletus mushrooms. Among these, texture, taste, and flavor are the primary assessment parameters, with flavor playing a particularly decisive role in shaping consumer acceptance. Flavor not only defines the unique sensory characteristics of Boletus mushrooms but also serves as an important indicator of freshness. Numerous studies have demonstrated that drying processes significantly influence the flavor profile of Boletus species. For instance, during drying, MW produces a variety of Maillard reaction products (MRPs), including sulfur-containing compounds, pyrazines, pyrimidines, thiophenes, pyrroles, pyrans, and furans. These volatile compounds (VOCs) collectively contribute to characteristic nutty, roasted, and caramel-like notes (Zheng et al., 2024). Further analysis using gas chromatography–mass spectrometry (GC–MS) has revealed that both hot air drying and vacuum freeze-drying can markedly increase the content of 1-octen-3-ol in MW, a key compound responsible for its distinctive mushroom-like aroma (Zheng et al., 2023). Although existing research has extensively explored the impact of drying on the aroma profile of Boletus mushrooms, most studies have focused primarily on MW, resulting in limited diversity in the target species. In contrast, little systematic or comparative investigation has been conducted on differences in texture and flavor among various Boletus species subjected to boiling a common thermal processing method. Therefore, further research is urgently needed to expand the current understanding of how boiling affects the sensory qualities of different Boletus mushrooms.

To address this research gap, the present study focused on five representative Boletus species from Yunnan Province MW, BC, HC, HLT, and YSH. A series of advanced analytical techniques were employed, including scanning electron microscopy (SEM), texture profile analysis (TPA), low-field nuclear magnetic resonance (LF-NMR), amino acid profiling, electronic nose (E-nose), electronic tongue (E-tongue), headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (HS-SPME-GC × GC-TOF-MS), and headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS). These tools were used to systematically evaluate the textural properties, taste profiles, and flavor differences of the five species after boiling treatment, with the aim of identifying the most suitable Boletus variety for boiling-based processing. The findings provide comprehensive and systematic data to support the quality assessment of different Boletus species, while also laying a solid theoretical foundation for precision processing and future industrial applications.

2. Materials and methods

2.1. Materials and reagents

MW, BC, HC, HLT, and YSH were cultivated in Chuxiong County, Yunnan Province, China. The external conditions, including growth duration, light, temperature, and humidity, were maintained consistently throughout the experiment to ensure uniformity in the environmental factors. Analytical-grade glucose, copper sulfate, potassium sulfate, sulfuric acid, and sodium hydroxide, used in the experimental processes, were sourced from Shanghai Yuanye Biotechnology Co., Ltd.

2.2. Sample preparation

Five distinct species of Boletus mushrooms, selected for their consistent size, were thoroughly washed, cut into uniform pieces, and subjected to boiling in distilled water at a ratio of 1:10 (m/m) for 20 min. Following the boiling process, the samples were air-dried and stored for subsequent analysis.

2.3. Analysis of apparent morphology

The apparent morphology of the five distinct Boletus mushroom species, post-boiling, was analyzed using scanning electron microscopy (SEM, SU8010, Hitachi, Tokyo, Japan). The stipes of the Boletus mushrooms, sourced from the same region, were affixed to conductive adhesive and subsequently sputter-coated with gold for 45 s at 10 mA using a sputter coater (Ultim Max 65, Oxford Instruments, Abingdon, UK). The morphological characteristics of the samples were then captured at an acceleration voltage of 3 kV using the SE2 secondary electron detector on the SEM.

2.4. Texture analysis

The stipes of Boletus mushrooms were cut into uniformly thick pieces, and their texture was analyzed using a texture analyzer (TA-XT Plus, Texture Technologies, Hamilton, MA, USA). The testing conditions were as follows: the P/36R probe was selected, with pre-test, test, and post-test speeds set at 10.0 mm/s, 2.0 mm/s, and 10.0 mm/s, respectively. The deformation was set to 40 %, with a test interval of 2 s and a trigger force of 10 N. The measured parameters included hardness, elasticity, cohesiveness, viscosity, chewiness, and adhesiveness. For shear force testing, the HDP-BS probe was selected, with pre-test, test, and post-test speeds set at 10.0 mm/s, 2.0 mm/s, and 10.0 mm/s, respectively. The displacement was set to 6 mm, and the trigger force was 10 N.

2.5. LF-NMR analysis

LF-NMR relaxation times were measured using a nuclear magnetic resonance analyzer (NMI20–015 V-I, Suzhou Niumag Analytical Instrument Corporation, Suzhou, China). The Boletus mushrooms were placed in a PTFE tube with a diameter of 25 mm. The magnetic field strength was maintained at 0.5 T, the temperature was set at 32 °C, and the operating frequency was set to 23.0 MHz. The relevant parameters were as follows: wait time (TW) of 3000 ms, echo time (TE) of 1.0 ms, number of echoes (NECH) set to 10,000, and the number of scans (NS) was set to 8.

Transverse relaxation time (T2) is a critical parameter for describing the dynamic behavior of water molecules, as it is generally related to their mobility. Typically, a higher T2 value indicates better mobility of water molecules within the food matrix, suggesting less binding of water.

2.6. Amino acid analysis

Amino acid content in Boletus mushrooms was quantified using liquid chromatography-mass spectrometry (LC-MS). The Taste Activity Value (TAV), defined as the ratio of the amino acid content to its threshold value, was utilized to assess the contribution of amino acids to the overall flavor profile. A higher TAV indicates a more significant contribution of the amino acid to the flavor of the food, highlighting its role in taste enhancement.

2.7. E-nose and E-tongue analysis

The odor characteristics of Boletus mushroom samples were analyzed using a portable PEN 3 e-nose (AIRSENSE, Schwerin, Germany), which is equipped with ten metal sensors: W1C (aromatic compounds), W5S (nitrogen oxides), W3C (ammonia, aromatic compounds), W6S (hydrides), W5C (alkanes, aromatic compounds), W1S (methane), W1W (sulphides and terpenes), W2S (alcohols, aldehydes, and ketones), W2W (aromatic components and organic sulfides), and W3S (long-chain alkanes). Specifically, 10 g of Boletus mushrooms were chopped, placed in a 100 mL beaker, sealed with plastic wrap, and allowed to stand at room temperature for 1 h before testing. The testing parameters were configured as follows: sensor cleaning time of 80 s, sensor calibration time of 5 s, sample detection time of 80 s, and sample flow rate of 400 mL/min.

The taste characteristics of Boletus mushrooms were analyzed using a taste analysis system (TS-5000Z, Insent, Atsugi-Shi, Japan). Six sensors were employed for the evaluation: AAE (umami), CT0 (salty), CA0 (sour), C00 (bitter), AE1 (astringent), and GL1 (sweet).

2.8. HS-SPME-GC × GC-TOF-MS analysis

The headspace solid-phase microextraction (HS-SPME) method employed in this study was based on a previous report with some modifications (Zou et al., 2023). A 50/30 μm DVB/CAR/PDMS fiber was utilized in a manual headspace sampling system. A 0.5 g sample, spiked with 10 μL of the internal standards mixture (2-Octanol: 10 mg/L), was placed in a 20 mL headspace vial, where it was pre-equilibrated at 60 °C for 10 min. The SPME fiber was then immediately inserted into the GC-GC-TOF-MS inlet for thermal desorption at 250 °C for 5 min. The samples prepared by HS-SPME were directly analyzed for volatile organic compounds (VOCs) using GC × GC-TOF-MS. The GC × GC-TOF-MS system consisted of an Agilent 8890 A gas chromatograph (Agilent Technologies, Palo Alto, CA, USA), a cold-jet modulator, and a time-of-flight mass spectrometer (LECO, St. Joseph, MI, USA). A DB-Heavy Wax column (30 m × 250 μm × 0.5 μm, Agilent Technologies, Palo Alto, CA, USA) was employed. Helium (99.999 %) served as the carrier gas, at a flow rate of 1 mL/min. The initial temperature was maintained at 50 °C for 2 min, after which it was increased to 240 °C at a rate of 5 °C/min and held for 5 min. The ion source temperature was set at 250 °C, with the ionization potential of the mass spectrometer set at 70 eV. Spectra were collected over a mass range of 35–550 m/z, with an acquisition rate of 10 spectra/s.

The Relative Odor Activity Value (ROAV) was used to evaluate the contribution of individual volatile compounds to the overall flavor of the sample. A higher ROAV indicates a greater contribution to the overall flavor. The ROAV is calculated as follows: ROAVi = 100 × (OAVi / OAVmax), where OAVmax is the highest odor activity value (OAV) among the volatile compounds, and OAVi is the OAV of a specific volatile compound. The OAV is calculated as: OAV = Ci / OTi, where Ci is the concentration of the volatile compound, and OTi is the threshold concentration of flavor compounds in water (Feng et al., 2024).

2.9. HS-GC-IMS analysis

The method of headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) employed in this study was based on a previous report with modifications (Zou et al., 2023). The aroma characteristics of five distinct types of Boletus mushrooms were analyzed using gas chromatography (GC; Agilent 490, Palo Alto, California, USA) coupled with ion mobility spectrometry (IMS; FlavourSpec®, Dortmund, Germany). A 1 g sample of Boletus mushroom was accurately weighed, transferred into a 20 mL headspace vial, and incubated at 60 °C for 20 min. Each sample was analyzed in triplicate. Subsequently, 500 μL of the sample was automatically injected using a preheated syringe (85 °C, splitless mode) and separated on an MXT-5 capillary column (15 m × 0.53 mm internal diameter). The column temperature was maintained at 60 °C, with high-purity nitrogen (purity ≥99.999 %) as the carrier gas. The gas flow rate was programmed as follows: an initial flow rate of 2 mL/min was held for 2 min, followed by a linear increase to 10 mL/min over 8 min.

In the IMS ionization chamber, analytes were ionized in positive ion mode using a 3H ionization source. The ionized analytes were introduced into a 53 mm drift tube operated at a constant voltage (0.5 kV) and temperature (45 °C). High-purity nitrogen (≥ 99.99 %) was used as the IMS drift gas at a flow rate of 75 mL/min. Each spectrum was reported as an average of 12 scans. The retention indices (RIs) of the VOCs were determined using C4-C9 n-ketones as external standards. Qualitative analysis of VOCs was performed by matching drift times and RIs to those in the GC-IMS library database. The peak intensities in HS-GC-IMS were utilized for the relative quantification of the VOCs.

2.10. Statistical analysis

One-way analysis of variance (ANOVA) followed by Tukey's multiple comparisons test was employed for statistical analysis. Graphical representations were generated using Origin 2021 (OriginLab, MA, USA). Statistical significance was established at a threshold of p < 0.05.

3. Results and discussion

3.1. Apparent morphology analysis

The surface morphology of the stipes from five distinct Boletus mushroom species was examined at magnifications of 150× (upper) and 200× (lower) (Fig. 1). The analysis revealed that MW exhibited fewer surface pores, but the pores present were larger and arranged in a regular pattern of hyphae. In contrast, BC, HC, HLT, and YSH did not display significant differences in their morphological characteristics. The surfaces of these species were densely populated with numerous small pores, forming a honeycomb-like structure, which was highly comparable to the microstructure of shiitake mushrooms (Liu et al., 2022). Specifically, BC exhibited a loose surface morphology, suggesting enhanced elasticity, while HC displayed a smooth surface with neatly arranged hyphae. HLT demonstrated notable variations in pore sizes, whereas YSH presented a fibrous network structure, indicative of a more compact fiber organization. This structure may contribute to its enhanced water-holding capacity.

Fig. 1.

Scanning electron micrographs of five Boletus mushroom species. The top row presents the apparent morphology at ×150 magnification, while the bottom row depicts the apparent morphology at ×200 magnification.

3.2. Texture analysis

Texture is a crucial factor in evaluating the sensory quality of Boletus mushrooms. Hardness, a key texture parameter, plays a significant role in determining the sensory experience. Higher hardness values typically correspond to a denser tissue structure, increased chewiness, and reduced tenderness (Yao et al., 2023). Additionally, shear force serves as another vital indicator of tenderness; higher shear force values indicate firmer flesh and lower tenderness (Ketnawa & Rawdkuen, 2023). Elasticity, which refers to the ability of a food item to return to its original shape after deformation, directly influences the sensory properties. Foods with higher elasticity tend to enhance the overall sensory experience. Cohesiveness, which reflects the ability of food to maintain its structural integrity during chewing, is also an important determinant of texture. Higher cohesiveness values suggest a denser tissue structure and stronger water-holding capacity. Adhesiveness, closely related to polysaccharides and other colloidal substances, indicates the texture's elasticity at higher levels and a crisp, refreshing texture at lower levels (Luo et al., 2021).

As demonstrated in Table 1, YSH exhibited significantly higher values for hardness, cohesiveness, adhesiveness, chewiness, and shear force compared to the other four varieties. This suggests a denser tissue structure, stronger water-holding capacity, and lower tenderness, which aligns with the fibrous network structure observed in YSH. MW exhibited moderate hardness, high elasticity, and lower cohesiveness, chewiness, and shear force, reflecting a looser tissue structure and a soft, easy-to-chew texture. BC displayed the highest elasticity among the five varieties but lower cohesiveness, adhesiveness, and shear force, indicating a looser tissue structure and a crisp texture, which is consistent with the SEM observations. HC and HLT demonstrated highly similar and generally lower values for hardness, chewiness, adhesiveness, and shear force, indicating comparable tissue structures and textural properties, characterized by tenderness and ease of chewing.

Table 1.

Texture characteristics of boletus mushrooms.

Sample	Hardness(N)	Springiness(%)	Cohesiveness	Gumminess(N)	Chewiness(N)	Adhesiveness(N.s)	Shear force(N)
MW	5821.56 ± 53.39c	0.95 ± 0.00ab	0.69 ± 0.01c	3702.71 ± 316.85b	2716.53 ± 53.41c	42.72 ± 2.32d	2177.51 ± 176.22c
BC	10,641.95 ± 567.92b	0.96 ± 0.00a	0.70 ± 0.01c	1424.78 ± 81.66c	4559.34 ± 258.06b	25.23 ± 2.40b	4074.06 ± 28.46b
HC	3605.25 ± 271.76e	0.94 ± 0.00bc	0.77 ± 0.01ab	3293.55 ± 59.40b	2971.21 ± 17.55c	22.03 ± 0.80a	1710.91 ± 22.00d
HLT	4387.70 ± 124.11d	0.94 ± 0.01bc	0.74 ± 0.02b	3302.83 ± 75.06b	2772.92 ± 144.89c	28.66 ± 0.42c	2219.19 ± 91.34c
YSH	17,582.68 ± 318.49a	0.93 ± 0.02c	0.78 ± 0.01a	7477.61 ± 366.06a	5659.20 ± 382.71a	19.70 ± 0.41a	4393.60 ± 107.24a

Different letters attached to the values within the same column indicate the significantly different at p < 0.05 level.

The TPA revealed significant differences in the texture properties among the five distinct types of Boletus mushrooms. HLT and HC exhibited tender textures, MW was soft, BC was crisp, and YSH was firm.

3.3. Moisture state distribution analysis

According to literature reports, water in mushrooms is distributed across various subcellular regions, including the cell wall, cytoplasm, and vacuoles, each exhibiting distinct relaxation times. Based on these differences in relaxation times, water can be categorized into three types: bound water (0.1–10 ms), tightly associated with the cell wall and exhibiting limited mobility; immobilized water (10–100 ms), located in the cytoplasm and less mobile; and free water (100–10,000 ms), primarily found in vacuoles and intercellular spaces, displaying the highest mobility . Free water plays a crucial role in enzymatic reactions and fungal growth. Using peak area normalization, we quantified the distribution of these water states in five distinct types of Boletus mushrooms (Fig. 2a). As shown in Fig. 2b, free water accounted for the highest proportion (> 60 %) in all samples, consistent with previous studies demonstrating that free water is the predominant form in fresh mushrooms (Wang et al., 2022). Specifically, YSH exhibited the highest proportions of bound water (0.04 %) and immobilized water (32.49 %), with the lowest proportion of free water (67.47 %). MW and BC contained no detectable bound water, with immobilized water proportions of 15.23 % and 14.89 %, respectively, and the highest proportions of free water (84.77 % and 85.11 %, respectively). HC and HLT showed similar water states, with bound water proportions of 0.01 %, immobilized water proportions of 23.56 % and 28.73 %, and free water proportions of 76.43 % and 71.26 %, respectively. These results demonstrate significant differences in water distribution among the five Boletus species.

Fig. 2.

Moisture state distribution and amino acid analysis of five Boletus mushroom species (a) T₂ relaxation curve; (b) stacked moisture distribution plot; (c) heatmap of correlations between water components and texture; (d) clustering heatmap of amino acids.

Water state is a critical factor affecting food texture. Studies have demonstrated that water state is closely linked to the textural properties of meat (Wei et al., 2024). For example, research has found that braised pork with a higher proportion of immobilized water and a lower proportion of free water exhibited a more tender texture (Xu et al., 2023). However, the effect of water state on the texture of mushroom-based foods remains unclear. Therefore, this study further analyzed the correlation between water composition and textural properties in Boletus using Pearson correlation coefficients. As shown in Fig. 2c, bound water was positively correlated with hardness, cohesiveness, gumminess, chewiness, and shear force, but negatively correlated with springiness. Immobilized water was positively correlated with cohesiveness, gumminess, and chewiness, but negatively correlated with springiness. Free water was positively correlated with springiness, but negatively correlated with cohesiveness, gumminess, and chewiness. The correlation results indicated that water composition significantly influences the textural properties of Boletus, although this relationship differs significantly from that in meat. Specifically, MW and BC samples, which had higher proportions of free water, lower proportions of immobilized water, and no detectable bound water, exhibited looser tissue structures, poorer water retention, and more tender textures. HC and HLT samples, which had similar and relatively high proportions of bound water, immobilized water, and free water, displayed higher springiness and better chewiness. YSH samples, which had the highest proportions of bound water and immobilized water and the lowest proportion of free water, exhibited denser tissue structures, better water retention, but harder textures and poorer tenderness.

It has been concluded that a higher proportion of free water and lower proportions of bound and immobilized water lead to a more tender texture, while the opposite results in a harder texture and reduced tenderness.

3.4. Amino acid analysis

The flavor characteristics of edible mushrooms are primarily determined by the synergistic effects of non-VOCs and VOCs. Amino acids, as key non-volatile taste substances, undergo conversion into α-keto acids through deamination, followed by decarboxylation to generate aldehydes. These aldehydes can further degrade or oxidize into alcohols, acids, and other compounds, thereby participating in the biosynthesis of various flavor components. Based on their taste characteristics, amino acids can be classified into four categories: umami, sweet, bitter, and tasteless. Among these, umami and sweet amino acids play a dominant role in flavor formation, while bitter and tasteless amino acids exhibit significant flavor-enhancing effects (Zhuravleva & Sherin, 2021).

In this study, a total of 20 amino acids were identified from five distinct types of Boletus mushrooms, including 3 umami amino acids, 5 sweet amino acids, 9 bitter amino acids, and 3 tasteless amino acids. As shown in Table 2, significant differences were observed in the composition and content of amino acids among the different species. HLT exhibited the highest total amino acid content (3392.51 μg/g), with its umami amino acids (663.2 μg/g) and sweet amino acids (1412.9 μg/g) also being higher than those of other species. In contrast, HC had the highest content of bitter amino acids (743.55 μg/g), while YSH showed the highest content of tasteless amino acids (888.08 μg/g).

Table 2.

Amino acid content and TAV of boletus mushrooms.

NO	Amino Acids	Threshold (mg/g)	Concentrations(ug/g)					TAV values
	Umami Taste(3)		MW	BC	HC	HLT	YSH	MW	BC	HC	HLT	YSH
1	Thr	1.5	116.34 ± 2.34a	32.44 ± 1.07d	103.66 ± 1.84b	105.20 ± 0.05b	77.10 ± 1.93c	0.08	0.02	0.07	0.07	0.05
2	Asp	1	126.10 ± 2.93b	105.42 ± 2.54c	0.00 ± 0.00e	416.87 ± 6.65a	85.58 ± 0.52d	0.13	0.11	0.00	0.42	0.09
3	Glu	0.3	200.41 ± 2.44b	141.05 ± 4.93c	244.06 ± 4.51a	141.13 ± 0.46c	125.61 ± 2.12d	0.67	0.47	0.81	0.47	0.42
	Total		442.85	278.91	347.72	663.2	288.29	0.87	0.60	0.88	0.96	0.56
	Sweet Taste(5)
4	Gly	2.6	118.86 ± 2.57c	48.48 ± 0.86d	24.87 ± 1.26e	537.91 ± 9.11a	317.75 ± 12.18b	0.05	0.02	0.01	0.21	0.12
5	Ala	1.3	275.34 ± 0.58c	136.81 ± 3.16e	314.81 ± 8.75b	405.13 ± 4.67a	217.16 ± 6.78d	0.21	0.11	0.24	0.31	0.17
6	Ser	0.6	233.75 ± 0.63b	70.54 ± 1.50e	83.18 ± 2.34d	318.57 ± 4.34a	112.41 ± 2.52c	0.39	0.12	0.14	0.53	0.19
7	Pro	3	27.51 ± 0.32c	13.79 ± 0.39e	41.56 ± 0.12b	50.50 ± 1.03a	21.30 ± 0.64d	0.01	0.00	0.01	0.02	0.01
8	Asn	1	75.55 ± 1.09b	70.43 ± 2.09c	99.02 ± 2.35a	100.79 ± 1.17a	61.65 ± 2.08d	0.08	0.07	0.10	0.10	0.06
	Total		731.01	340.05	563.44	1412.9	730.27	0.73	0.32	0.50	1.17	0.55
	Bitter Taste(9)
9	Val	0.4	73.01 ± 1.16c	27.56 ± 0.65e	83.78 ± 2.77a	77.42 ± 0.78b	54.99 ± 1.26d	0.18	0.07	0.21	0.19	0.14
10	Ile	0.9	32.07 ± 0.52b	17.29 ± 0.21d	71.92 ± 1.13a	29.56 ± 0.19c	30.72 ± 0.93bc	0.04	0.02	0.08	0.03	0.03
11	Leu	1.9	74.03 ± 0.44a	29.24 ± 0.69e	32.56 ± 0.46d	60.16 ± 0.87c	64.59 ± 1.33b	0.04	0.02	0.02	0.03	0.03
12	Met	0.3	152.56 ± 0.25a	5.20 ± 0.02d	11.04 ± 0.40b	6.53 ± 0.17c	4.12 ± 0.14e	0.51	0.02	0.04	0.02	0.01
13	His	0.2	45.53 ± 1.13b	12.97 ± 0.29e	41.04 ± 1.52c	56.10 ± 0.43a	30.74 ± 1.00d	0.23	0.06	0.21	0.28	0.15
14	Phe	0.9	67.52 ± 0.63c	31.52 ± 0.82e	78.72 ± 1.28b	92.13 ± 1.19a	56.34 ± 1.11d	0.08	0.04	0.09	0.10	0.06
15	Arg	0.5	68.96 ± 1.77b	9.79 ± 0.21e	123.14 ± 3.60a	33.44 ± 0.43d	53.72 ± 1.68c	0.14	0.02	0.25	0.07	0.11
16	Tyr	0.9	166.10 ± 3.64c	95.38 ± 0.55e	288.50 ± 7.29b	313.90 ± 0.62a	158.31 ± 2.38d	0.18	0.11	0.32	0.35	0.18
17	Trp	0.9	38.95 ± 0.46a	8.81 ± 0.13d	12.85 ± 0.44c	24.59 ± 0.15b	5.35 ± 0.21e	0.04	0.01	0.01	0.03	0.01
	Total		718.73	237.76	743.55	693.83	458.88	1.43	0.36	1.22	1.11	0.72
	Tasteless(3)
18	Orn	nd	141.19 ± 2.19a	101.54 ± 3.38d	135.04 ± 6.05ab	133.21 ± 3.36b	121.79 ± 2.44c	nd	nd	nd	nd	nd
19	Gln	3	434.22 ± 8.17c	198.79 ± 8.00d	467.25 ± 5.25b	441.86 ± 4.44bc	718.21 ± 27.87a	0.14	0.07	0.16	0.15	0.24
20	Lys	0.5	77.90 ± 1.06b	17.51 ± 0.44d	88.36 ± 4.05a	47.51 ± 1.25c	48.08 ± 0.88c	0.16	0.04	0.18	0.10	0.10
	Total		653.31	317.84	690.65	622.58	888.08	0.30	0.10	0.33	0.24	0.34

Different letters attached to the values within the same column indicate the significantly different at p < 0.05 level.

To further elucidate the differences in amino acid composition, a cluster heatmap containing 20 amino acids was constructed (Fig. 2d). The results revealed that MW was dominated by bitter-related amino acids, with methionine (Met) and tryptophan (Trp) being the most abundant. Met is known to impart a cooked potato-like flavor and can be converted into 3-methylthiopropionaldehyde via the Ehrlich pathway, contributing to the characteristic flavors of garlic, onion, and other foods. BC and HC were primarily characterized by aspartic acid (Asp) and glutamic acid (Glu), respectively, which, in synergy with inosine monophosphate and guanosine monophosphate, significantly enhance the umami characteristics of mushrooms (Roland et al., 2024). HLT, on the other hand, was dominated by sweet amino acids, with serine (Ser), glycine (Gly), asparagine (Asn), proline (Pro), and alanine (Ala) being the major contributors. Additionally, glycine was also the predominant amino acid in YSH, imparting a unique sweet flavor (Patil et al., 2024).

The contribution of amino acids to the taste characteristics of Boletus mushrooms was further evaluated using the Taste Activity Value (TAV) (Table 2). The results showed that bitter amino acids had the highest TAV in MW, HC, and YSH (1.43, 1.22, and 0.72, respectively), indicating that bitter amino acids contribute more significantly to the taste of these three Boletus species. In contrast, BC exhibited the highest TAV for umami amino acids (0.60), while HLT showed the highest TAV for sweet amino acids (1.17), suggesting that umami and sweet amino acids are the dominant taste contributors in BC and HLT, respectively. These results demonstrate that the TAV analysis is highly consistent with the amino acid content and cluster heatmap data, collectively indicating that BC and HLT exhibit superior taste characteristics after boiling.

3.5. E-nose and E-tongue analysis

This study investigated the aroma and taste characteristics of five Boletus species using E-nose and E-tongue technologies. As efficient analytical tools, the E-nose and E-tongue can rapidly characterize the overall volatile odor profiles of samples. The radar chart of the E-nose (Fig. 3a) indicated that the five Boletus species exhibited high response values on the W1S, W1W, and W2W sensors, suggesting that sulfides, aromatic compounds, and terpenoids are the primary aroma components. Among these, HC exhibited significantly higher response values on these three sensors compared to the other four species, indicating that these components are key to HC's distinctive aroma characteristics. Studies have shown that sulfides are also important contributors to the aroma of shiitake mushrooms (Hou et al., 2021). Additionally, aromatic compounds in edible fungi primarily exist in the form of alcohols, aldehydes, ketones, and ester derivatives, all of which are critical to the characteristic aroma of mushrooms (Li et al., 2019). Terpenoids, widely distributed in nature, typically exhibit floral and fruity aromas. Principal component analysis (PCA) results (Fig. 3b) revealed that the first principal component (PC1) and the second principal component (PC2) accounted for 68.6 % and 17.8 % of the variance, respectively, with a cumulative contribution rate of 86.4 %. This indicates that the E-nose data effectively reflected the overall aroma characteristics of the five Boletus species. HC was primarily distributed in the first and fourth quadrants of the PC1 axis, correlating with the W1S, W2W, W2S, W1W, and W5S sensors. The other four species (MW, BC, HLT, and YSH) were concentrated in the first, second, and fourth quadrants of the PC1 axis, correlating with the W3S, W6S, W1C, W3C, and W5C sensors, indicating the presence of additional alkanes and hydrocarbons in these species.

Fig. 3.

The flavor and taste profiles of Boletus mushrooms were comprehensively analyzed using e-nose and e-tongue. (a) Radar plot of the E-nose; (b) PCA plot of the E-nose; (c) Radar plot of the E-tongue; (d) PCA plot of the E-tongue.

The E-tongue radar chart (Fig. 3c) demonstrated that the sweet, umami, and bitter sensors exhibited high signal levels across all five Boletus species, suggesting that sweetness, umami, and bitterness are the primary taste characteristics. PCA analysis of the E-tongue data (Fig. 3d) revealed that PC1 and PC2 accounted for 54.4 % and 26.2 % of the variance, respectively, with a cumulative contribution rate of 80.6 %, confirming that the E-tongue data effectively captured the flavor profiles of the five species. Specifically, MW was primarily located in the third quadrant of the PC1 axis, exhibiting a sweet taste; BC was concentrated in the second quadrant, indicating a salty taste; HLT was predominantly located in the first quadrant, showing a bitter taste; and HC and YSH were concentrated in the fourth quadrant, exhibiting a sour taste.

The E-nose results indicated that sulfides, aromatic compounds, and terpenoids are the primary aroma components in the five Boletus species, with HC's aroma characteristics being most significantly influenced by these components. Additionally, MW, BC, HLT, and YSH contained higher levels of alkanes and hydrocarbons. The E-tongue results revealed distinct taste differences among the species: MW was noted for its pronounced sweetness, BC for its saltiness, HLT for its bitterness, and HC and YSH for their sourness. The combined analysis of the E-nose and E-tongue provided preliminary insights into the aroma and taste characteristics of the five Boletus species, offering a foundation for further research. To further elucidate their flavor differences, subsequent studies will incorporate HS-SPME-GC × GC-TOF-MS and HS-GC-IMS for a more in-depth analysis.

3.6. HS-SPME-GC × GC-TOF-MS analysis

This study employed headspace solid-phase microextraction (HS-SPME) coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF-MS) to evaluate the flavor differences among five distinct types of Boletus mushrooms (MW, BC, HC, HLT, and YSH) after boiling treatment. A total of 122 volatile organic compounds (VOCs) were identified from the five species, which were categorized into 13 groups: 23 aldehydes, 22 alkanes, 17 ketones, 17 alcohols, 13 benzenes, 8 esters, 6 heterocyclic compounds, 5 alkenes, 3 acids, 3 amines, 2 terpenes, 2 phenols, and 1 ether (Fig. 4a). Further analysis of the VOCs content (Fig. 4b) revealed that alcohols were the most abundant group across the five species, followed by ketones and aldehydes. Specifically, BC exhibited the highest alcohol content (23.77 %), MW had the richest ketone content (2.01 %), and HC showed the highest aldehyde content (1.15 %).

Fig. 4.

Analysis of VOCs in Boletus mushrooms using HS-SPME-GC × GC-TOF-MS. (a) Grouped distribution of VOCs; (b) Proportionate distribution of VOCs; (c) Heatmap of VOCs.

Previous studies have shown that alcohols are primarily produced through lipid oxidation and degradation, contributing significantly to the typical mushroom aroma (Zhang et al., 2024). Ketones are mainly formed via the oxidation of unsaturated fatty acids, the Maillard reaction, and amino acid degradation, typically exhibiting floral and fruity flavors. Aldehydes, key compounds influencing the flavor characteristics of Boletus species, are primarily produced through the Strecker degradation of amino acids and the oxidation of polyunsaturated fatty acids, imparting fruity notes (Zhao et al., 2024).

The contribution of VOCs to the overall aroma is determined by both their concentration and odor threshold, assessed through the Relative Odor Activity Value (ROAV). This study further evaluated the contribution of VOCs to the overall flavor profiles of the Boletus mushrooms. Table 3 summarizes the 10 key VOCs with an ROAV greater than 1, comprising five aldehydes, three ketones, one ester, and one aromatic hydrocarbon. Detailed analysis revealed that 1-octen-3-one, with a ROAV value of 100 in MW, BC, HLT, and YSH, was identified as the primary contributor to the aroma of these four species. Previous research has indicated that 1-octen-3-one is produced through the oxidation of linoleic or linolenic acid by enzymes such as hydroperoxide lyase and lipoxygenase, making it a major contributor to the distinctive mushroom aroma. Ethyl acetate also significantly contributed to the aroma of the four species, providing unique fruity and floral characteristics (Guan et al., 2024). In HC, 3-methylbutanal, with an ROAV of 100, was the dominant aroma compound, contributing chocolate and fatty notes. Additionally, n-heptanal, nonanal, 2-octanone, and 2-undecanone played important roles in HC's aroma profile. Among these, n-heptanal exhibited a distinct nutty and fatty aroma, nonanal contributed rose and citrus notes, 2-octanone provided a strong mushroom flavor, and 2-undecanone displayed a concentration-dependent aroma, presenting fatty notes at high concentrations and peach-like notes at low concentrations (Mu et al., 2024).

Table 3.

The VOCs with ROAVs above one in boletus mushrooms using HS-SPME-GC × GC-TOF-MS.

Volatile compounds	Odor	Threshold (mg/kg)	ROAV values
			MW	BC	HC	HLT	YSH
Aldehydes
3-Methylbutanal	Chocolate, fat	0.0012	1.12	0.37	100	3.96	4.09
n-Heptanal	Citrus, Fat, Green, Nut	0.0028	1.36	0.19	16.59	0.74	0.18
Pentanal	Green grassy, faint banana, pungent	0.012	2.62	5.3518E-05	0.004	0.01	7.23004E-05
Nonanal	Rose, citrus, strong oily	0.008	1.69	8.0277E-05	10.40	8.68367E-05	0.0001
2-Nonenal	Paper	0.0001	0.02	0.006	0.44	4.64	0.009
Ketones
2-Octanone	Fat, fragrant, mold	0.0502	0.67	0.22	12.74	0.22	0.33
1-Octen-3-one	Strong earthy, mushroom, vegetable, fishy	0.00004	100	100	1.09	100	100
2-Undecanone	Wax, fruity, cream, fat	0.0055	1.25	0.06	5.34	0.34	0.07
Esters
Ethyl acetate	Fresh, fruity, sweet, grassy	0.005	16.22	5.41	0.59	4.41	15.40
Aromatic Hydrocarbons
Ethylbenzene	Clove, Phenol, Spice	0.026	0.84	0.21	48.66	0.29	0.54

After boiling treatment, HC exhibited a significantly different flavor profile compared to the other four species (MW, BC, HLT, and YSH). Aldehydes were identified as the primary flavor compounds in HC, imparting chocolate and fatty aromas, while ketones and esters were the dominant flavor compounds in MW, BC, HLT, and YSH, contributing to their complex flavor profiles characterized by mushroom, fruity, and floral notes. These findings are consistent with the results of E-nose analysis, further validating the critical role of volatile compounds in shaping the flavor profiles of Boletus mushrooms.

3.7. HS-GC -IMS analysis

HS-SPME-GC × GC-TOF-MS is widely recognized for its efficiency in the qualitative and quantitative analysis of volatile organic compounds (VOCs). However, HS-GC-IMS has shown superior sensitivity in detecting low-concentration small-molecule compounds, making it more suitable for identifying subtle differences between samples (Xie et al., 2023). Consequently, this study utilized HS-GC-IMS to analyze the VOCs present in five distinct types of Boletus mushrooms. A total of 98 VOCs were identified, comprising 20 esters, 23 ketones, 22 alcohols, 19 aldehydes, 4 acids, 2 ethers, 7 heterocyclic compounds, and 1 alkene.

The relative content analysis of VOCs in the five Boletus species (Table 4) revealed that alcohols were the most abundant group, followed by ketones and aldehydes, a pattern consistent with the results obtained from HS-SPME-GC × GC-TOF-MS. Further comparison of the VOC content among the five species was performed using cluster heatmaps (Fig. 4c). Specifically, MW exhibited higher levels of esters and ketones, including ethyl isobutyrate, ethyl 2-methylbutyrate, ethyl propionate, 2-heptanone, and 4-methyl-2-pentanone, which primarily contributed to fruity aromas. In BC, 2-methyltetrahydrothiophen-3-one and 1-octen-3-ol were the dominant VOCs, imparting a strong mushroom aroma. HC showed elevated aldehyde content, including nonanal, 2-methyl-2-pentenal, and 2-ethylbutanal, which contributed to oily and fruity flavors. HLT was characterized by esters and ketones, such as γ-butyrolactone, amyl acetate, 2-methylbutyl acetate, and 4-heptanone, conveying creamy and fruity notes (McGinn et al., 2020). In YSH, heterocyclic compounds and ketones were the primary VOCs, with 2,5-dimethylfuran and 3-octanone being the most prominent, contributing meaty and vegetable-like aromas (Lee et al., 2024).

Table 4.

Analysis of VOCs in boletus mushrooms using HS-GC-IMS.

NO.	Compounds	R.I.	CAS#	Threshold (mg/kg)	Aroma description	Relative amount (%)
						MW	BC	HC	HLT	YSH
	Esters(20)
1	Ethyl acetate	896.6	C141786	3	Fresh, fruity, sweet, grassy	3.77 ± 0.07b	3.24 ± 0.15c	0.08 ± 0.01e	4.13 ± 0.09a	0.63 ± 0.01d
2	Ethyl butanoate	1037.2	C105544	0.0024	Pineapple, fruity, ester, whiskey	0.13 ± 0.00c	0.09 ± 0.01c	0.27 ± 0.05a	0.11 ± 0.01c	0.20 ± 0.01b
3	Ethyl octanoate	1464.2	C106321	0.0193	Fruity, pineapple, apple, brandy	0.08 ± 0.01bc	0.07 ± 0.01c	0.14 ± 0.01a	0.07 ± 0.01bc	0.11 ± 0.04ab
4	Ethyl isobutyrate	980.2	C97621	0.0086	Sweet, fruity, alcoholic, rummy	0.50 ± 0.01a	0.02 ± 0.00c	0.04 ± 0.00b	0.03 ± 0.00c	0.03 ± 0.01bc
5	Ethyl propanoate	973.2	C105373	0.008	Grape, pineapple, fruity, rum	0.15 ± 0.00a	0.02 ± 0.00d	0.03 ± 0.02c	0.02 ± 0.00d	0.06 ± 0.00b
6	Ethyl 2-methylbutanoate-M	1067	C7452791	0.000063	Apple	0.34 ± 0.00a	0.02 ± 0.01b	0.03 ± 0.00b	0.03 ± 0.01b	0.02 ± 0.01b
7	Ethyl 2-methylbutanoate-D	1066.8	C7452791	n.f.	Apple	0.06 ± 0.00a	0.03 ± 0.01b	0.05 ± 0.01b	0.02 ± 0.00c	0.04 ± 0.01b
8	Ethyl 3-methylbutanoate	1081.3	C108645	0.00011	Apple, banana, sour and sweet	0.06 ± 0.00a	0.01 ± 0.00d	0.02 ± 0.00b	0.01 ± 0.00cd	0.01 ± 0.00c
9	Ethyl 3-hydroxybutanoate	1572.2	C5405414	2.5	Fruity, grape, green and wine	0.52 ± 0.03a	0.29 ± 0.02b	0.16 ± 0.01c	0.11 ± 0.00c	0.12 ± 0.04c
10	2-Methylbutyl acetate-M	1137.4	C624419	0.011	Fruity	0.69 ± 0.00b	0.21 ± 0.01c	0.04 ± 0.00d	0.95 ± 0.08a	0.04 ± 0.01d
11	2-Methylbutyl acetate-D	1137.1	C624419	n.f.	Fruity	0.11 ± 0.00b	0.03 ± 0.01c	0.05 ± 0.00c	0.34 ± 0.07a	0.03 ± 0.02c
12	Butyl acetate	1090	C123864	0.058	Fruity	0.01 ± 0.00b	0.01 ± 0.00b	0.06 ± 0.00a	0.01 ± 0.00b	0.01 ± 0.00b
13	Methyl pentanoate	1109.5	C624248	0.044	Fruity	0.25 ± 0.01cd	0.19 ± 0.05d	0.38 ± 0.04a	0.28 ± 0.01bc	0.33 ± 0.01ab
14	Methyl nonanoate	1590.8	C1731846	n.f.	Floral, coconut	0.26 ± 0.05b	0.14 ± 0.05c	0.39 ± 0.02a	0.27 ± 0.03b	0.23 ± 0.09bc
15	Isoamyl acetate	1146.6	C123922	0.00015	Sweet, banana, fruity	0.02 ± 0.00c	0.03 ± 0.00c	0.11 ± 0.02b	0.18 ± 0.03a	0.17 ± 0.00a
16	Hexyl propanoate	1354.6	C2445763	n.f.	Sweet fruity	0.06 ± 0.01b	0.46 ± 0.06a	0.51 ± 0.07a	0.12 ± 0.06b	0.03 ± 0.01b
17	Geranyl acetate	1903	C105873	0.008	Fresh and sweet lemon, fruity, sweet rose	0.26 ± 0.06bc	0.21 ± 0.07c	0.45 ± 0.06a	0.38 ± 0.01ab	0.30 ± 0.12abc
18	cis-3-Hexenyl acetate	1330.9	C3681718	0.21	Fresh green grassyy, sweet, fruity, banana	0.04 ± 0.00c	0.08 ± 0.01b	0.04 ± 0.00c	0.13 ± 0.00a	0.03 ± 0.02c
19	Pentyl acetate	1186	C628637	130	Bananas, apples, pears	0.01 ± 0.01b	0.01 ± 0.00b	0.04 ± 0.01a	0.05 ± 0.01a	0.02 ± 0.01b
20	gamma-Butyrolactone	1800.3	C96480	10	Cream, fat, caramel	0.92 ± 0.08bc	0.84 ± 0.03c	1.73 ± 0.14a	1.07 ± 0.05b	1.85 ± 0.14a
	Total					8.24	6	4.62	8.31	4.26
	Ketones(23)
21	3-Methyl-2-pentanone-M	1036.9	C565617	0.081	Mint, honey	0.16 ± 0.00ab	0.03 ± 0.01d	0.23 ± 0.07a	0.08 ± 0.01cd	0.15 ± 0.00bc
22	3-Methyl-2-pentanone-D	1036.9	C565617	n.f.	Mint, honey	0.07 ± 0.00b	0.03 ± 0.00c	0.07 ± 0.00a	0.03 ± 0.00c	0.07 ± 0.00ab
23	4-Methyl-2-pentanone-D	1026.8	C108101	0.64	Ketone	0.07 ± 0.00b	0.03 ± 0.00d	0.07 ± 0.00a	0.03 ± 0.00c	0.07 ± 0.00b
24	2-Pentanone	999.1	C107879	1.38	Acetone, fresh, sweet fruity, wine	1.54 ± 0.03a	0.23 ± 0.05c	0.07 ± 0.01d	0.54 ± 0.16b	0.07 ± 0.01d
25	4-Methyl-2-pentanone-M	1026.1	C108101	n.f.	Ketone	0.18 ± 0.00b	0.02 ± 0.00d	0.06 ± 0.00c	0.05 ± 0.00c	0.20 ± 0.00a
26	2-Hexanone	1101	C591786	0.56	Fruity, fungal, meaty, buttery	0.09 ± 0.00b	0.05 ± 0.01c	0.11 ± 0.02a	0.03 ± 0.00d	0.08 ± 0.01b
27	Cyclohexanone	1300	C108941	0.67	Strong pungent, earthy	0.60 ± 0.00b	0.45 ± 0.01c	0.23 ± 0.04d	0.10 ± 0.05e	1.10 ± 0.00a
28	Acetone	837.3	C67641	n.f.	Fresh, apple, pear	6.33 ± 0.13b	4.15 ± 0.14c	4.34 ± 0.42c	6.26 ± 0.08b	12.35 ± 0.39a
29	1-Hydroxy-2-propanone	1317.6	C116096	n.f.	Pungent, caramel, fresh	0.11 ± 0.00b	0.21 ± 0.01a	0.11 ± 0.01b	0.07 ± 0.00c	0.11 ± 0.00b
30	2-Heptanone-M	1193.6	C110430	3.73	Pear, banana, fruity, slight medicinal fragrance	0.91 ± 0.01a	0.27 ± 0.05c	0.23 ± 0.04c	0.21 ± 0.06c	0.48 ± 0.01b
31	2-Heptanone-D	1194	C110430	n.f.	Pear, banana, fruity, slight medicinal fragrance	0.26 ± 0.00a	0.06 ± 0.01c	0.11 ± 0.01b	0.07 ± 0.00c	0.11 ± 0.04b
32	4-Heptanone	1135.8	C123193	0.041	Fruity	0.03 ± 0.00b	0.02 ± 0.00b	0.04 ± 0.01b	0.26 ± 0.02a	0.03 ± 0.01b
33	3-Octanone-M	1266.3	C106683	0.0214	Mouldy, ketone, green, waxy, vegetable	0.27 ± 0.00d	0.40 ± 0.01b	0.06 ± 0.00e	0.36 ± 0.03c	2.33 ± 0.03a
34	3-Octanone-D	1266.4	C106683	n.f.	Mouldy, ketone, green, waxy, vegetable	0.05 ± 0.01c	0.09 ± 0.01b	0.08 ± 0.01b	0.08 ± 0.00b	1.04 ± 0.00a
35	3-Hydroxy-2-butanone-D	1301.1	C513860	0.014	Butter, cream	3.01 ± 0.02b	7.53 ± 0.29a	0.32 ± 0.15d	0.17 ± 0.12d	0.67 ± 0.03c
36	3-Hydroxy-2-butanone-M	1300.5	C513860	n.f.	Butter, cream	2.98 ± 0.01a	3.02 ± 0.04a	1.20 ± 0.71b	0.68 ± 0.40b	2.56 ± 0.04a
37	2-Butanone	914.2	C78933	3	Fruity, camphor	1.14 ± 0.03cd	0.90 ± 0.09d	1.50 ± 0.41bc	1.58 ± 0.04b	2.22 ± 0.07a
38	Cyclopentanone	1192	C120923	47	Pleasant	0.18 ± 0.00b	0.20 ± 0.02b	0.45 ± 0.05a	0.22 ± 0.01b	0.41 ± 0.01a
39	6-Methyl-5-hepten-2-one	1352.7	C110930	0.068	Citrus, fruity, mouldy, ketone	0.50 ± 0.00d	1.00 ± 0.01b	2.23 ± 0.03a	0.72 ± 0.18c	0.08 ± 0.01e
40	2,3-Pentanedione	1053.3	C600146	0.02	Sweet, cream, caramel, nuts, cheese	0.37 ± 0.01a	0.38 ± 0.03a	0.14 ± 0.02b	0.36 ± 0.01a	0.10 ± 0.00c
41	2-Undecanone	1695.7	C112129	0.01	Wax, fruity, cream, fat, iris	0.39 ± 0.07b	0.28 ± 0.07b	0.59 ± 0.03a	0.38 ± 0.02b	0.42 ± 0.13b
42	2-Methyltetrahydrothiophen-3-one-M	1559.6	C13679851	n.f.	Aromatic	0.68 ± 0.02b	3.64 ± 0.30a	0.16 ± 0.01c	0.54 ± 0.08b	0.10 ± 0.05c
43	1-Octen-3-one	1316.7	C4312996	0.00004	Strong earthy, mushroom, vegetable, fishy	0.16 ± 0.00b	0.08 ± 0.01c	0.04 ± 0.01d	0.24 ± 0.02a	0.09 ± 0.00c
	Total					20.08	23.07	12.44	13.06	24.84
	Alcohols(22)
44	Ethanol-M	946.4	C64175	2000	Aromaticity	6.27 ± 0.10cd	8.02 ± 2.35c	15.83 ± 0.93a	5.45 ± 0.07d	12.20 ± 0.20b
45	Ethanol-D	946	C64175	n.f.	Aromaticity	18.30 ± 0.22b	17.98 ± 2.67b	17.32 ± 1.31b	23.30 ± 0.55a	6.54 ± 0.12c
46	2-Methyl-1-propanol-M	1110.8	C78831	2.3	Fresh, alcoholic, leather	3.09 ± 0.07a	2.46 ± 0.20b	1.04 ± 0.11c	3.08 ± 0.07a	0.83 ± 0.01c
47	2-Methyl-1-propanol-D	1110.8	C78831	n.f.	Fresh, alcoholic, leather	3.62 ± 0.03a	3.85 ± 0.12a	0.09 ± 0.01c	2.24 ± 0.23b	0.07 ± 0.00c
48	1-Propanol-M	1055.8	C71238	6300	Alcohol, pungent	3.26 ± 0.03a	2.86 ± 0.11b	3.03 ± 0.19b	3.26 ± 0.04a	0.58 ± 0.00c
49	1-Propanol-D	1056.5	C71238	n.f.	Alcohol, pungent	3.28 ± 0.04b	4.34 ± 0.05a	3.08 ± 0.17c	1.35 ± 0.10d	0.11 ± 0.02e
50	1-Butanol-M	1161.8	C71363	4.3	Wine	2.41 ± 0.02a	1.62 ± 0.15bc	1.48 ± 0.43bc	1.82 ± 0.14b	1.22 ± 0.02c
51	2-Butanol	1040.3	C78922	3.3	Fruity	0.10 ± 0.00b	0.09 ± 0.02b	1.25 ± 0.46a	0.33 ± 0.01b	0.13 ± 0.00b
52	3-Methyl-1-butanol-M	1221.7	C123513	0.004	Whiskey, banana, fruity	2.92 ± 0.05bc	2.78 ± 0.04c	1.68 ± 0.11d	2.94 ± 0.03b	4.60 ± 0.11a
53	3-Methyl-1-butanol-D	1222.2	C123513	0.98	Whiskey, banana, fruity	6.35 ± 0.06a	5.44 ± 0.16c	0.31 ± 0.03e	5.93 ± 0.19b	2.32 ± 0.04d
54	1-Butanol-D	1161.8	C71363	4.3	Wine	0.79 ± 0.01a	0.30 ± 0.06b	0.09 ± 0.06c	0.39 ± 0.08b	0.05 ± 0.00c
55	3-Methyl 3-butenol	1266.3	C763326	n.f.	Sweet, fruity	0.37 ± 0.00a	0.26 ± 0.02c	0.11 ± 0.02e	0.29 ± 0.02b	0.16 ± 0.00d
56	1-Pentanol-M	1267.5	C71410	0.1502	Balsamic	0.74 ± 0.00b	0.26 ± 0.01c	0.10 ± 0.01d	1.20 ± 0.11a	0.32 ± 0.00c
57	1-Pentanol-D	1267	C71410	0.1502	Balsamic	0.12 ± 0.00b	0.05 ± 0.01c	0.06 ± 0.00c	0.30 ± 0.05a	0.11 ± 0.00b
58	3-Methyl-1-pentanol-M	1344.6	C589355	0.0075	Wine, cocoa, green, fruity	0.22 ± 0.00c	0.56 ± 0.02b	0.72 ± 0.01a	0.56 ± 0.12b	0.04 ± 0.01d
59	3-Methyl-1-pentanol-D	1344.3	C589355	n.f.	Wine, cocoa, green, fruity	0.02 ± 0.01c	0.05 ± 0.00ab	0.06 ± 0.01a	0.06 ± 0.02a	0.03 ± 0.01bc
60	1-Hexanol	1370.5	C111273	0.2	Fresh, fruity, wine, sweet, green	1.51 ± 0.01a	0.34 ± 0.02c	0.25 ± 0.06c	0.97 ± 0.38b	0.36 ± 0.04c
61	2-Ethyl-1-hexanol	1540.9	C104767	25.4822	Citrus, fresh floral, greasy	0.16 ± 0.03b	0.16 ± 0.02b	0.38 ± 0.02a	0.22 ± 0.01b	0.33 ± 0.07a
62	3-Octanol	1401.4	C589980	0.018	Earth, mushrooms, herb, melon, citrus	0.44 ± 0.01a	0.14 ± 0.02c	0.15 ± 0.01bc	0.20 ± 0.02b	0.13 ± 0.04c
63	1-Octanol	1655.4	C111875	0.1258	Citrus, sweet, herbs, waxy, rose, mushroom	0.18 ± 0.03b	0.25 ± 0.02b	0.34 ± 0.01a	0.19 ± 0.01b	0.23 ± 0.06b
64	1-Octen-3-ol	1490.3	C3391864	0.025	Mushroom, lavender, rose, hay	0.21 ± 0.02d	1.27 ± 0.07a	0.18 ± 0.02d	0.30 ± 0.04c	0.44 ± 0.04b
65	2-Heptanol	1337	C543497	0.065235	Mushroom, melon	0.14 ± 0.01b	0.08 ± 0.01c	0.15 ± 0.01ab	0.17 ± 0.02a	0.04 ± 0.02d
	Total					54.5	53.16	47.7	54.55	30.84
	Aldehydes(19)
66	Acetaldehyde	760.3	C75070	n.f.	Green, slight fruity	3.51 ± 0.11c	3.65 ± 0.34c	6.73 ± 0.37a	3.30 ± 0.27c	6.15 ± 0.19b
67	Phenylacetaldehyde	1765.1	C122781	0.009	Hyacinth, sweet fruity, almond, cherry	0.19 ± 0.10c	0.23 ± 0.10c	0.80 ± 0.10a	0.30 ± 0.00bc	0.48 ± 0.20b
68	2-Methylpropanal	827.9	C78842	n.f.	Banana, melon, slightly nutty	0.07 ± 0.00cd	0.23 ± 0.15c	0.96 ± 0.10a	0.03 ± 0.00d	0.50 ± 0.05b
69	Propanal-M	816.5	C123386	0.0151	Pungent, green grassy	0.53 ± 0.01b	0.91 ± 0.17a	0.76 ± 0.09a	0.11 ± 0.01c	0.52 ± 0.02b
70	Propanal-D	817.1	C123386	0.0151	Pungent, green grassy	0.12 ± 0.00ab	0.47 ± 0.38a	0.14 ± 0.02ab	0.02 ± 0.00b	0.14 ± 0.01ab
71	2-Ethylbutanal-M	1013.2	C97961	0.081	Fruity, green	0.03 ± 0.00c	0.03 ± 0.01c	0.49 ± 0.04a	0.03 ± 0.00c	0.33 ± 0.00b
72	3-Methylbutanal	928.7	C590863	0.00025	Chocolate, fat	2.68 ± 0.05c	1.20 ± 0.22d	5.02 ± 0.20b	0.16 ± 0.01e	6.76 ± 0.17a
73	Butanal	894.1	C123728	0.0022	Pungent, fruity, green leaf	0.16 ± 0.00a	0.15 ± 0.00a	0.14 ± 0.09a	0.19 ± 0.00a	0.15 ± 0.00a
74	2-Ethylbutanal-D	1013.5	C97961	n.f.	Fruity, green	0.01 ± 0.00c	0.01 ± 0.00c	0.08 ± 0.00a	0.01 ± 0.00c	0.03 ± 0.00b
75	Pentanal-D	1002.7	C110623	0.012	Green grassy, faint banana, pungent	0.08 ± 0.00a	0.02 ± 0.00c	0.05 ± 0.01b	0.04 ± 0.01b	0.02 ± 0.01c
76	Pentanal-M	1002.4	C110623	n.f.	Green grassy, faint banana, pungent	0.84 ± 0.01a	0.55 ± 0.18bc	0.45 ± 0.01cd	0.64 ± 0.07b	0.32 ± 0.01d
77	(E)-2-Octenal	1441.6	C2548870	0.003	Fresh cucumber, fatty, green herbal, banana	0.06 ± 0.01c	0.08 ± 0.02bc	0.16 ± 0.01a	0.08 ± 0.00bc	0.10 ± 0.03b
78	2-Hexenal	1219.5	C505577	0.03	Sweet almonds, fruity, green leaves, apples	0.19 ± 0.00b	0.16 ± 0.01c	0.20 ± 0.01b	0.19 ± 0.00b	0.32 ± 0.00a
79	3-Methyl-2-butenal	1215.6	C107868	0.0005	Fruity	0.05 ± 0.00b	0.06 ± 0.01ab	0.06 ± 0.00ab	0.06 ± 0.00a	0.06 ± 0.00ab
80	2-Methyl-2-propenal	895.1	C78853	n.f.	Hyacinth foliage	0.16 ± 0.00b	0.16 ± 0.01b	0.16 ± 0.04b	0.21 ± 0.01a	0.21 ± 0.01a
81	2-Methyl-2-pentenal	1155.5	C623369	0.29	Aldehydes, soil, garlic, ripe cherries, fruity	0.02 ± 0.00bc	0.03 ± 0.01b	0.08 ± 0.01a	0.01 ± 0.00c	0.01 ± 0.00c
82	Nonanal	1406.4	C124196	0.008	Rose, citrus, strong oily	0.07 ± 0.01c	0.08 ± 0.01c	0.27 ± 0.03a	0.07 ± 0.01c	0.12 ± 0.02b
83	Hexanal	1102.1	C66251	0.098	Fresh, green, fat, fruity	0.15 ± 0.00a	0.04 ± 0.01b	0.16 ± 0.03a	0.04 ± 0.01b	0.06 ± 0.01b
84	Benzaldehyde	1554	C100527	0.0417	Bitter almond, cherry, nutty	0.20 ± 0.03c	0.51 ± 0.03a	0.50 ± 0.01a	0.18 ± 0.01c	0.29 ± 0.04b
	Total					9.12	8.57	17.21	5.67	16.57
	Acids(4)
85	Acetic acid	1504.4	C64197	180	Spicy	4.43 ± 0.02d	4.90 ± 0.21d	6.89 ± 0.29c	14.97 ± 0.40a	11.00 ± 0.20b
86	Propanoic acid	1637	C79094	2.19	Yogurt, vinegar	0.45 ± 0.01d	0.56 ± 0.04c	0.83 ± 0.04a	0.68 ± 0.02b	0.72 ± 0.07b
87	Butanoic acid	1715.7	C107926	7.7	Strong acetic acid, cheese, butter, fruity	0.33 ± 0.02a	0.27 ± 0.04a	0.26 ± 0.01a	0.15 ± 0.02b	0.16 ± 0.09b
88	2-Methylpropanoic acid	1635.5	C79312	29	Yogurt, rancid cream	0.64 ± 0.06a	0.25 ± 0.05c	0.45 ± 0.03b	0.30 ± 0.02c	0.30 ± 0.06c
	Total					5.85	5.98	8.43	16.1	12.18
	Ethers(2)
89	Butyl ether-M	972.3	C142961	n.f.	Ether	0.13 ± 0.00b	0.20 ± 0.07b	0.51 ± 0.42b	0.15 ± 0.02b	1.42 ± 0.02a
90	Butyl ether-D	972.7	C142961	n.f.	Ether	0.03 ± 0.00c	0.07 ± 0.01bc	0.15 ± 0.11b	0.07 ± 0.03bc	0.64 ± 0.01a
	Total					0.16	0.27	0.66	0.22	2.06
	heterocyclic compounds(7)
91	2-Pentylfuran	1245.9	C3777693	0.0048	Bean, fruity, earthy, green, vegetable	0.27 ± 0.00a	0.11 ± 0.01c	0.05 ± 0.02d	0.17 ± 0.02b	0.07 ± 0.00d
92	2,5-Dimethylfuran	946.4	C625865	n.f.	Meaty, roast beef, bacon	0.02 ± 0.00c	0.01 ± 0.00c	0.33 ± 0.23b	0.01 ± 0.00c	0.55 ± 0.01a
93	2-Ethylpyrazine	1371.8	C13925003	n.f.	Nutty, mouldy, woody, potato, earthy, roast	0.15 ± 0.00b	0.32 ± 0.07a	0.07 ± 0.00c	0.06 ± 0.01c	0.17 ± 0.00b
94	2,3-Dimethylpyrazine	1353.7	C5910894	0.8	Nutty	0.17 ± 0.00b	0.56 ± 0.08a	0.53 ± 0.02a	0.18 ± 0.04b	0.17 ± 0.02b
95	2,3,5-Trimethylpyrazine	1446.2	C14667551	n.f.	Roasted potato, peanut, cocoa, chocolate	0.04 ± 0.01c	0.10 ± 0.01a	0.08 ± 0.01ab	0.06 ± 0.01bc	0.07 ± 0.02b
96	2-Acetyl-3-methylpyrazine	1689.5	C23787806	0.02	Nuts, roasted hazelnuts, roasted grain	0.29 ± 0.03b	0.21 ± 0.07bc	0.28 ± 0.03b	0.45 ± 0.04a	0.18 ± 0.06c
97	2-Methyltetrahydrothiophen-3-one-D	1559.8	C13679851	n.f.	Aromatic	0.08 ± 0.04c	0.68 ± 0.11a	0.21 ± 0.02b	0.11 ± 0.01bc	0.16 ± 0.07bc
	Total					1.02	1.99	1.55	1.04	1.37
	Alkenes(1)
98	2-Propenal	863.3	C107028	0.11	Strong pungent	1.05 ± 0.01c	0.97 ± 0.25c	7.12 ± 0.64b	1.11 ± 0.11c	7.85 ± 0.21a
	Total					1.05	0.97	7.12	1.11	7.85

Different letters attached to the values within the same column indicate the significantly different at p < 0.05 level.

Furthermore, the fingerprint analysis of the five Boletus species (Fig. 5a) demonstrated that MW was dominated by alcohols, ketones, and esters, exhibiting mushroom, floral, and fruity flavors (Rao & Vejerano, 2018). BC was characterized by alcohols, aldehydes, and ketones, presenting mushroom, fruity, and floral notes (McGinn et al., 2020). HC was primarily composed of aldehydes, with fewer alcohols, ketones, and esters, resulting in a dominant mushroom flavor (Sangeeta Sharma et al., 2024). HLT was rich in esters, contributing mainly to fruity aromas, while YSH contained fewer alcohols, aldehydes, and ketones, and no esters, resulting in a less distinct aroma profile (Xiao et al., 2024). The relative content of volatile compounds and fingerprint analysis together outlined the flavor differences among the five Boletus species.

Fig. 5.

Analysis of VOCs in Boletus mushrooms using HS-GC-IMS and Correlation heatmap. (a) Fingerprint plot; (b) Correlation heatmap between VOCs and E-nose responses (Significant differences are indicated by “*”, “**”and“***” (* p < 0.05, ** p < 0.01 and *** p < 0.001); (c) Correlation heatmap between amino acids and E-tongue responses (The notes of significant differences were the same as those in Fig. 5b).

To further assess the contribution of VOCs to the overall flavor of the five Boletus species, ROAV analysis was conducted. Table 5 lists 12 volatile compounds with ROAV values greater than 1, including four aldehydes, four esters, two ketones, and two alcohols. Among these, 3-methylbutanal, with an ROAV of 100, was a major contributor to the fatty aroma in MW, BC, HC, and YSH. 1-Octen-3-one, with a ROAV of 100 in HLT, was identified as the dominant compound in the overall flavor of this species. Additionally, 1-octen-3-one also significantly contributed to the flavor of the other four species, imparting mushroom and grassy aromas. Specifically, ethyl 2-methylbutyrate and ethyl 3-methylbutyrate contributed notably to the fruity aroma of MW (Belleggia et al., 2022). Isoamyl acetate and 3-hydroxy-2-butanone were key contributors to the flavor of BC. Isoamyl acetate, a volatile compound with banana and pear-like aromas, is primarily formed through the esterification of acids and alcohols. 3-Hydroxy-2-butanone, produced through the oxidation and degradation of unsaturated lipids or non-enzymatic reactions, is considered a key factor in the development of cooked food flavors, contributing buttery and creamy notes to BC. Isoamyl acetate was also a characteristic flavor compound in HC, HLT, and YSH, significantly influencing their flavor profiles. These ROAV results were consistent with the fingerprint analysis, further validating the importance of these compounds in defining the flavor characteristics of the Boletus species.

Table 5.

The VOCs with ROAVs above one in boletus mushrooms using HS-GC-IMS.

Volatile compounds	ROAV values
	MW	BC	HC	HLT	YSH
Aldehydes
Propanal	0.33	1.25	0.25	0.12	0.13
3-Methylbutanal	100.00	100.00	100.00	10.50	100.00
Butanal	0.68	1.45	0.31	1.48	0.25
3-Methyl-2-butenal	0.99	2.32	0.57	2.17	0.45
Esters
Ethyl 2-methylbutanoate	49.72	7.79	2.37	7.23	1.18
Ethyl 3-methylbutanoate	4.98	1.39	0.90	1.73	0.45
2-Methylbutyl acetate	0.59	0.40	0.02	1.44	0.01
Isoamyl acetate	1.50	4.60	3.78	20.50	4.16
Ketones
3-Hydroxy-2-butanone	2.01	11.20	0.11	0.20	0.18
1-Octen-3-one	38.34	43.13	5.30	100.00	8.07
Alcohols
3-Methyl-1-pentanol	0.27	1.55	0.48	1.26	0.02
1-Octen-3-ol	0.08	1.06	0.04	0.20	0.07

The HS-GC-IMS results demonstrated that the five Boletus species exhibited desirable flavor profiles after boiling, with both shared and unique characteristics and no unpleasant odors. Specifically, the five distinct types of Boletus mushrooms displayed fruity notes. MW was characterized by fatty and fruity flavors, primarily contributed by 3-methylbutanal, ethyl 2-methylbutyrate, and ethyl 3-methylbutyrate. BC exhibited fatty, banana, pear, and creamy flavors, mainly attributed to 3-methylbutanal, isoamyl acetate, and 3-hydroxy-2-butanone. HC and YSH shared similar flavor profiles, dominated by fatty, banana, and pear notes, with 3-methylbutanal and isoamyl acetate as the key contributors. HLT was characterized by mushroom, grassy, and banana-pear flavors, mainly driven by 1-octen-3-one and isoamyl acetate. These findings were largely consistent with the HS-SPME-GC × GC-TOF-MS results, although some differences were observed, likely due to the distinct analytical focuses of HS-SPME-GC × GC-TOF-MS and HS-GC-IMS.

3.8. Correlation analysis between VOCs and E-nose responses, and between amino acids and E-tongue responses

To elucidate the associations between VOCs, amino acids, and sensory responses, correlation heatmaps were constructed between VOCs (ROAV >1) and E-nose sensor signals, as well as between amino acids and E-tongue sensor responses. As shown in Fig. 5b, ethylbenzene exhibited a significant positive correlation with both the W1W and W2W sensors (p < 0.001), indicating strong sensor responsiveness to this compound. The W1W sensor is sensitive to sulfides and terpenoids, while the W2W sensor primarily detects aromatic compounds. Ethylbenzene, characterized by a typical spicy and clove-like aroma, showed the highest ROAV value in the HC sample (48.66, Table 3), suggesting that this species possesses a more pronounced spicy aroma profile. Previous studies have reported that ethylbenzene is rarely found in fresh mushrooms; its presence in boiled samples may be attributed to thermal degradation of lipids or the breakdown of aromatic amino acids during processing (Zhang, Liu, et al., 2024). In addition to ethylbenzene, 1-octen-3-one and 2-undecanone were both positively correlated with the W5C sensor (p < 0.001), which is also responsive to aromatic compounds. 1-Octen-3-one is widely recognized as a key contributor to the characteristic mushroom-like aroma of Boletus mushrooms, whereas 2-undecanone primarily imparts fruity, buttery, and cheesy notes and is likely derived from β-oxidation of fatty acids or other metabolic pathways (Sangeeta Sharma et al., 2024). Beyond ketones, 2-methylbutyl acetate and n-heptanal also showed positive correlations with the W5C sensor (p < 0.001). 2-Methylbutyl acetate, an important fruity and sweet ester, is typically formed via esterification between short-chain fatty acids and alcohols. n-Heptanal, a C7 aldehyde with fatty and nutty odor notes, is mainly formed through the enzymatic oxidation of linoleic and linolenic acids: initially by lipoxygenase (LOX) to generate hydroperoxides, which are subsequently cleaved by hydroperoxide lyase (HPL). Due to its low odor threshold, n-heptanal can significantly impact overall aroma even at low concentrations, making it a key indicator of fungal aroma. Notably, it exhibited the highest ROAV in the HC sample (16.59), further supporting the enhanced fatty and nutty aroma characteristics of this species.

In the analysis of amino acids (Fig. 5c), glutamine (Gln) exhibited a positive correlation with both sourness and richness (p < 0.001), despite being typically classified as a tasteless amino acid. It is speculated that Gln may indirectly enhance these taste attributes through synergistic interactions with other flavor-active compounds. This finding highlights the potential role of tasteless amino acids in modulating sensory perception within complex flavor systems. As shown in Table 2, the YSH sample contained the highest level of Gln (718.21 μg/g), which corresponds well with the sour and umami characteristics observed in the E-tongue analysis. In contrast, Gly and Asp, which are commonly recognized as sweet and umami amino acids, respectively, showed positive correlations with bitterness and Aftertaste-B (p < 0.001). This counterintuitive result may be attributed to their relatively high concentrations in the samples, which failed to mask the perception of other bitter compounds. Instead, they may have enhanced bitterness perception through synergistic effects or sensory contrast mechanisms. These findings further support the notion that taste perception is a concentration-dependent, multifactorial process involving complex interactions among multiple components. Additionally, most amino acids exhibited negative correlations with the saltiness sensor, suggesting that they may exert masking or suppressive effects on salty taste. This further underscores the multifaceted role of amino acids in shaping overall taste profiles.

In summary, this study systematically elucidated the intrinsic relationships between key VOCs and E-nose sensor responses, as well as between amino acids and E-tongue sensory attributes in Boletus mushroom samples using correlation heatmaps. The results demonstrated that 1-octen-3-one, 2-undecanone, 2-methylbutyl acetate, and n-heptanal contributed significantly to aromatic compound sensors and were identified as key contributors to mushroom-like, fatty, and fruity aromas. In contrast, amino acids exerted complex effects on taste perception depending on their concentrations and compositional interactions, underscoring the importance of considering synergistic effects, sensory thresholds, and matrix influences in flavor analysis. Future studies should further explore the interaction mechanisms among flavor compounds, establish representative model systems, and integrate sensory validation approaches to more accurately elucidate the formation patterns and perceptual mechanisms underlying complex flavor profiles.

4. Conclusions

In this study, a combination of advanced analytical techniques was employed to systematically evaluate the texture, taste, and flavor differences of five Boletus species after boiling, with the aim of identifying the most suitable variety for boiling-based processing. TPA revealed that HLT and HC exhibited tender textures, MW was soft, BC was crisp, and YSH was firm. TAV analysis indicated that umami amino acids contributed most to the taste of BC, while sweet amino acids predominated in HLT. In contrast, bitter amino acids had a greater impact on the taste profiles of MW, HC, and YSH. E-nose analysis identified sulfides, aromatic compounds, and terpenes as the primary aroma contributors across all samples. E-tongue results revealed that MW was characterized by sweetness, BC by saltiness, HLT by bitterness, and HC and YSH by sourness. Further analysis using HS-SPME-GC × GC-TOF-MS and HS-GC-IMS confirmed distinct volatile profiles: HLT exhibited prominent mushroom-like and fruity aromas; BC was dominated by fruity and creamy notes; HC displayed chocolate, fatty, and fruity aromas; while MW and YSH exhibited a combination of mushroom-like, fatty, and fruity characteristics. Considering the combined results of texture, taste, and aroma analyses, HLT was identified as the most suitable Boletus species for boiling, owing to its tender texture and distinctive flavor profile. This study not only provides comprehensive sensory data for evaluating Boletus mushroom quality but also offers a theoretical foundation for precision processing and product development.

Notably, partial losses of amino acids and other nutrients were observed during boiling. Therefore, future research will focus on developing Boletus-based soup or broth products to maximize nutrient retention and promote the high-value utilization and sustainable development of Boletus resources.

CRediT authorship contribution statement

Feng Zhang: Writing – review & editing. Cunchao Zhao: Conceptualization. Xiaolin Huang: Data curation. Yuwei Guo: Investigation. Jingchuan Zheng: Methodology. Zhen Zhang: Software. Yaling Gu: Validation. Lijiu Yang: Software. Weiqian Wang: Software. Chengxu Liu: Visualization. Jia Liu: Conceptualization. Ya Wang: Project administration.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability

The data that has been used is confidential.