Isoamyl Acetate Research Articles

Effect of fruiting-related genes on the formation of volatile organic compounds in the mushroom Schizophyllum commune

In fungi, little is known about connections between volatile organic compound (VOC) formation and developmental stages that are amongst others triggered by fruiting-related genes (FRGs). We analysed the volatilomes of Schizophyllum commune during different developmental stages in a variety of FRG-deletion strains and wild-type strains. The deletion strains Δtea1Δtea1, Δwc-2Δwc-2 and Δhom2Δhom2 were unable to develop fruiting bodies, and Δfst4Δfst4 formed only rudimentary fruiting body structures. Early developmental stages of these strains were dominated by esters, including methyl 2-methylbutanoate, ethyl 2-methylbutanoate, isobutyl 2-methylpropionate, and 2-methylbutyl acetate, of which the last three were not found in the headspace (HS) of the wild-type samples. Compared to the wild type, in the HS of hom2con samples, that are able to form fruiting bodies, methyl 2-methylbutanoate was the most abundant substance at early stages (68–81% of the total peak area). In contrast to fruiting body forming strains, Δtea1Δtea1, Δwc-2Δwc-2, Δhom2Δhom2 and Δfst4Δfst4 showed less sesquiterpenes in the HS. However, the sesquiterpenes found in the HS of FRG-deletion strains, namely, (E)-nerolidol, δ-cadinene, L-calamenene, α-bisabolol and β-bisabolene, were not present in hom2con or wild-type strains that mainly formed fruiting bodies and barely mycelium. Several sesquiterpenes, including α-guaiene, chamigrene and γ-gurjunene, were only found in presence of fruiting bodies. Our results show remarkable connections between FRGs, fruiting body development and VOC production in S. commune, especially counting for sesquiterpenes. Future studies are needed to reveal whether FRGs directly regulates VOC formation or indirectly by changing the phenotype.

Effect of Peony (Paeonia ostii) Seed Meal Supplement on Enzyme Activities and Flavor Compounds of Chinese Traditional Soybean Paste during Fermentation.

Peony seed meal (PSM) is the by-product obtained from peony seeds after oil extraction. In this study, PSM was incorporated into traditional koji-making, and its impacts on koji enzyme activities and flavor compounds in final products were investigated. In the process of koji fermentation, the optimal addition ratio of PSM to soybean was determined as 7:3. Under this ratio, the maximum enzyme activities of neutral protease, amylase, and glucoamylase were 1177.85, 686.58, and 1564.36 U/g, respectively, and the koji obtained was subjected to maturation. During post-fermentation, changes in the fermentation characteristics of the paste samples were monitored, and it was found that compared to the soybean paste without PSM, the enzyme activities maintained at a relatively good level. The PSM soybean paste contained a total of 80 flavor compounds and 11 key flavor compounds (OAV ≥ 1), including ethyl isovalerate, isovaleric acid, hexanal, phenylacetaldehyde, 3-Methyl-1-butanol 4-heptanone, 2-pentylfuran, methanethiol ester caproate, isoamyl acetate, 3-methyl-4-heptanone, and isovaleraldehyde. These findings could be used to improve the quality of traditional fermented paste, enrich its flavor, and simultaneously promote PSM as a valuable resource for fermented foods.

Optimization of the Process for Green Jujube Vinegar and Organic Acid and Volatile Compound Analysis during Brewing.

Healthy fruit vinegar has become very popular recently in China. This study aimed to produce fruit vinegar with a good taste, high nutritional value, and strong functional properties from green jujube. This study investigated the optimization of the process for green jujube vinegar using response surface methodology. The optimum fermentation parameters for green jujube vinegar were determined as follows: initial alcoholicity 6%, acetobacter 8%, fermentation temperature 32 °C, and time 7 d. The organic acids of the optimized sample were evaluated by HPLC, and the volatile substances were identified and analyzed by HS-SPME and GC-MS during the fermentation and aging of the green jujube vinegar. The results showed that the variation trends of the different organic acids during the making of the green jujube vinegar were significantly different. Organic acids are the key flavor compounds of green jujube vinegar, and their changes were mainly attributed to microbial metabolism. In particular, the green jujube vinegar stood out in terms of volatile aroma compounds, including a total of 61 volatile compounds whose major components were acetic acid, isoamyl acetate, ethyl acetate, 3-hydroxy-2-butanone, methyl palmitate, and ethanol. The results can provide theoretical support for the production of green jujube vinegar.

Comparative analysis of the aroma profile of pineapple beers brewed with juice added at different times

Pineapple juice was added at three different points in the brewing process, (i) wort, (ii) toward the end of fermentation and (iii) at the beginning of maturation. The physicochemical properties, taste and aroma of the three fruit beers was compared to a control beer without addition of pineapple juice. The beers analysed using an electronic nose (E-nose), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Of the three fruit beers, esters characteristic of pineapple aroma was found in the beer produced with juice added late during primary fermentation. Further, the abundance of esters - isoamyl acetate, ethyl butyrate, ethyl acetate, ethyl hexanoate and phenethyl acetate - was higher. Sensory analysis showed the beer produced from the addition of juice late in fermentation had a superior aroma and was the most preferred in sensory testing. These results provide technical support for process optimisation and for improving the aroma of fruit beers.

Extremely low oxygen with different hysteresis and dynamic controlled atmosphere storage: Impact on overall quality and volatile profile of ‘Maxi Gala’ apple

This study aimed to evaluate the effect of the novel strategy of extreme low oxygen (ELO) associated to low O2 hysteresis (HY) and compare it with traditional controlled atmosphere (CA) and dynamic controlled atmosphere (DCA) methods during ‘Maxi Gala’ apple storage. The overall quality and volatile compounds were evaluated after 9 months of storage plus 7, 14, and 21 d of shelf life. Two experiments were performed in different years, evaluating ELO conditions, CA, CA + 1-methylcyclopropene (1-MCP), DCA monitored by chlorophyll fluorescence (DCA-CF), and monitored by respiratory quotient (DCA-RQ 1.3). ‘Maxi Gala’ apple stored under CA showed higher ethylene production, respiration rate, and physiological disorders incidence than fruit stored under CA + 1-MCP, ELO, and DCA. However, only storage in CA + 1-MCP and DCA-RQ 1.3 maintained higher flesh firmness. Fruit stored under 0.4 kPa O2 with 0.4 and 0.6 hysteresis had similar amount of healthy fruit to DCA-RQ 1.3 and higher than CA, CA + 1-MCP, and DCA-CF. Furthermore, CA + 1-MCP and DCA-CF suppressed the main esters of ‘Maxi Gala’ apple during all shelf life periods. On the other hand, storage in 0.4 kPa O2 + 0.6 HY resulted in fruit with higher alcohols and aldehydes concentration, in addition to have high amount of some important esters for ‘Maxi Gala’ aroma, such as 3-methylbutyl acetate. DCA-RQ and ELO storage, despite reduce main esters soon after storage, may result in aroma recovery after 21 d of shelf life. Thus, storage under ELO at 0.4 kPa O2, with 0.4 or 0.6 hysteresis, can be a promising alternative for ‘Maxi Gala’ apple storage, especially to CA and DCA-CF, without resulting in additional costs to the storage systems.

Gas Chromatographic-Ion Mobility Spectrometry Combined with Chemometrics to Study the Changes in Characteristic Odor Components of Galli gigerii Endothelium Corneum in Different Processing Methods.

Galli gigerii endothelium corneum (GGEC) is a traditional Chinese medicine commonly used in clinical practice to treat various conditions such as indigestion, vomiting, spermatorrhea, and enuresis. In this study, the volatile components of different concoctions of GGEC were examined by gas chromatography-ion mobility spectrometry (GC-IMS), and the changes of the components were compared by fingerprinting, combined with principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) to analyze the main volatile components and find out the different markers that can distinguish the different concoctions of GGEC. In the result, the GC-IMS fingerprints of GGEC and its different concoctions showed differences in their volatile components, of which 49 volatiles were clearly characterized, with some components including monomers and dimers. The characteristic volatile components of raw GGEC (SP) were n-nonanal, (E)-2-octenal, beta-ocimene, 2-ethyl-1-hexanol, etc. The characteristic volatile components of stir-fried GGEC (QC) are heptanal, 2-octanol, (E)-2-heptenal, etc. The characteristic volatile components of sand ironing GGEC (ST) are isoamyl acetate, decanal, cyclohexanone, 2-ethyl pyrazine, etc. The characteristic volatile components of stir-fried GGEC with vinegar (CZ) are thiazole, linalool, 2,3,5-trimethylpyrazine, etc. The characteristic volatile components of stir-fried GGEC with milk (FH) are 2-methylbutanoic acid, ethyl acetate, ethyl 2-hydroxypropanoate, butyl acetate, etc. By chemometric analysis, components such as n-nonanal, (E)-2-octenal, 2-pentyl-furan, butanal, 1,4-dioxane, and 2-methylpropanoic acid could be used as difference markers to distinguish different concoction products of GGEC. Furthermore, by analyzing different volatile compounds, we can examine the changes in volatile components during processing of GGEC, which can provide experimental data for the identification and establishment of quality standards.

Addition of Saccharomyces eubayanus to SCOBY fermentations modulates the chemical and volatile compound profiles in kombucha

Kombucha is a fermented beverage derived from a sweetened tea fermentation inoculated with a bacteria-yeast consortium referred to as Symbiotic Culture of Bacteria and Yeast (SCOBY). Different SCOBY cultures can impact the beverage's quality and make the whole process highly variable. Adding Saccharomyces yeast cultures to the fermentation process can avoid stalled fermentations, providing a reproducible beverage. Here, we explored using different Saccharomyces eubayanus strains together with SCOBY in the context of kombucha fermentation. Our results show that yeast x SCOBY co-cultures exhibited a robust fermentation profile, providing ethanol and acetic acid levels ranging from 0,18–1,81 %v/v and 0,35–1,15 g/L, respectively. The kombucha volatile compound profile of co-cultures was unique, where compounds such as Isopentyl acetate where only found in yeast x SCOBY fermentations. Metabarcoding revealed that the SCOBY composition was also dependent on the S. eubayanus genotype, where besides Saccharomyces, amplicon sequence variants belonging to Brettanomyces and Starmerella were detected. These differences concomitated global changes in transcript levels in S. eubayanus related to the metabolism of organic molecules used in kombucha fermentation. This study highlights the potential for exploring different S. eubayanus strains for kombucha fermentation, and the significant yeast genotype effect in the profile differentiation in this process.

Flavor and quality characteristics of Guizhou red sour soup prepared by different artificially fortified fermentation methods

Red sour soup is a typical condiment in Guizhou Province, China. However, its flavor quality is often limited by its unstable traditional fermentation methods. In the study, red sour soup was prepared with three fermentation methods (split fortification, mixed fortification, and natural fermentation) and then various indicators of the prepared soup were determined. Compared with natural fermentation, two fortified fermentation methods could accelerate the pH decrease of red sour soup (on the 6th day pH = 3.36 ± 0.01 for split fortification and pH = 3.26 ± 0.06 for mixed fortification), increase the total number of lactic acid bacteria, total acid, umami value, and amino nitrogen content, and more efficiently control the content of nitrite and saltiness. Mixed fortification realized the contents of organic acids (26.776 ± 8.351 g/kg) and cis-lycopene (9.540 ± 0.559%). The contents of the key esters (methyl butyrate, hexyl acetate, etc.) and alcohols (2-ethylhexanol, 1-hexanol, etc.) in the red sour soup prepared with two fortified fermentation methods were higher than those in the red sour soup prepared with natural fermentation. The characteristic flavoring substances in the red sour soup prepared with split fortification were mainly leaf alcohol, ethyl butyrate, isoamyl acetate, and α-turnipene, whereas the characteristic flavoring substances in the red sour soup prepared with mixed fortification were mainly methyl butyrate, isobutyl acetate, hexyl acetate, and linalool oxide. The study provides the basis for the optimization of fermentation parameters and the quality control of red sour soup.

Volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening and senescence using HS–SPME with GC–MS

The volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening stages and senescence times was determined by headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry. The HS-SPME-GC-MS analysis allowed the identification of 46 metabolites that produce the metabolic fingerprint of this fruit, the major compounds at all ripening stages and senescence times were ethyl butanoate, methyl butanoate, β-myrcene and eucalyptol. The composition in the different stages was subjected to principal component analysis (PCA), which explained 77.3% of the total variance in the principal components. It allowed to classify the samples by ripening stages and senescence times and it was corroborated with K-means clustering and dendrogram analyses. Through multivariate analyses PCA, partial least squares-discriminant analysis (PLS-DA), and heatmap it was possible to determine volatiles methyl (E)-2-hexenoate, 4-tert-butylcyclohexyl acetate, methyl benzoate, methyl (Z)-3-hexenoate, 3-methylbutyl acetate, β-thujene, cis-3-hexenol, hexanal and trans-2-hexenal as potential markers in the ripening stages, while volatiles propyl butanoate, ethyl octanoate, ethyl acetate, ethyl butanoate, β-myrcene and estragol predominated in the senescence times. HS-SPME-GC-MS analysis of volatiles in combination with the chemometric approach used in this research allowed to make a clear distinction between ripening stages and senescence times in common red variety of tree tomato pulp.

Distillation Separation of the Isobutyl Acetate–Acetic Acid–Isoamyl Acetate Industrial Mixture

Distillation Separation of the Isobutyl Acetate–Acetic Acid–Isoamyl Acetate Industrial Mixture

Biocontrol Using Torulaspora delbrueckii in Sequential Fermentation: New Insights into Low-Sulfite Verdicchio Wines.

Torulaspora delbrueckii has attracted renewed interest in recent years, for its biotechnological potential linked to its ability to enhance the flavor and aroma complexity of wine. Sequential fermentations with a selected native strain of T. delbrueckii (DiSVA 130) and low-sulfite native strain of Saccharomyces cerevisiae (DiSVA 709) were carried out to establish their contribution in biocontrol and the aroma profile. A first set of trials were conducted to evaluate the effect of the sulfur dioxide addition on pure and T. debrueckii/S. cerevisiae sequential fermentations. A second set of sequential fermentations without SO2 addition were conducted to evaluate the biocontrol and aromatic effectiveness of T. delbrueckii. Native T. delbrueckii showed a biocontrol action in the first two days of fermentation (wild yeasts reduced by c.a. 1 log at the second day). Finally, trials with the combination of both native and commercial T. delbrueckii/S. cerevisiae led to distinctive aromatic profiles of wines, with a significant enhancement in isoamyl acetate, phenyl ethyl acetate, supported by positive appreciations from the tasters, for ripe and tropical fruits, citrus, and balance. The whole results indicate that native T. delbrueckii could be a potential biocontrol tool against wild yeasts in the first phase of fermentation, contributing to improving the final wine aroma.

Online monitoring of higher alcohols and esters throughout beer fermentation by commercial Saccharomyces cerevisiae and Saccharomyces pastorianus yeast.

Higher alcohols and esters are among the predominant classes of volatile organic compounds (VOCs) that influence the quality of beer. The concentrations of these compounds are determined through a specific yeast strain selection and fermentation conditions. The effect of yeast strains on the formation of higher alcohols and esters throughout fermentations (at 20°C) was investigated. Flavour-relevant esters (ethyl acetate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) and higher alcohols (isoamyl alcohol, isobutyl alcohol and phenylethyl alcohol) were monitored throughout the fermentation using proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) coupled with an automated sampling system for continuous measurements. Compound identification was confirmed by analysis of samples using gas chromatography-mass spectrometry (GC-MS). Results demonstrated the specific time points where variation in higher alcohol and ester generation between yeast strains occurred. In particular, the concentrations of isoamyl acetate, ethyl octanoate and isoamyl alcohol between yeast strains were significantly different over the first 2 days of fermentation; whereas, after Day 3, no significant differences were observed. The two Saccharomyces pastorianus strains produced comparable concentrations of the key higher alcohols and esters. However, the key higher alcohol and ester concentrations varied greatly between the two S.cerevisiae strains. The use of PTR-ToF-MS to rapidly measure multiple yeast strains provides new insights on fermentation for brewers to modify the sensory profile and optimise quality.

The Influence of Functional Materials on the Size of the Lipid Vesicles in Beverages

By investigating the hydrophobic properties and functional components including ethyl caproate (EC), caproic acid (CA), isoamyl acetate (IA), isoamyl alcohol (IAA), isovaleraldehyde (IVA), and procyanidin B2 (PB2) in beverages, one can incorporate them with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipids to create cell-sized lipid vesicles. The aim of this study was to explore the correlation between the concentration of flavors or functional compounds and the size of the lipid vesicles. It was observed that EC, CA, IA, and IAA decreased the size of lipid vesicles. In contrast, IVA and PB2 increased their size. To comprehend this correlation, both the chemical structure of these compounds in relation to DOPC membranes and the fluidity of the membranes were considered. The size of the lipid vesicles was influenced by the molecular interactions between the compounds and DOPC. Those were caused by, in particular, the balance between hydrophobicity and hydrophilicity. Compounds with higher hydrophobicity tended to decrease the size of the lipid vesicles, whereas compounds with greater hydrophilicity had the opposite effect, leading to an increase in size. These findings suggest that the size of lipid vesicles can serve as a potential indicator for rapidly evaluating the concentration of these components in beverages.

Influence of Native Saccharomyces cerevisiae Strains on Malvasia aromatica Wines.

In the search of tools to deal with climate change-related effects along with the aim of avoiding the loss of aromatic typicity in wine, two native yeasts strains of Saccharomyces cerevisiae (CLI 271 and CLI 889) were evaluated to determine their influence on white Malvasia aromatica wines aroma composition and sensory characteristics. The strains were tested versus a commercial yeast strain (LSA). The fermentations were performed on grape must of the Malvasia aromatica variety previously macerated. Wine quality was studied by analysis of oenological parameters together with volatile aroma components using gas chromatography coupled to flame ionization detector (GC-FID) to quantify major volatiles compounds and headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) to determine terpenoids and C13-norisoprenoids. Sensorial analysis was also realized by an experienced taster panel. Wines from locally-selected yeasts strains used had lower volatile acidity levels and higher concentration of aromatic compounds compared to the commercial strain ones. The yeast strain S. cerevisiae CLI 271 provided wines with a higher concentration of esters related to fruity attributes, especially isoamyl acetate. The tasting panel highlighted the strong floral character of wines from S. cerevisiae CLI 889 fermentation. The use of microorganisms well adapted to climatic conditions can be used to produce quality wines of the Malvasia aromatica variety.

A study on the volatile compounds in Japanese alcoholic beverage (Awamori) produced from Thai rice varieties

Awamori is a famous alcoholic beverage brewed in the Southern part of Japan. Thai rice is well known and there are many varieties of rice including white rice and pigmented rice. This research aimed to study the properties and volatile compounds of Awamori produced from five Thai rice varieties including KDML105, Chainat, RD6, brown KDML105, and riceberry rice. Rice koji was prepared by inoculating the steamed rice with tane-koji from Aspergillus awamori at 0.2% by weight. Then, water and Saccharomyces cerevisiae were added and alcoholic fermentations were performed at around 2 weeks. The production of alcohol and pH changes during the liquid fermentation were monitored, and volatile compounds of the Awamori were determined by gas chromatography-mass spectrophotometry (GC-MS). The highest soluble solid and alcohol content were observed in the fermentation of KDML 105. The alcohol content after 2 weeks of fermentation ranged from 14.5-18 %, with the pH around 4.02-4.5. The same volatile compounds, ethyl alcohol, isobutyl alcohol, isoamyl alcohol, phenylethyl alcohol, isoamyl acetate, ethyl laurate, ethyl linoleate, with the flavor descriptions as alcohol, wine-like, mushroom-like, floral, rose, fruity, banana, sweet, ice-cream, mild fatty, oily, and honey-like odors were detected in all samples from Thai rice while KDML105 presented greater diversity of volatile compounds than the other Thai rice.

Olfactory behavioral responses of two Drosophila species and their pupal parasitoid to volatiles from bananas.

Behavior-based manipulation is an essential part of Drosophila integrated pest management (IPM). Effective compounds are useful for improving the efficiency of baits and the development of attract-and-kill or push-pull strategies to manage Drosophila populations. Here, we investigated the olfactory behavior of two Drosophila species, as well as their pupal parasitoid, to volatiles from bananas, for the identification of effective compounds to control fly populations. The results showed that overripe bananas were most attractive to both flies, with a higher attraction index (AI) in Drosophila melanogaster than in Drosophila suzukii. The profiles of volatile organic compounds (VOCs) from bananas with three different ripening stages were compared, and six VOCs were selected for behavioral tests. D. suzukii showed significantly different responses to isoamyl alcohol with D. melanogaster. The effects of ethyl butyrate and ethyl isovalerate on the two flies were dose-dependent, with lower concentrations acting as repellent and higher concentrations acting as attractant. Isoamyl acetate, isoamyl butyrate and isoamyl isovalerate (0.005-0.05% v/v) were attractive to both flies. The parasitoid wasp Pachycrepoidus vindemmiae was repelled by isoamyl alcohol and ethyl butyrate, and attracted by ethyl isovalerate, but showed no significant response to isoamyl acetate, isoamyl butyrate and isoamyl isovalerate at the tested concentration. This study indicated that the behavioral response of Drosophila to the odor of chemical compounds is dose-dependent. Isoamyl alcohol and isoamyl acetate at certain concentrations could be used as repellents, whereas ethyl isovalerate as an attractant in control strategy design for D. suzukii. © 2023 Society of Chemical Industry.

Differences in Aroma Profile of Cabernet Sauvignon Grapes and Wines from Four Plots in Jieshi Mountain Region of Eastern China.

The Bohai Bay region is a famous wine-growing area in China, where the rainfall is concentrated in the summer due to the influence of the temperate semi-humid monsoon climate. As such, the vineyard terrain has a significant impact on the flavor quality of the grapes and the resulting wines. To explore the relationship between the 'Cabernet Sauvignon' wine style and terrain, this study takes four different plots in the Jieshi Mountain region to investigate the differences in the aroma profile of Cabernet Sauvignon grapes and wines of two consecutive vintages. Based on two-way ANOVA, there were 25 free and 8 glycosylated aroma compounds in the grapes and 21 and 10 aroma compounds with an odor activity value greater than 0.1 in the wines at the end of alcohol fermentation (AF) and malolactic fermentation (MLF), respectively, that varied among the four plots. Wines from the four plots showed a significant difference in floral and fruity aroma attributes, which were mainly related to esters with high odor activity values. The difference in concentration of these compounds between plots was more pronounced in 2021 than in 2020, and a similar result was shown on the Shannon-Wiener index, which represents wine aroma diversity. It has been suggested that high rainfall makes the plot effect more pronounced. Pearson's correlation analysis indicated that concentrations of (E)-3-hexen-1-ol in grapes and ethyl 3-methylbutanoate, ethyl hexanoate, isoamyl acetate, isopentanoic acid, and phenethyl acetate in wines were strongly positively correlated with the concentrations of N, P, K, Fe, and electrical conductivity in soil but negatively correlated with soil pH. This study laid a theoretical foundation for further improving the level of vineyard management and grape and wine quality in the Jieshi Mountain region.

The Production of Intensified Qu and Its Microbial Communities and Aroma Variation during the Fermentation of Huangjiu (Chinese Rice Wine).

In recent years, intensified Qu (IQ) has been gradually applied to brewing in order to improve the aroma of Huangjiu (Chinese rice wine). In this study, Saccharomyces cerevisiae and Wickerhamomyces anomalus solutions were added to Fengmi Qu (FMQ) from Fangxian, China to produce IQ, and brewing trial was conducted. High-throughput sequencing (HTS) was used to analyze the microbial community in fermentation broth of IQ (IQFB). Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were performed to analyze volatile aroma compounds (VACs) in sample without Qu and both fermentation broths. The results showed that Pediococcus, Cronobacter, Enterococcus, Weissella, and Acinetobacter and Saccharomycopsis, Wickerhamomyces, and Saccharomyces were dominant bacterial and fungal groups, respectively. A total of 115 VACs were detected, and the content of esters including ethyl acetate, isoamyl acetate, and so on was noticeably higher in IQFB. The finding of sensory evaluation reflected that adding pure yeast to Qu could enhance fruit and floral aromas. Correlation analysis yielded 858 correlations between significant microorganisms and different VACs. In addition, prediction of microbial community functions in IQFB revealed global and overview maps and carbohydrate metabolism to be the main one. This study is advantageous for further regulation of the fermentation process of Huangjiu by microbial means.

Mosaic Genome of a British Cider Yeast.

Hybrid formation and introgressions had a profound impact on fermentative yeasts domesticated for beer, wine and cider fermentations. Here we provide a comparative genomic analysis of a British cider yeast isolate (E1) and characterize its fermentation properties. E1 has a Saccharomyces uvarum genome into which ~102 kb of S. eubayanus DNA were introgressed that replaced the endogenous homologous 55 genes of chromosome XIV between YNL182C and YNL239W. Sequence analyses indicated that the DNA donor was either a lager yeast or a yet unidentified S. eubayanus ancestor. Interestingly, a second introgression event added ~66 kb of DNA from Torulaspora microellipsoides to the left telomere of SuCHRX. This region bears high similarity with the previously described region C introgression in the wine yeast EC1118. Within this region FOT1 and FOT2 encode two oligopeptide transporters that promote improved nitrogen uptake from grape must in E1, as was reported for EC1118. Comparative laboratory scale grape must fermentations between the E1 and EC1118 indicated beneficial traits of faster consumption of total sugars and higher glycerol production but low acetic acid and reduced ethanol content. Importantly, the cider yeast strain produced high levels of fruity ester, including phenylethyl and isoamyl acetate.

Cinnamon essential oil vapor alleviates the reduction of aroma-related volatiles in cold-stored "Feicheng" peach using HS-GC-IMS.

"Feicheng" peach is popular for its unique aroma, but its defect of being highly sensitive to chilling injury (CI) often leads to aroma loss and internal browning. Essential oils (EOs) are often used to enhance the antioxidant capacity of plants and fruits, as well as to trigger their defense against biotic/abiotic stresses. This study aimed to examine the effect of cinnamon essential oil (CEO) vapor treatment on the aroma quality of peach fruit during cold storage using HS-GC-IMS. The results showed that 50 μL/L CEO vapor reduced the severity of internal browning (IB) in peaches at the stage of 7 ~ 21 d during refrigeration (Significantly, the L* value was higher and the IB index was lower than that of control, p < 0.05). Meanwhile, the evident reduction or loss of aroma content caused by CI was restored to a higher level than the control (p < 0.05). Furthermore, CEO treatment promoted the release of aroma-related volatiles as evidenced by more propyl acetate, and the dimer of amyl acetate, isoamyl acetate, butyl acetate detected than that on harvest day and no-treated group after 21 d of cold storage plus 2 d of shelf life. Genes of PpLOX1, PpLOX2, PpHPL1 and PpADH1 associated with aroma-related volatile biosynthesis revealed higher transcript abundance in peach fruits treated with CEO than the control (p < 0.05). Overall, our study demonstrated that CEO in vapor phase may be beneficial to alleviate the quality deterioration in aroma and flesh color of "Feicheng" peaches caused by CI, which lays a theoretical reference for maintaining postharvest quality of peach fruits.