Aroma compounds and characteristics of noble-rot wines of Chardonnay grapes artificially botrytized in the vineyard

Selection of indigenous Saccharomyces cerevisiae strains with good oenological and aroma characteristics for winemaking in Ningxia China

Ningxia is one of the well-known wine producing regions in China. However, the oenological and aroma characteristics of indigenous yeasts remains hidden. The fermentative and oenological properties including stress resistance, hydrogen sulfide, foam production levels; killer phenotype, and flocculation of 89 Ningxia indigenous Saccharomyces cerevisiae isolates and ten commercial yeasts were evaluated. The fermentative and oenological properties of the tested strains varied significantly. They could resist 500 g/L glucose, 300 mg/L SO2, 14% (v/v) ethanol and pH 2.8, and produce more esters. They also produce low levels of ethanol and could conduct fermentations vigorously and at a high rate. Cabernet Sauvignon wines made with NXU 21-24 showed the high intensity of tropical fruit, dry fruit, temperate fruit, and spicy flavor. The floral flavor in NXU 21-102 fermented wine is very intense. The indigenous S. cerevisiae strains of NXU 21-102 and NXU 21-24 exhibited potential use as starter cultures in wine production.

Volatile aroma compound-based decoding and prediction of sweet berry aromas in dry red wine

To explore the volatile markers of typical sweet berry flavors in dry red wine, Marselan, Cabernet Sauvignon, Merlot, and Cabernet Franc wines were pretreated using solid-phase microextraction (SPME) and liquid-liquid extraction-solvent-assisted flavor evaporation (LLE-SAFE), and key odorants were analyzed using sensomics approach. Results indicated that Marselan wines exhibited intense sweet berry aromas compared to other varieties wines. Omission tests on one- and four-year-aged wines identified β-damascenone, isoamyl acetate, 2,3-butanediol, phenylethanol as sweet aroma markers, while geranyl acetone, ethyl isobutyrate, ethyl 2-methylbutyrate as berry aroma markers, which were verified by partial least squares regression. Meanwhile, optimal flavor intensity prediction models between sweet/berry aroma and volatile markers natural logarithms concentration were created with all wines. Moreover, consistent with aroma intensity, most berry markers content increased during aging while sweet markers decreased. This study completes the analytical methodology for volatile markers of wine typical aroma and provides theoretical support for wine flavor prediction.

Wine Volatilome as Affected by Tartaric Stabilization Treatments: Cold Stabilization, Carboxymethylcellulose and Metatartaric Acid

The primary cause of bottled wine sediment is tartrate crystal precipitation. To prevent this, wines undergo a stabilization process before bottling. The most commonly used method is cold stabilization, which induces the precipitation of tartrate crystals that are then removed, thereby eliminating the excess ions that cause instability in wine. Another approach to tartaric stabilization is using enological stabilizers with a colloid protective effect, which prevents the formation of tartrate crystals. The most commonly used tartaric stabilizers are sodium carboxymethylcellulose (CMC) and metatartaric acid. However, both have drawbacks: they are semi-synthetic products, and metatartaric acid degrades over time, losing its stabilizing effect. This study aims to compare the effects of cold stabilization, stabilization with CMC, and metatartaric acid on the chemical composition, particularly the volatilome, of white, rosé, and red wines. Cold stabilization significantly impacted the wine volatilome, especially in white and rosé wines, by decreasing total alcohols and increasing total esters. It also reduced the color intensity of rosé and red wines by lowering monomeric anthocyanins. In contrast, enological stabilizers had minimal impact on the wines' phenolic composition, chromatic characteristics, and volatilome. The sensory impact of cold stabilization is complex; it can potentially enhance the aroma of white and rosé wines by increasing ester VOCs and decreasing higher alcohols, but it negatively affects the color of rosé and red wines.

Enhancing the flavour quality of Laiyang pear wine by screening sorbitol-utilizing yeasts and co-fermentation strategies

This study took a novel approach to address the dual challenges of enhancing the ethanol content and aroma complexity in Laiyang pear wine. It focused on sorbitol as a pivotal element in the strategic selection of yeasts with specific sorbitol-utilization capabilities and their application in co-fermentation strategies. We selected two Saccharomyces cerevisiae strains (coded as Sc1, Sc2), two Metschnikowia pulcherrima (coded as Mp1, Mp2), and one Pichia terricola (coded as Tp) due to their efficacy as starter cultures. Notably, the Sc2 strain, alone or with Mp2, significantly increased the ethanol content (30% and 16%). Mixed Saccharomyces cerevisiae and Pichia terricola fermentation improved the ester profiles and beta-damascenone levels (maximum of 150%), while Metschnikowia pulcherrima addition enriched the phenethyl alcohol content (maximum of 330%), diversifying the aroma. This study investigated the efficacy of strategic yeast selection based on sorbitol utilization and co-fermentation methods in enhancing Laiyang pear wine quality and aroma.

Impact of pre- and post-fermentation fining with polyvinylpolypyrrolidone on the chemical stability and aromatic profile of Viognier wine

Polyvinylpolypyrrolidone (PVPP) is a synthetic, insoluble polymer that can be added to white wines to improve the chemical stability of the final product by precipitating unstable low molecular weight phenolic compounds responsible for visual defects and undesirable flavor characteristics (e.g., excessive bitterness and/or astringency). The objective of this study was to characterize the effects of PVPP on the quality characteristics of Viognier wine when added pre- or post-fermentation as compared to an untreated control wine. Both PVPP-treated wines contained significantly lower concentrations of monomeric phenolics and browning pigments than the control wine (p ≤ 0.05). The addition of PVPP prior to fermentation conferred protection against oxidation of the wine as measured by acetaldehyde concentration (p ≤ 0.05). Analysis of the volatile aroma profile of each wine by headspace solid phase microextraction gas chromatographymass spectrometry (HS-SPME-GC-MS) revealed that the overarching aroma profiles of the PVPP-treated wines were significantly different from the control wine, but there was no difference between wines treated with PVPP pre-fermentation versus those treated post-fermentation. Specifically, statistically significant differences were observed in 9 of the 22 quantified aroma compounds, including those notably associated with the "stone fruit" aroma of Viognier. A negative correlation was identified between aroma compound concentration removal and the hydrophobicity of each compound, suggesting that the observed differences in aroma may be due to adsorption of aroma compounds by PVPP. The findings from this study present risks and benefits to wine quality upon treatment with PVPP at commercially recommended levels, and provide potentially valuable information for industrial wine producers.

Site-Directed Mutagenesis of VvCYP76F14 (Cytochrome P450) Unveils Its Potential for Selection in Wine Grape Varieties Linked to the Development of Wine Bouquet

Bouquet is a fascinating wine characteristic that serves as an indicator of wine quality, developing during the aging process. The multifunctional monoterpenol oxidase VvCYP76F14 in wine grapes sequentially catalyzes three reactions to produce (E)-8-carboxylinalool, a crucial precursor for wine bouquet. Previous studies indicated that the activity of VvCYP76F14 derived from different wine grape varieties did not correlate with the amino acid sequence differences. In this study, 54 wine grape varieties were categorized into neutral, aromatic, and full-bodied types based on the sequence differences of VvCYP76F14, closely correlated with the content of wine lactone precursors. Computer modeling and molecular docking analysis of the full-bodied CYP76F14 revealed 17, 19, and 18 amino acid residues in the VvCYP76F14-linalool, VvCYP76F14-(E)-8-hydroxylinalool, and VvCYP76F14-(E)-8-oxolinalool complexes, respectively. Site-directed mutagenesis and in vitro enzyme activity analysis confirmed the substitutions of the key amino acid residues in neutral and aromatic varieties. Notably, the D299 mutation of VvCYP76F14 resulted in the complete loss of (E)-8-oxolinalool and (E)-8-carboxylinalool activities, aligning with the undetectable levels of (E)-8-oxolinalool and (E)-8-carboxylinalool in "Yantai 2-3-37", which harbors the D299T substitution. Favorably, VvCYP76F14 could serve as a cost-effective fingerprint marker for screening superior hybrid offspring with the desired levels of wine lactone precursors.

Adjusting the pomace ratio during red wine fermentation: Effects of adding white grape pomace and juice runoff on wine flavoromics and sensory qualities

Adding pomace or juice runoff during maceration is a traditional winemaking process. To mitigate the negative effects of rainfall during harvest and examine the effects of adjusting the pomace ratio during fermentation on the flavor profile of Marselan grape wines, the prefermentation addition of Petit Manseng grape pomace (PAP) and prefermentation juice runoff (PJR) was determined. The phenolic and volatile compounds were investigated using HPLC-MS and GC-MS. PAP enriched the flavanols and PJR enriched the pigment and copigment matrix. Approximate 10% increase in the ratio of pomace promoted the formation of anthocyanin derivatives. The increased pomace ratio reduced the concentration of volatile compounds without impacting the aroma quality. Sensory analysis revealed PAP wines scored higher for acidity and astringency and PJR wines scored higher for color. In conclusion, an appropriate increase in the pomace ratio of approximately 10% can enhance the color and mouthfeel of the wine while having a limited influence on aroma.

Isolation and Identification of Lactic Acid Bacteria and Their Effects on the Off-odor of Burdocks

Burdocks have diverse nutritional and pharmacological functions, but their unique odor is unwelcome. Here, the effect and mechanism of lactic acid bacteria fermentation on the off-odor of burdocks were investigated. The sensory evaluation showed that burdocks had earthy, musty, grassy, and pepper odors. 2-Isobutyl-3-methoxypyrazine (IBMP) and 2-secbutyl-3-methoxypyrazine (IPMP) mainly contributed to burdock's unique off-odor and were identified by gas chromatography-mass spectrometry combined with headspace-solid phase microextraction (HS-SPME-GC-MS) and relative odor activity value (ROAV) analysis. Weissella cibaria ZJ-5 from screened strains performed with the strongest ability to remove the off-odor and generate a fragrant odor, as determined by sensory evaluation. When incubated aerobically together with IBMP during fermentation, ZJ-5 degraded IBMP directly from 149.56 ± 0.72 to 71.55 ± 1.81 ng/mL. Additionally, linoleic acid content in fermented burdocks was significantly decreased compared with unfermented burdocks. (E,Z)-2,6-Nonadienal, which mainly contributed to fermented burdock's odor, may have been generated from linoleic acid during ZJ-5 fermentation, through the acid catalysis pathway. It indicated that LAB fermentation could improve burdock odor by degrading off-odor compounds and precursors and by generating new aldehydes.

Ras2 Is Responsible for the Environmental Responses, Melanin Metabolism, and Virulence of Botrytis cinerea

Ras proteins are monomeric G proteins that are ubiquitous in fungal cells and play important roles in fungal growth, virulence, and environmental responses. Botrytis cinerea is a phytopathogenic fungus that infects various crops. However, under specific environmental conditions, the overripe grapes infected by B. cinerea can be used to brew valuable noble rot wine. As a Ras protein, the role of Bcras2 in the environmental responses of B. cinerea is poorly understood. In this study, we deleted the Bcras2 gene using homologous recombination and examined its functions. Downstream genes regulated by Bcras2 were explored using RNA sequencing transcriptomics. It was found that ΔBcras2 deletion mutants showed significantly reduced growth rate, increased sclerotia production, decreased resistance to oxidative stress, and enhanced resistance to cell wall stress. Additionally, Bcras2 deletion promoted the expression of melanin-related genes in sclerotia and decreased the expression of melanin-related genes in conidia. The above results indicate that Bcras2 positively regulates growth, oxidative stress resistance, and conidial melanin-related genes expression, and negatively regulates sclerotia production, cell wall stress resistance and sclerotial melanin-related genes expression. These results revealed previously unknown functions of Bcras2 in environmental responses and melanin metabolism in B. cinerea.

Use of Mixed Cultures for the Production of Grape–Plum Low-Alcohol Fermented Beverages

This work presents the attempt to develop a production technology for grape–plum low-alcohol beverages and enhance their chemical composition and flavor complexity through the non-Saccharomyces species. Saccharomyces cerevisiae (SC) pure cultures were used as reference beverages. Pure cultures of Lachancea thermotolerans (LT) and co-inoculated Lachancea thermotolerans with Saccharomyces cerevisiae (MIX) were included for grape–plum must fermentation at a pilot scale. The process involves two steps: a primary alcoholic fermentation in stainless steel tanks (F1) and a secondary fermentation in a bottle after dextrose syrup addition (F2). The chemical compositions of all beverages obtained in F1 and F2 were studied. Compared to SC, must inoculated with L. thermotolerans (LT and MIX) required four more days to complete the fermentation of sugars during F1. SC fermentation tended to have slightly higher pH and titratable acidity values and lower concentrations of total phenols. Final levels of aromatic precursor nitrogen and sulfur amino nitrogen were obtained more in SC than in LT and MIX. SC treatment had higher final levels of histidine, phenylalanine, isoleucine, lysine, methionine, threonine, valine, and cysteine. Related to individual amino acids, SC treatment had higher final levels of histidine, phenylalanine, isoleucine, lysine, methionine, threonine, valine, and cysteine. Analysis of the volatile composition showed that, compared with SC, MIX had the highest percentage of higher alcohols (3-methyl-1-butanol and 2-methyl-1-butanol) and acetates (isoamyl acetate and isobutyl acetate) which are associated with fruity and banana aromas. A decreasing trend in volatile fatty acids was observed in LT and MIX compared to SC. LT application, both in pure and mixed culture, significantly modified the values of the percentage of 5 of the 10 ethyl ester compounds analyzed. Finally, the sensory analysis showed that there were no significant differences, even though the non-Saccharomyces had a higher percentage of volatile metabolites. The results have shown that through this process an innovative and high-quality product was obtained: a low-alcohol beverage made from grapes and plums, which could be developed at an industrial level due to the increasing interest of consumers in this type of product.

Saturated Linear Aliphatic γ- and δ-Lactones in Wine: A Review

Saturated linear aliphatic lactones are widespread aroma compounds in wine, linked to stone fruit, dried red fruit, and coconut descriptors. Despite their ubiquity, bioproduction pathways associated with these compounds in wine are unclear, but higher concentrations have been linked to many common vitivinicultural practices, including grape variety, microbiological influence, oak- and bottle-aging, and wine styles such as late harvest, noble rot, and icewine. Development of analytical techniques has enabled increasingly accurate quantification of lactones in wine, shedding more light on their potential origins. This review provides an in-depth summary of the research into linear aliphatic lactones over the past 50 years and provides direction for possible future research to elucidate the biogenesis of these compounds and better estimate their impact on wine aroma.

A Sustainable Approach Based on the Use of Unripe Grape Frozen Musts to Modulate Wine Characteristics as a Proof of Concept

Aiming to develop a sustainable methodology for must acidity correction in winemaking, particularly needed in warm regions, the present study intends to fulfill the circular economy values. Antão Vaz white wines were produced using two different strategies for must acidity correction: (i) the addition of a mixture of organic acids (Mix*) commonly used in winemaking; and (ii) the addition of previously produced unripe grape must (UM*) from the same grape variety. In addition, a testimonial (T*) sample was produced with no acidity correction. For all wines produced, oenological parameters were determined, and both amino acid (AA) content and volatile composition were evaluated. A higher AA content was found in the Antão Vaz T* wine, followed by UM* wines. The volatile profile was also affected, and LDA demonstrates a clear separation of wines with different acidity corrections. Results obtained indicate that unripe grape musts—a vital waste product containing several compounds with important biological activity—can be used to increase musts acidity without a negative impact on wine characteristics. Furthermore, this work also shows that the use of unripe must may be a valuable tool for reducing the alcoholic content of wines.

The effect of ultrasound on Syrah wine composition as affected by the ripening or sanitary status of the grapes

Several studies have demonstrated that the application of ultrasounds to crushed grapes improves the chromatic and sensory characteristics of the resulting wines by facilitating the extractability of compounds from grapes to the must-wine. The objective of this work was to determine whether the application of ultrasounds to grapes of different maturity levels or different sanitary status leads to the same positive outcome as regards chromatic characteristics, phenolic and aroma compounds as well as sensory properties. The results showed that, independent of grape ripening or sanitary status, the application of ultrasounds to Syrah crushed grapes leads to wines with better chromatic characteristics at the moment of bottling, increasing colour intensity, total phenol content and tannin concentration up to 12%, 18% and 43%, respectively, in the wines from less ripen grapes and 13%, 23% and 30% in the wine from partially rotten grapes. The concentration of volatile compounds was less affected by sonication than the chromatic characteristics, with small decreases in the main families of volatile compounds, although the sensory analysis showed clear differences between control wines and those made from sonicated grapes, which were generally preferred and score higher for most of the sensory parameters evaluated.

The Expression of Aroma Components and Related Genes in Merlot and Marselan Scion-Rootstock Grape and Wine

Rootstocks were bred and selected from several species in order to enhance the resistance against biotic or abiotic stresses. There are few studies on the effect of rootstocks on aroma and related gene expression. This study focused on the effects of three rootstocks, Kober 5BB (5BB), 1103 Paulsen (1103P), and Selection Oppenheim (SO4), on the aroma and volatile-related gene expression levels of Merlot and Marselan berries and wines. These three rootstocks reduced the total aroma content of Merlot wine. 5BB upregulated VvLoXA and showed increased C6 alcohols. 1103P enhanced the linalool from Merlot berry, with marked upregulation of VvLinNer1. Conversely, rootstocks increased the total aroma content of Marselan berry, verified by the related expression levels of volatile-related genes. For Marselan berry, 5BB and 1103P upregulated five VvGTs and nine genes from the LOX and MEP pathway. 1103P increased the contents of C6 alcohols, C6 aldehydes, and citronellol from Marselan berry. Compared to 5BB and SO4, rootstock 1103P provided berries of better quality and richer aroma volatiles to Merlot and Marselan, while all three of the rootstocks had a significant effect on scion–rootstocks.

Volatile profile of two monovarietal white wines under different antioxidant environments during storage in bottle

The volatile organic compounds (VOCs) formed during winemaking can be modulated by several additives, namely by the use of sulphur dioxide (SO2) which has been well-accepted on winemaking as a preservative agent. However, some drawbacks associated with SO2 wine application led to the need to reduce or replace its use. In this work, VOCs profile after storage in bottle under different antioxidant conditions of two Portuguese monovarietal wines (‘Arinto’ and ‘Síria’) was studied. Wines were obtained by different winemaking environments (0, 50, 100 mg/L of SO2 and 100 mg/L ascorbic acid for ‘Síria’ and 15, 30, 45 mg/L of SO2 and 100 mg/L of ascorbic acid for ‘Arinto’ both with and without bentonite). After alcoholic fermentation, a second SO2 treatment was applied: 0 and 60 mg/L of SO2 to ‘Arinto’ wines and 30 and 60 mg/L of SO2 to ‘Síria’ wines. Wines were kept over lees for three months, bottled and analysed after three months in bottle. The VOCs present were analysed by HS-SPME-GC/MS six months after fermentation. The maturation conditions did not influence the evolution of free and total SO2. Regarding the VOCs profile evolution, the ANOVA analysis showed that esters are the most important group, presenting significant differences among samples. Through the PCA analysis, using wines after fermentation as reference, 74.13 % and 54.92 % of the variation were explained by the first two principal components for ‘Arinto’ and ‘Síria’, respectively. VOCs profile evolution of wines seems to be mainly influenced by the fermentation conditions.

Lactic acid bacteria synergistic fermentation affects the flavor and texture of bread

Fermentation strains play a key role in the quality of bread. The combination of yeast and lactic acid bacteria (LAB) may effectively improve the function and nutritional properties of bread. In this study, the dough was fermented to make bread by using single strain (Saccharomyces cerevisiae, mode A), the combination of two strains (S. cerevisiae and Lactiplantibacillus plantarum, mode B; S. cerevisiae and Lactobacillus delbrueckii, mode C), or three strains (S. cerevisiae, L. plantarum, and L. delbrueckii, mode D). The specific volume, texture, and aroma substances of bread were evaluated. The possibility of mixed fermentation of selected yeast and LAB to replace natural fermentation dough was evaluated. The results showed that the specific volume of bread in mode B was 15.2% higher than that of mode A. The structure was softer and the taste was more vigorous in mode B bread. The content of volatile compounds was highest in mode B bread among the four mode bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol. The cofermentation in mode B made the bread aroma richer and gave better aroma characteristics to bread. Therefore, the fermentation of S. cerevisiae and L. plantarum can be recommended to replace naturally fermented dough to improve the quality of bread. PRACTICAL APPLICATION: L. plantarum and L. delbrueckii, separately or together, assisted in yeast fermentation to make bread. The specific volume, texture, and aroma substances of bread were evaluated to replace natural fermented dough with mixed fermentation. L. plantarum-assisted yeast fermentation improved the specific volume, texture, and aroma of bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol in bread. Therefore, the fermentation of S. cerevisiae and L. plantarum could replace naturally fermented dough to improve the quality of bread.

Pre-Fermentative Cold Maceration and Native Non-Saccharomyces Yeasts as a Tool to Enhance Aroma and Sensory Attributes of Chardonnay Wine

The oenological potential of native strains of Metschnikowia pulcherrima B-5 and Candida famata WB-1, isolated from blackberries, was investigated in pure and sequential fermentation of Chardonnay grape with commercial Saccharomyces cerevisiae QA23. The effect of pre-fermentative cold maceration was also analysed. The fermentations were performed in the pilot-scale trials and the profile of volatile compounds and their sensory characteristics were determined. The application of C. famata WB-1 and M. pulcherrima B-5 reduced the volatile acidity and increased total polyphenols of the wines, compared to the control samples. Higher alcohols and esters were dominant, while fatty acids and aldehydes and ketones were also detected. Esters had the greatest contribution to sensory characteristics, especially the development of floral and fruity aromas. Most esters were present in lower concentrations in sequential fermentations compared to the pure fermentations with M. pulcherrima B-5 or C. famata WB-1. Pre-fermentative maceration positively affected both the aroma and the sensory profile. The best sensory score was determined for wines produced using C. famata WB-1 in the fermentations without pre-fermentative maceration, and the sequential fermentation of M. pulcherrima B-5 with maceration. Native strains of M. pulcherrima B-5 and C. famata WB-1 have shown great potential for the enhancement of the aromatic and sensory profile of Chardonnay wine.

Assessment of chemical constitution and aroma properties of kiwi wines obtained from pure and mixed fermentation with Wickerhamomyces anomalus and Saccharomyces cerevisiae

BACKGROUND

To improve the aroma of kiwi wine through the utilization of Wickerhamomyces anomalus, kiwi juice was fermented using a selected W. anomalus strain in pure culture and mixed fermentations with Saccharomyces cerevisiae, which was inoculated simultaneously and sequentially. The physicochemical indices, volatile compounds and aroma properties of the kiwi wines were assessed.

RESULTS

The study suggested that the ethanol, color indices and organic acids of the wines were closely related to the method of inoculation. Compared with the pure S. cerevisiae fermentation, the mixed fermentations produced more varieties and concentrations of volatiles. The sequential fermentations increased the concentrations of esters and terpenes, improving the flower and sweet fruit notes of the wines. The simultaneous inoculation enhanced the contents of esters and aldehydes, intensifying the flower, sweet and sour fruit of the wines. Partial least-squares regression analysis showed that esters and terpenes contributed greatly to the flower and sweet fruit aroma, whereas aldehydes were the major contributors to the sour note.

CONCLUSION

Based on our results, the mixed fermentations not only enriched the types and concentrations of volatiles, but also had better sensory properties. © 2021 Society of Chemical Industry.

Volatile Metabolism of Wine Grape Trincadeira: Impact of Infection with Botrytis cinerea

The aroma of grapes is cultivar dependent and is influenced by terroir, vineyard practices, and abiotic and biotic stresses. Trincadeira is a non-aromatic variety associated with low phenolic content and high sugar and organic acid levels. This cultivar, widely used in Portuguese wines, presents high susceptibility to Botrytis cinerea. This work aimed to characterise the volatile profile of Trincadeira grapes and how it changes under infection with B. cinerea. Thirty-six volatile organic compounds were identified, from different functional groups, namely alcohols, ester acetates, fatty acid esters, fatty acids, aldehydes, and products of the lipoxygenase pathway. Both free and glycosidic volatile organic compounds were analysed by Gas Chromatography and Gas Chromatography coupled to Mass Spectrometry for component quantification and identification, respectively. A multivariance analysis showed a clear discrimination between healthy and infected grapes with 2-trans-hexenal and isoamyl-acetate among the compounds identified as negative and positive markers of infection, respectively. Ester acetates such as 2-phenylethyl acetate, isoamyl acetate, and 2-methylbutyl acetate were present in higher contents in infected samples, whereas the contents of several fatty acid esters, such as ethyl decanoate and ethyl dodecanoate, decreased. These data were integrated with quantitative PCR data regarding genes involved in volatile metabolism and showed up-regulation of a gene coding for Hydroperoxide Lyase 2 in infected grapes. Altogether, these changes in volatile metabolism indicate an impact on the grape quality and may be related to defence against B. cinerea. The presence/absence of specific compounds might be used as infection biomarkers in the assessment of Trincadeira grapes' quality.

Classification of Botrytized Wines Based on Producing Technology Using Flow-Modulated Comprehensive Two-Dimensional Gas Chromatography

The enantiomeric ratio of chiral compounds is known as a useful tool to estimate wine quality as well as observe an influence of wine-producing technology. The incorporation of flow-modulated comprehensive two-dimensional gas chromatography in this type of analysis provides a possibility to improve the quality of results due to the enhancement of separation capacity and resolution. In this study, flow-modulated comprehensive two-dimensional gas chromatography was incorporated in enantioselective analysis to determine the influence of winemaking technology on specific features of botrytized wines. The samples included Tokaj essences (high-sugar wines), Tokaj botrytized wines and varietal wines (Furmint, Muscat Lunel, Lipovina) and wines maturated on grape peels. The obtained data was processed with hierarchic cluster analysis to reveal variations in composition and assess classification ability for botrytized wines. A significant difference between the samples was observed for the enantiomeric distribution of ethyl lactate and presence of monoterpene alcohols. The varietal wines were successfully separated from the other types, which showed more similar results and could be divided with additional parameters. We observed a correlation between the botrytized wines and the varietal wines fermented with grape skins. As to the essences produced from juice of botrytized grapes, the results were quite similar to those of the botrytized wines, even though monoterpenes were not detected in the extracts.

Effect of foliar application of fulvic acid antitranspirant on sugar accumulation, phenolic profiles and aroma qualities of Cabernet Sauvignon and Riesling grapes and wines

This study investigated the effects of foliar application of fulvic acid antitranspirant (FA-AT) on Cabernet Sauvignon (CS) and Riesling grapes and wines in a warm viticulture region of China. FA-AT controlled the contents of total soluble solids, fructose and glucose in mature grapes and alcohol in wines. FA-AT improved total phenols and flavonoids in Riesling grapes, and total tannin and individual flavanols in CS grapes and wine, while reducing total individual phenolic acids and flavonols in CS wine. Increased volatiles in CS grapes (hexyl acetate, linalool) and wine (isoamyl alcohol, 1-hexanol, 2-phenylethanol) detected by SPME-GC-MS can contribute to the fruity and floral aroma. FA-AT reduced the accumulation of anthocyanins in CS grapes and wine without an eventual reduction in the tonality of wine by sensory analysis, and improved the taste and balance of Riesling wine. Overall, FA-AT can improve the quality of grapes and wines produced in warm viticulture regions.

Effects of simultaneous and sequential cofermentation of Wickerhamomyces anomalus and Saccharomyces cerevisiae on physicochemical and flavor properties of rice wine

Microorganism species and inoculation fermentation methods have great influence on physicochemical and flavor properties of rice wine. Thus, this work investigated microbial interactions and physicochemical and aroma changes of rice wine through different inoculation strategies of Wickerhamomyces anomalus (W. anomalus) and Saccharomyces cerevisiae (S. cerevisiae). The results underlined that inoculation strategies and non-Saccharomyces yeasts all affected the volatile acidity, total acidity, and alcohol content of rice wine. The sequential cofermentation consumed relatively more sugar and resulted in the higher ethanol content, causing reduced thiols and increased alcohols, esters, phenylethyls, and terpenes, which was more conducive to improve rice wine flavor than simultaneous cofermentation. Moreover, simultaneous cofermentation increased fatty aroma of rice wine, while sequential cofermentation increased mellow and cereal-like flavor. These results confirmed that sequential cofermentation of S. cerevisiae and W. anomalus was a choice for the future production of rice wine with good flavor and quality.

Sensory-directed characterisation of distinctive aromas of Sauternes and Viognier wines through semi-preparative liquid chromatography and gas chromatography approaches

Gas chromatography-olfactometry-mass spectrometry (GC-O-MS) has been very useful in identifying aroma compounds from within the complex matrix of wine. Supplementary separation can be required to overcome co-elution of volatiles or other sensory-directed chromatographic strategies are needed, including multidimensional chromatography and preparative fraction collection coupled to GC. Studies investigating 'overripe orange' aroma in sweet Sauternes wine and the similar 'apricot' aroma in Viognier wine were conducted. Wines with the targeted aroma attributes were selected and concentrated wine extracts prepared. GC-O found no individual aroma compounds with the targeted aroma attribute. Semi-preparative HPLC was used to obtain less complex fractions of the wine extracts. The fractions were eluted in water/ethanol and, therefore, could be smelled directly. Fractions with the targeted aroma character were further resolved by GC-preparative fraction collection (GC-PFC). Recombinational GC-PFC demonstrated the importance of the components within a 4 min preparative GC fraction to the 'overripe orange' aroma of typical Bordeaux dessert wine. In Viognier wine, monoterpenes linalool, α-terpineol and geraniol as well as benzaldehyde were found to be associated with the 'apricot' character. Thus, several wine aroma compounds interact for these specific aromas to be perceived. This sensory-led combination of separation techniques is a powerful tool for the identification of key compounds responsible for specific aromas across the wine and beverage industries.

Phenolic matrix effect on aroma formation of terpenes during simulated wine fermentation - Part I: Phenolic acids

In this study, fermentations were performed using simulated grape juice supplemented with terpene glycosides (TGs), extracted from Vitis vinifera L. Meili, and phenolic acids (gallic acid or p-coumaric acid). Free terpenes were detected using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) every day during the fermentation, and the aromas of final wines were evaluated by panelists. Quantum mechanical (QM) calculations performed at density functional level of theory were used to uncover the structural and thermodynamic properties of the binding between phenolic acids and free terpenes (or TGs). Results showed that phenolic acids remarkably inhibited TG hydrolysis and free terpene volatilization, and affected wine aroma perception. QM calculations revealed that phenolic acids can bind to linalool and its glycoside spontaneously (ΔG < 0) via hydrogen bonding and dispersive forces. These findings indicate that the matrix effect of phenolic acids can effectively control the release and modulate the global feature of wine aromas.

An overview on botrytized wines

Noble rot wine is a specific type of sweet wine that derives from the infection of grape berries by a fungus called Botrytis cinerea. These wines are produced in specific wine regions around the world, with Sauternes region of France and Tokay region of Hungary being the most famous ones. The purpose of the current article is to provide a systematic review on the different stages of botrytized wines production, including a detailed analysis of the technical aspects involved. Specifically, it describes the process and development of berry infection by B. cinerea, and special emphasis is given to the main stages and operations of winemaking, conservation, aging and stabilization. A complex combination of a number of parameters (e.g., very specific environmental conditions) explains the rarity of noble rot occurrence and highlights the uniqueness of botrytized wines.

Aromatic Characterization of New White Wine Varieties Made from Monastrell Grapes Grown in South-Eastern Spain

The aromatic profile of a wine is one of the main characteristics appreciated by consumers. Due to climate change, vineyards need to adapt to new conditions, and one of the strategies that might be followed is to develop new white varieties from Monastrell and other cultivars by means of intervarietal crosses, since white varieties are a minority in south-eastern Spain. Such crosses have already been obtained and have been seen to provide quality white wines of high acidity and with a good aromatic composition. To confirm this, a quantitative analysis was carried out during two vintages (2018 and 2019) in order to study and compare the volatile composition of Verdejo (V) wine with the aromatic composition of several wines made from different crosses between Cabernet Sauvignon (C), Syrah (S), Tempranillo (T), and Verdejo (V) with Monastrell (M), by means of headspace SPME-GC-MS analysis. Wine volatile compounds (alcohols, volatile acids, ethyl esters, terpenes, norisoprenoids, and two other compounds belonging to a miscellaneous group) were identified and quantified using a HS-SPME-GS-MS methodology. An additional sensory analysis was carried out by a qualified tasting panel in order to characterize the different wines. The results highlighted how the crosses MT103, MC69, and MC180 showed significant differences from and better quality than the Verdejo wine. These crosses produced higher concentrations of several aromatic families analyzed, which was supported by the views of the tasting panel, thus confirming their excellent aromatic potential as cultivars for producing grapes well adapted to this area for making white wines.

Effects of Crude β-Glucosidases from Issatchenkia terricola, Pichia kudriavzevii, Metschnikowia pulcherrima on the Flavor Complexity and Characteristics of Wines

To investigate the effects of crude β-glucosidases from Issatchenkia terricola SLY-4 (SLY-4E), Pichia kudriavzevii F2-24 (F2-24E), and Metschnikowia pulcherrima HX-13 (HX-13E) on flavor complexity and characteristics of wines, grape juice was fermented by Saccharomyces cerevisiae with the addition of SLY-4E, F2-24E and HX-13E, respectively. The growth and sugar consumption kinetics of S. cerevisiae, the physicochemical characteristics, the volatile compounds, and the sensory dimensions of wines were analyzed. Results showed that adding SLY-4E, F2-24E, and HX-13E into must had no negative effect on the fermentation and physicochemical characteristics of wines, but increased the content of terpenes, esters, and fatty acids, while decreased the C₆ compound content. Each wine had its typical volatile compound profiles. Adding SLY-4E or F2-24E into must could significantly improve the flavor complexity and characteristics of wines. These results would provide not only an approach to improve flavor complexity and characteristics of wines, but also references for application of β-glucosidases from other sources.

Profiling terpene glycosides from ecolly, cabernet gernischet, and muscat hamburg grapes by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Terpene glycosides (TGs) in the berry skins of Ecolly and Cabernet Gernischet (CG) grapes were profiled by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and compared to that of Muscat Hamburg (MH) grapes. The aroma glycosides in grape skins were extracted by methanol, purified using Amberlite XAD-2 resins, eluted in methanol/ethyl acetate, and analyzed by UPLC-Q-TOF-MS. MS/MS fragmentation and the TG database were used for identification, while semiquantification was achieved by the internal standard, octyl-β-D-glucopyranoside. Seven, nine, and thirteen TGs were identified in Ecolly, CG, and MH, respectively, whereas only four TGs were detected in all the varieties. Compared to MH, linalool-3-O-α-L-arabinofuranosyl-β-D-glucopyranoside was unique for Ecolly, and pyran linalool oxide-α-L-arabinofuranosyl-β-D-glucopyranoside was unique for CG. Furthermore, the total concentrations of TGs were 7.32, 3.50, and 81.27 mg/kg in Ecolly, CG, and MH, respectively. Diendiol I-α-D-apiofuranosyl-β-D-glucopyranoside, furanosyl-linalool oxide-7-O-α-L-arabinofuranosyl-β-D-glucopyranoside, and nerol-l-O-α-D-apiofuranosyl-β-D-glucopyranoside were most abundant in Ecolly, CG, and MH, respectively. PRACTICAL APPLICATION: Terpene glycosides (TGs) are important aroma precursors for wines and it is meaningful to reveal the profiles of TGs in grapes. By analyzing the differences of TGs among the Ecolly, Cabernet Gernischet (CG), and Muscat Hamburg grape varieties, it is expected to provide guidance for the study on the aroma characteristics and aroma enhancing brewing of Ecolly and CG grapes. The results may provide technical experience on aroma glycoside identification and their quantification in grapes and wines for future studies.

Transcriptome and Metabolite Conjoint Analysis Reveals that Exogenous Methyl Jasmonate Regulates Monoterpene Synthesis in Grape Berry Skin

Monoterpene is one of the important sources of varietal aroma, which provides a strong floral and fruity aroma in wines. Methyl jasmonate (MeJA) affects plant secondary metabolism. However, the regulatory mechanisms of monoterpene biosynthesis after MeJA application on grapes are not illuminated. In the present study, 10 mM MeJA was used as treatments in Italian Riesling grape at the preveraison stage in different ways, including grape cluster soaking, foliar spraying, and whole vine spraying, designated as T1, T2, and T3, respectively, while a blank group was used as the control (CK). HS-SPME/GC-MS and transcriptome sequencing analysis were performed to investigate the effect of exogenous MeJA on monoterpene synthesis in grape berry skin. The results of GC-MS showed that the application of MeJA induced the accumulation of volatile monoterpenes in grape berry skin, especially linalool, α-terpineol, and oxides. In addition, transcriptome analysis showed that differentially expressed genes were increased from T2 to T3 to T1 compared with CK, and significantly enriched in JA and monoterpene synthesis pathways. T1 application significantly upregulated the mRNA expression levels of LOX2S, AOS, OPR, and JMT involved in the JA biosynthesis pathway, as well as DXS, HMGCR, TPS14, and α-terpineol synthesis genes involved in the monoterpene synthesis pathway compared with T2, T3, and CK. Thus, grape cluster soaking treatment with MeJA could greatly activate volatile monoterpene synthesis. The results will deeply increase our understanding of the monoterpene biosynthesis of grape berry skin in response to MeJA.

Biocatalysis in the winemaking industry: Challenges and opportunities for immobilized enzymes

Enzymes are powerful catalysts already being used in a large number of industrial processes. Impressive advantages in enzyme catalysts improvement have occurred in recent years aiming to improve their performance under harsh operation conditions far away from those of their cellular habitat. Production levels of the winemaking industry have experienced a remarkable increase, and technological innovations have been introduced for increasing the efficiency at different process steps or for improving wine quality, which is a key issue in this industry. Enzymes, such as pectinases and proteases, have been traditionally used, and others, such as glycosidases, have been more recently introduced in the modern wine industry, and many dedicated studies refer to the improvement of enzyme performance under winemaking conditions. Within this framework, a thorough review on the role of enzymes in winemaking is presented, with special emphasis on the use of immobilized enzymes as a significant strategy for catalyst improvement within an industry in which enzymes play important roles that are to be reinforced paralleling innovation.

Study of aromatic profile of different crosses of Monastrell white wines

BACKGROUND

Aromatic compounds are responsible for the final quality of wines. A semi-quantitative analysis was carried out during two consecutive seasons aiming to determine the volatile composition of 12 new white crosses obtained between Monastrell (M) and other varieties, such as Cabernet Sauvignon (C), Syrah (S) and Tempranillo (T) (MC10, MC180, MC9, MC69, MS30, MS33, MS82, MT103, MT19, MV11, MV67 and MV7), using a methodology based on gas chromatography-solid phase microextraction-mass spectrometry.

RESULTS

On the one hand, 30 aromatic compounds were identified belonging to different chemical groups (alcohols, acids, terpenes, norisoprenoids and esters). The results showed how some crosses presented significant differences with respect to their parental. For example, in 2016, Monastrell and Cabernet Sauvignon showed high concentration of alcohols, acids and some terpenes, whereas the corresponding crosses showed a predominance of aromas belonging to esters. In 2017, as a result of edaphoclimatic conditions, the white crosses had higher concentrations of esters and acids. In addition, Monastrell and Cabernet Sauvignon showed similar concentrations of alcohols compared to 2016. On the other hand, sensorial analyses confirmed these results, so that mint and peppermint aromas and a fresh quality were detected in MC69 wine, especially in 2016, and fruity and acid aromas were detected in MC180 wine, which gave it a wide ranging complexity and aromatic potential.

CONCLUSION

The present study reports the first investigation of the volatile composition and sensory characteristics of directed crosses white wines obtained from Monastrell and other varieties, such as Cabernet Sauvignon, Syrah, Tempranillo and Verdejo. The results obtained indicate that the use of some of these white crosses could be a good option for growing them in this Mediterranean area as a result of the contribution of a good quality in the wine aroma. © 2019 Society of Chemical Industry.

Assessment of chemical composition and sensorial properties of ciders fermented with different non-Saccharomyces yeasts in pure and mixed fermentations

This work presents the attempt to enhance the flavor complexity of cider fermented by different non-Saccharomyces species. Pichia kluyveri and Hanseniaspora vineae pure cultures were used as reference ciders. Mixed cultures between all 4 species gave 5 fermentations, where Hanseniaspora uvarum or Torulaspora quercuum were included for apple juice fermentation. Chemical composition and sensorial properties of all ciders were studied. The results indicated that the growth of P. kluyveri and H. vineae were interreacted and also affected by H. uvarum and T. quercuum. H. vineae was more capable of consuming sugar than P. kluyveri. Ciders from the single culture fermentation with P. kluyveri (Pk), as well as from mixed fermentation with P. kluyveri and H. uvarum (Pk-Hu), had high residual sugar, sugar/acid ratio, and glucose-fructose consumption ratio. Large shifts in the consumption and production of organic acids and polyphenols among all ciders were observed. The calculation of the relative odor activity value (rOAV) showed that 17 volatile compounds had an rOAV >1 in at least one sample, and acetate esters and ethyl esters were the groups with the highest number of volatile compounds of importance to the cider aroma. Among these 17 compounds, 3-methylbutyl acetate, 2-methylbutyl acetate, ethyl hexanoate, ethyl octanoate, and β-damascenone exhibited high rOAVs in some ciders and might contribute fruity, floral, and sweet features to the cider aroma. Besides, the tropical fruity aroma from 3-methylbutyl acetate was only perceived in Pk and Pk-Hu. The partial least squares regression (PLSR) analysis revealed that acetate esters contributed positively to the roasted and cooked odor of all ciders. This is the first study evaluating simultaneous fermentation of two non-Saccharomyces yeasts to produce cider, which provides new insights into cider production.

Correlating Noble Rot Infection of Garganega Withered Grapes with Key Molecules and Odorants of Botrytized Passito Wine

Experimental passito wines with different percentages of naturally noble-rotten grapes of the Garganega variety were analyzed to evaluate key molecules and odorants related to the typical aroma and sensory profile of botrytized passito wine. Remarkable changes in the concentration of 1-octen-3-ol, 4-terpineol, benzaldehyde, N-(3-methylbutyl)acetamide, and sherry lactone 1 and 2 were observed between sound and noble-rotten wines. Wines were perceived to be different for floral, honey, figs, apricot, and caramel scents. By partial least square regression these descriptors were well correlated to samples. An important positive contribution of sherry lactones, N-(3-methylbutyl)acetamide, vanillin, benzaldehyde, and γ-butyrolactone to honey, apricot, and caramel was observed. It is conceivable that oxidative effects of Botrytis cinerea infection play an important role in the genesis of these chemical and sensory aroma markers. This study provides a predictive tool for winemakers that use natural grape withering to produce wines whose aroma profile is not standardized due to the seasonal variation of noble rot incidence.

Characterization of two Vitis vinifera carotenoid cleavage dioxygenases by heterologous expression in Saccharomyces cerevisiae

Norisoprenoids are produced from carotenoids under oxidative degradation mediated by carotenoid cleavage dioxygenases (CCDs) and contribute to floral and fruity notes in grape berries and wine. The diversity of CCD substrates and products has been demonstrated by in vitro recombinant proteins extracted from Escherichia coli expressing CCD genes and of in vivo proteins in an E. coli system co-expressing genes for carotenoid synthesis and cleavage. In the current study, VvCCD1 and VvCCD4b were isolated from the cDNA library of Vitis vinifera L. cv. Cabernet Sauvignon and then transformed into carotenoid-accumulating recombinant Saccharomyces cerevisiae strains. The expression of the target genes was monitored during the yeast growth period, and the accumulation of carotenoids and norisoprenoids in the recombinant strains was measured. The results indicated that both of the VvCCDs cleaved β-carotene at the 7, 8 (7', 8') position into β-cyclocitral for the first time. Additionally, the two enzymes also degraded β-carotene at the 9, 10 (9', 10') position to generate β-ionone and cleaved lycopene at the 5, 6 (5', 6') position into 6-methyl-5-hepten-2-one. These findings suggested that the VvCCDs may possess more cleavage characteristics under the eukaryotic expression system in S. cerevisiae than the prokaryotic system in E. coli, which could better explain the biochemical functions of VvCCDs in grape berries.

Physicochemical characterization and quality of Dangshan pear wines fermented with different Saccharomyces cerevisiae

Three commercial yeasts strains, namely, Saccharomyces cerevisiae SY, DV10, and Drop Acid Yeast, were used for Dangshan pear wine fermentation. Monitoring main physical and chemical indexes and scoring comprehensive sensory characteristics to find a suitable yeast to produce Dangshan pear wine. The fermentation cycle of SY was short (15 days), and the SY-fermented wine had a suitable sugar-acid ratio, with a residual sugar content of 3.13 ± 0.05 g/L, total acid content of 3.40 ± 0.11 g/L, and ethanol content of 14.1 ± 0.27% (v/v). Additionally, 42 flavor compounds were detected in fermented Dangshan pear wine, and the total amount of flavor compounds was highest in the SY wine (2,584.72 μg/L). Combined with the comprehensive sensory evaluation scores, these results suggest that Saccharomyces cerevisiae SY was the most suitable strain to produce Dangshan pear wine. PRACTICAL APPLICATIONS: In this study, we compared the physical and chemical indicators of pear wine brewed by different Saccharomyces cerevisiae in the process of fermentation and the final quality of pear wine products. It was concluded that the pear wine produced by Saccharomyces cerevisiae SY had good quality. The study found a strain suitable for the fermentation of pear wine and provided a theoretical basis for the industrial production of pear wine. Next, we can try to use Saccharomyces cerevisiae SY for large-scale production of pear wine and try to sell it on the market.