Fate of carotenoids in yeasts: synthesis and cleavage.

Carotenoids and their cleavage products (norisoprenoids) have excellent functional properties with diverse applications in foods, medicaments, cosmetics, . Carotenoids can be oxidatively cleaved through nonspecific reactions or by carotenoid cleavage oxygenases (CCOs), the product of which could further modify food flavor. This review provides comprehensive information on both carotenoid synthesis and cleavage processes with emphasis on enzyme characterization and biosynthetic pathway optimization.

The implication of phenolic acid matrix effect on the volatility of ethyl acetate in alcohol-free wine model: Investigations with experimental and theoretical methods.

Hydroxycinnamic acids and ethyl acetate were assessed in simulated alcohol-free wine solutions to explore the effect of phenolic acids on the aroma volatility of esters. The results showed that the phenolic acids could inhibit the volatilization of ethyl acetate, and the extent of inhibition was influenced by the concentration and structure of the phenolic compounds. The ultraviolet absorption spectra of the phenolic acids and ethyl acetate confirmed the interaction between the two compounds.

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.

Increased glycosidase activities improved the production of wine varietal odorants in mixed fermentation of P. fermentans and high antagonistic S. cerevisiae.

A selected Pichia fermentans strain was simultaneously and sequentially inoculated in synthetic and real juice with S. cerevisiae strains of different antagonistic activities in a ratio 1:1 to observe the correlation between varietal odorants and glycosidase activities. Fermentations using pure S.

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.

Evolution of volatile compounds treated with selected non-Saccharomyces extracellular extract during Pinot noir winemaking in monsoon climate.

The dynamic pattern of volatiles during Pinot Noir winemaking in monsoon climate with yeast extracellular extract (EE) treatment was analyzed. EE from selected Pichia fermentans and Rhodotorula mucilaginosa strains, and almond β-glucosidase were added after 12-h alcohol fermentation, and the volatiles were determined every 24 h by GC-MS. After 6-month storage, wine aroma was evaluated instrumentally as well as by well-trained panelists.

Chemical profiles and aroma contribution of terpene compounds in Meili (Vitis vinifera L.) grape and wine.

The chemical profiles and aroma contribution of terpene compounds in Meili grapes and wine were analyzed. Bound terpene compounds were extracted using methanol, purified using Amberlite XAD-2 resin, concentrated in methanol/ethyl acetate, and enzymatically hydrolyzed to release aglycones. Free terpene compounds were identified using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS).

Wine aroma response to different participation of selected Hanseniaspora uvarum in mixed fermentation with Saccharomyces cerevisiae.

Wine aroma response to a selected Hanseniaspora uvarum Yun268 strain was investigated using different inoculation strategies with commercial Saccharomyces cerevisiae yeast, namely, simultaneous fermentation (SiF), sequential fermentation (SeF), S. cerevisiae fermentation treated with extracellular extract of H. uvarum (EE), and pure S.

Aroma modulation of Cabernet Gernischt dry red wine by optimal enzyme treatment strategy in winemaking.

Cabernet Gernischt (CG) is a famous Chinese wine grape cultivar, the red wine of which is known for its green trait, especially when produced from grapes cultivated in regions with monsoon climate. To modify CG wine aroma, three enzyme preparations (H. uvarum extracellular enzyme, AR2000, and pectinase) were introduced in different winemaking stages with Saccharomyces cerevisiae.

Increase of medium-chain fatty acid ethyl ester content in mixed H. uvarum/S. cerevisiae fermentation leads to wine fruity aroma enhancement.

Medium-chain fatty acid (MCFA) ethyl esters, as yeast secondary metabolites, significantly contribute to the fruity aroma of foods and beverages. To improve the MCFA ethyl ester content of wine, mixed fermentations with Hanseniaspora uvarum Yun268 and Saccharomyces cerevisiae were performed. Final volatiles were analyzed by gas solid phase microextraction-chromatography-mass spectrometry, and aroma characteristics were quantitated by sensory analysis.

Evaluation of aroma enhancement for "Ecolly" dry white wines by mixed inoculation of selected Rhodotorula mucilaginosa and Saccharomyces cerevisiae.

To improve the aroma profile of Ecolly dry white wine, the simultaneous and sequential inoculations of selected Rhodotorula mucilaginosa and Saccharomyces cerevisiae were performed in wine making of this work. The two yeasts were mixed in various ratios for making the mixed inoculum. The amount of volatiles and aroma characteristics were determined the following year.

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

Aroma characteristics and their impact volatile components of noble-rot wines elaborated from artificial botrytized Chardonnay grapes, obtained by spraying Botrytis cinerea suspension in Yuquan vineyard, Ningxia, China, were explored in this work. Dry white wine made from normal-harvested grapes and sweet wine produced from delay-harvested grapes were compared. Wine aromas were analysed by trained sensory panelists, and aroma compounds were determined by SPME-GC-MS.

Aroma Glycosides in Grapes and Wine.

The major aroma components in grapes and wine include free volatile compounds and glycosidic nonvolatile compounds. The latter group of compounds is more than 10 times abundant of the former, and constitutes a big aroma reserve in grapes and wine. This review summarizes the research results obtained recently for the identification of aroma glycosides in grapes and wine, including grape glycoside structures, differences in aroma glycosides among grape varieties, hydrolysis mechanisms, and the factors that influence them.

Potential of Glycosidase from Non-Saccharomyces Isolates for Enhancement of Wine Aroma.

The aim of this work was to rapidly screen indigenous yeasts with high levels of β-glucosidase activity and assess the potential of glycosidase extracts for aroma enhancement in winemaking. A semiquantitative colorimetric assay was applied using 96-well plates to screen yeasts from 3 different regions of China. Isolates with high β-glucosidase activity were confirmed by the commonly used pNP assay.

A novel spectral fingerprint analysis to discriminate dry red wines.

A novel spectral fingerprint to discriminate different dry red wines was built using data visualization method. Twelve red wines with different vintages, cultivars and ageing methods from Changli and Shacheng were sampled. Nine fractions of each wine were collected with a reversed-phase C18 column, and then they were lyophilized.

Modulating the formation of Meili wine aroma by prefermentative freezing process.

The influence of a prefermentative freezing process on changes of aromatic characteristics and volatile compounds in Meili wines was studied to optimize freezing parameters and reveal the mathematical relationship between aromatic characteristics and volatile compounds. The wines obtained were characterized by sensory evaluation and stir bar sorptive extraction (SBSE) followed by a thermal desorption-gas chromatography-mass spectrometry analysis. A total of 28 aromatic descriptors from 6 categories of wine aroma terminology were identified by judging with high "modified frequency (MF%)".

Impact of cover crops in vineyard on the aroma compounds of Vitis vinifera L. cv Cabernet Sauvignon wine.

This study compared the influence of different cover crops with clean tillage on wine aroma compounds of 5-year-old Cabernet Sauvignon vines. White clover, alfalfa, and tall fescue were used in the vineyard and compared with clean tillage. Aroma compounds of wine were analysed by solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS).

Relationship between nonvolatile composition and sensory properties of premium Spanish red wines and their correlation to quality perception.

The correlation of nonvolatile composition in wines with quality perception is a critical subject in current enological research, and it is far from being clear. Thus, the present work aims at (1) defining the chemical composition and in-mouth sensory properties of a set of wooded premium Spanish red wines and (2) assessing the implication of their chemical composition in the sensory perception of quality. Therefore, 24 wines were analyzed by sensory descriptive analysis and chemical analysis for nonvolatile composition, and their correlations have been discussed.