Oenological Characteristics of Four Non-Saccharomyces Yeast Strains With β-Glycosidase Activity

Advancements and challenges for brewing aroma-enhancement fruit wines: Microbial metabolizing and brewing techniques

Aroma, a principal determinant of consumer preference for fruit wines, has recently garnered much attention. Fruit wines brewing was concomitant with complex biochemical reactions, in which a variety of compounds jointly contribute to the aroma quality. To date, the mechanisms underlying the synthesis of aroma compounds and biological regulation methods in fruit wines have remained ambiguous, hindering the further improvement of fruit wines sensory profiles. This review provides a detailed account of the synthesis and regulatory mechanisms of typical aroma compounds and their contributions to the characteristics of wines. Additionally, Comprehensive involves between microflora and the formation of aroma compounds have been emphasized. The microflora-mediated aroma compounds evolution can be controlled by key fermentation techniques to protect and enhance. Meanwhile, the genes impacting key aroma compounds can be identified, which provide references for the rapid screening of aroma-enhanced strains as well as target formation of aroma by modifying relative genes.

The Life of Saccharomyces and Non-Saccharomyces Yeasts in Drinking Wine

Drinking wine is a processed beverage that offers high nutritional and health benefits. It is produced from grape must, which undergoes fermentation by yeasts (and sometimes lactic acid bacteria) to create a product that is highly appreciated by consumers worldwide. However, if only one type of yeast, specifically Saccharomyces cerevisiae, was used in the fermentation process, the resulting wine would lack aroma and flavor and may be rejected by consumers. To produce wine with a desirable taste and aroma, non-Saccharomyces yeasts are necessary. These yeasts contribute volatile aromatic compounds that significantly impact the wine's final taste. They promote the release of primary aromatic compounds through a sequential hydrolysis mechanism involving several glycosidases unique to these yeasts. This review will discuss the unique characteristics of these yeasts (Schizosaccharomyces pombe, Pichia kluyveri, Torulaspora delbrueckii, Wickerhamomyces anomalus, Metschnikowia pulcherrima, Hanseniaspora vineae, Lachancea thermotolerans, Candida stellata, and others) and their impact on wine fermentations and co-fermentations. Their existence and the metabolites they produce enhance the complexity of wine flavor, resulting in a more enjoyable drinking experience.

Physico-Chemical Characterization of an Exocellular Sugars Tolerant Β-Glucosidase from Grape Metschnikowia pulcherrima Isolates

A broad variety of microorganisms with useful characteristics in the field of biotechnology live on the surface of grapes; one of these microorganisms is Metschnikowia pulcherrima. This yeast secretes a β-glucosidase that can be used in fermentative processes to liberate aromatic compounds. In this work, the synthesis of an exocellular β-glucosidase has been demonstrated and the optimal conditions to maximize the enzyme's effectiveness were determined. There was a maximum enzymatic activity at 28 °C and pH 4.5. Furthermore, the enzyme presents a great glucose and fructose tolerance, and to a lesser extent, ethanol tolerance. In addition, its activity was stimulated by calcium ions and low concentrations of ethanol and methanol. The impact of terpene content in wine was also determined. Because of these characteristics, β-glucosidase is a good candidate for use in enology.

Adaptación y desarrollo del velo de flor en vinos “sobretablas” de la D.O. Jerez-Xèrés-Sherry fortificados con alcoholes no vínicos

The EC 2019/187 shows the rules for the usage of ethyl alcohols to fortify wines. These must be obtained from products derived from agriculture and the use of alcohols of mineral or chemical origin is not authorized. The ethyl alcohols authorized for the fortification in the D.O. Sherry have wine origin. But, there are other alcohols that could be equally productive and at a lower economic cost, such as beet or sugar cane alcohol. The effect that different types of ethyl alcohols may have on the yeasts of flor remains unknown. Our goal was to analyze the effects of other alcohols (beet, sugar cane, etc.) on the development of the veil of flor. In this way, the yeasts that constitute the veil of flor of Fino wines were isolated and identified by microbiological techniques and characterized by molecular tools and by biochemical and microbiological tests such as cellular hydrophobicity, flocculation, acetic acid production, etc. Then, base wines were fortified with different distilled alcohols, such as malt brandy, tequila, among others. Biological aging under the veil of flor was monitored to later determine the volatile fractions. Alcohol from sugar cane could be a promising alternative to fortify Fino wines.

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

The aim of this study was to investigate the effects of purified β-glucosidases from Issatchenkia terricola SLY-4, Pichia kudriavzevii F2-24, and Metschnikowia pulcherrima HX-13 (named as SLY-4E, F2-24E, and HX-13E, respectively) on the flavor complexity and typicality of wines. Cabernet Sauvignon wines were fermented by Saccharomycescerevisiae with the addition of SLY-4E, F2-24E, and HX-13E; the fermentation process and characteristics of wines were analyzed. The addition of SLY-4E, F2-24E, and HX-13E into must improved the contents of terpenes, higher alcohols, and esters, and decreased the contents of C₆ compounds and fatty acids, which enhanced the fruity, floral, and taste aspects, reducing the unpleasant green of wines with no significant difference in their appearance. β-glucosidases from different yeast species produced different aroma compound profiles which presented different flavor and quality. F2-24EW had the best effect on flavor and quality of wine followed by SLY-4EW and HX-13EW. These research results can provide references for the use of β-glucosidases from non-Saccharomyces yeasts to improve the flavor complexity, typicality, and quality of wines.

Effects of Mixed Adding Crude Extracts of β-Glucosidases from Three Different Non-Saccharomyces Yeast Strains on the Quality of Cabernet Sauvignon Wines

The aim of this study was to investigate the effects of crude extracts of β-glucosidase from Issatchenkia terricola SLY-4, Pichia kudriavzevii F2-24 and Metschnikowia pulcherrima HX-13 (termed as SLY-4E, F2-24E and HX-13E) on the flavor complexity and typicality of Cabernet Sauvignon wines. The grape must was fermented using Saccharomyces cerevisiae with single or mixed SLY-4E, F2-24E and HX-13E. The physicochemical characteristics, volatile aroma compounds, total anthocyanins and sensory attributes of the wines were determined. Adding SLY-4E, F2-24E and HX-13E in wines resulted in a decrease in the anthocyanin content, total acids and volatile acids in wines but an increase in the content of terpenes, benzene derivatives, higher alcohols and esters, which may enhance wine sensory qualities and result in loss of wine color. Different adding strategies of β-glucosidase led to a variety of effects on wine aroma. S/H/F-Ew significantly increased the content of benzene derivatives, higher alcohols and long-chain fatty acid esters, which enhanced the fruity and floral flavor of wines. F2-24E significantly increased the content of short- and medium-chain fatty acid esters, acetate esters and carbonyl compounds. The results indicated that the mixed addition of non-Saccharomyces crude extracts and co-fermentation with S. cerevisiae could further improve wine flavor quality.