Chapters authored
Strategies to Improve the Freshness in Wines from Warm Areas
Trends in wine consumption are continuously changing. The latest in style is fresh wine with moderate alcohol content, high acidity, and primary aromas reminiscent of grapes, whereas certain fermentative volatiles may also influence the freshness of the wine. In addition, the effects of climate change on the composition of the grapes (high sugar content and low acidity) are adverse for the quality of the wine, also considering the microbiological stability. Herein, different strategies aiming at improving wine freshness are presented, and their performance in winemaking is discussed: among them, the addition of organic acids able to inhibit malolactic fermentation such as fumaric acid; the use of acidifying yeasts for alcoholic fermentation, such as Lachancea thermotolerans; and the selection of non-Saccharomyces yeasts with β-glucosidase activity in order to release terpene glycosides present in the must.
Part of the book: Advances in Grape and Wine Biotechnology
pH Control and Aroma Improvement Using the Non-Saccharomyces Lachancea thermotolerans and Hanseniaspora spp. Yeasts to Improve Wine Freshness in Warm Areas
Lachancea thermotolerans is a yeast species that works as a powerful bio tool capable of metabolizing grape sugars into lactic acid via lactate dehydrogenase enzymes. The enological impact is an increase in total acidity and a decrease in pH levels (sometimes >0.5 pH units) with a concomitant slight reduction in alcohol (0.2–0.4% vol.), which helps balance freshness in wines from warm areas. In addition, higher levels of molecular SO2 are favored, which helps to decrease SO2 total content and achieve better antioxidant and antimicrobial performance. The simultaneous use with some apiculate yeast species of the genus Hanseniaspora helps to improve the aromatic profile through the production of acetyl esters and, in some cases, terpenes, which makes the wine aroma more complex, enhancing floral and fruity scents and making more complex and fresh wines. Furthermore, many species of Hanseniaspora increase the structure of wines, thus improving their body and palatability. Ternary fermentations with Lachancea thermotolerans and Hanseniaspora spp. sequentially followed by Saccharomyces cerevisiae are a useful bio tool for producing fresher wines from neutral varieties in warm areas.
Part of the book: Grapes and Wine
Use of UHPH to Sterilize Grape Juices and to Facilitate the Implantation of Saccharomyces and Other Emerging Fermentation Biotechnologies in Wines
Ultra-High Pressure Homogenization (UHPH) is an emerging non-thermal technology that uses continuous pumping at 200–600 MPa (generally 300), and then the fluid is depressurized against a special valve made with highly resistant alleys and coated with diamond powder. The UHPH process is able to sterilize grape juice or whatever food fluid and at the same time is extremely efficient in inactivating oxidative enzymes. The total elimination of wild microorganisms in grape juice allows the perfect implantation of the selected Saccharomyces cerevisiae starter facilitating the expression of particular metabolic profiles or the expression of specific extracellular activities. Furthermore, the use of complex emerging biotechnologies such as the use of co-inoculations with S. cerevisiae and lactic acid bacteria to perform simultaneously alcoholic and malolactic fermentations works much better if the initial juice has a very low load of wild microorganisms. Additionally, the development of spoilage processes by wild microorganisms that can remain in the wine after fermentation is practically impossible when the initial juice is treated by UHPH. Thus, UHPH helps to obtain wines more stable from a microbiological perspective and therefore safer and more hygienic.
Part of the book: New Advances in Saccharomyces