December 2018 – Science & Wine

Immobilization of yeasts in oak chips or cellulose powder for use in bottle-fermented sparkling wine

December 30, 2018November 10, 2019 Paula Silva

Sparkling wine production comprises two successive fermentations performed by Sacharomyces cerevisiae strains. This post is about a project aimed to develop yeast immobilisation processes on two wine-compatible supports, study the effects of yeast type (IOC 18–2007 and 55A) and the immobilisation support type (oak chips and cellulose powder) on the fermentation kinetics, the deposition rate of lees and the volatile composition of the finished sparkling wine; compare the fermentation parameters of the wines inoculated with immobilised or non-immobilised cells.
According with the last post of the year the use of immobilization supports reports the advantages of rapid yeast elimination and not adding bentonite and does not have a negative impact on the wine sensory profile.

Polyphenols in grapevine leaves: unravelling vein and blade specific traits.

December 23, 2018November 10, 2019 Paula Silva

Grapevine cultivation is of great economic importance worldwide, however, little is known about leaf chemical composition. This post summarizes a study in which the phenolic composition of several Vitis vinifera L. cultivar healthy leaves (separating blades and veins) during the season was quantified. Differences between leaf sectors and among genotypes between were found., Anthocyanins, dihydromyricetin-rhamnoside, hexosides of dihydroquercetin, and dihydrokaempferol exclusively accumulated in veins of healthy grapevine leaves. Astilbin was the only flavanonol detected in blades and the prevalent flavanonol in veins. The results of this study are very important to find out leaf polyphenol potential as a part of grapevine protection mechanisms and to dissect genotype-related susceptibility to pathogens. Furthermore, this data is very important to evaluate the importance of grapevine and vineyard by-products as a source of bioactive phenolic compounds.

Effects of grape pomace on insulin sensitivity: towards a whole use of natural materials in wine production

December 16, 2018November 10, 2019 Paula Silva

Optimization of food processing based on waste decrease has become a mandatory standard within the most developed countries. Winemaking is a seasonal activity, and in grape harvesting period a great accumulation of residues is generated. Usually, winemaking byproducts have been sent to distilleries for obtaining ethanol or to be used as fertilizers or biomass. Nevertheless, these activities are usually carried out by external companies representing economic costs for the wine industry. So, finding alternative solutions for the exploitation and valorization of those byproducts, which would involve economic, social, and environmental advantages, will be of the great interest. Several studies about the chemical composition of winemaking byproducts were done, which confirmed that those represent low-cost sources of many phenolic compounds, which have potential industrial applications (pharmaceutical, cosmetic, nutritional, or agricultural) due to their strong antioxidant, anti-inflammatory, or antimicrobial effects. This post describes a study aimed at evaluating the effect of grape pomace, rich in both extractable and non-extractable polyphenols, on markers of Metabolic Syndrome.

Application of portable micro near infrared spectroscopy to the screening of extractable polyphenols in grape skins: A complex challenge.

December 9, 2018November 10, 2019 Paula Silva

Phenolic compounds are secondary metabolites that not only have well-known health benefits but also add several sensory characteristics to wine. Red grapes (Vitis vinifera L.) contain about four grams of phenolic material per kilo. Most of them are found in berry solid parts and are transferred to the wine during the fermentation stage. Consequently, two important topics in oenology research have typically been the study of phenolic compounds present in grape solid parts and how well these compounds are transferred to wine. Among other techniques, near infrared (NIR) spectroscopy has been applied to study these topics.

Chronobiology in the vineyard

December 2, 2018November 10, 2019 Paula Silva

Chronobiology refers to the periodic rhythms of organisms in response to solar or lunar cycles. Chronobiology is a phenomenon that occurs in many behavioural, physiological and metabolic processes of living organisms. Cycling rhythms in biological organisms can occur with change in seasons (such as flower development or hibernation), to lunar-monthly (marine animal breeding), to changes that cycle approximately every 24 hours (the sleep-wake cycle in many animals), to cycles that last less than 24 hours (REM periods during sleep).