Heat-stress responses regulated via a MYB24-MYC2 complex

Mannoproteins are released at the end of alcoholic fermentation due to yeast autolysis [1]. It has been described a positive effect of these molecules on lactic acid bacteria growth [2]. The main objective of this work was the characterization of different mannoproteins extracted from active dry yeast (ADY) and the assessment of their effect on Oenococcus oeni and malolactic fermentation (MLF).

Red grape pomace can be an important source of polysaccharides, but currently they are little studied and even less with viable and environmental extraction processes (green extraction). These green techniques must be able to break the cell wall so that the compounds contained in the cells, including polysaccharides, are released and can have a great influence on extraction yields, the chemical structure of polysaccharides and applications in wines. Amongst the emerging green techniques most applied to the extraction of bioactive compounds, such as polysaccharides, high-power ultrasound (US) and enzyme-assisted extraction stand out.

Anthocyanin accumulation and extractability were studied in Tannat, Cabernet Sauvignon and Merlot grapes produced in the south of Uruguay in two consecutive seasons. Typical cultivation situations employed in the region for each variety were considered. A follow-up was carried out, considering 60 plants per vineyard, and the harvest was determined according to the technological indices of maturity. Samples of grapes were taken in duplicate in each vineyard periodically along grape maturation. The basic composition, polyphenolic potential and anthocyanin extractability were determined. Also, half of grapes were frozen and later peeled; skin extractions over 24 hs with a solution of 12% ethanol and pH 3.2 were carried out. The anthocyanin contents of the extracts obtained were determined by HPLC-DAD. The levels of anthocyanins reached the highest values before technological maturity. Anthocyanin extractability had a decrease during grape maturation.

Among the many compounds in wine, condensed tannins play an important role in the organoleptic properties of the products; they are partly responsible for astringency, bitterness and also contribute to the color. This research work aims to study the oxidation state of these bio-heteropolymers which is an important lock in the analysis of processed products in order to better control their quality. Indeed, their identification remains at present a challenge because of the large heterogeneity of their degrees of polymerization (DP) based on 4 monomers (epicatechin, catechin, epigallocatechin, epicatechin-3-O-gallate) thus multiplying the number of oxidation products.

The tartaric salts precipitation is one of the main issues regarding wine instability 1. In addition to the well-known and deeply studied phenomena of potassium hydrogentartrate precipitation (KHT), the last decade has been increased the phenomena of calcium tartrate (CaT) precipitation, that is a concern for the wine industry 2.