Fermentation grape must

Lonvaud-Funel, A., Joyeux, A., Ledoux, O. (1991b). Specific enumeration of lactic add bacteria in fermenting grape must and wine by colony hybridization with non isotopic DNA probes. J. Appl. Bacterial, 71, 501-508. 

The tirage liquor is a solution formed by the yeasts responsible for the second fermentation, saccharose, grape must, corrected or not, or partially fermented grape must, in the correct proportions to produce the desired pressure of carbon dioxide. Moreover, a small amount of bentonite is usually added in order to facilitate fioc-culation, followed by removal of the lees. The amount of bentonite used is around 3g/hL (Martfnez-Rodrlguez and Polo 2003). 

Romano, P, Caruso, M., Capece, A., Lipani, G., Paraggio, M., Riore, C. (2003a) Metabolic diversity of Saccharomyces cerevisiae strains from spontaneously fermented grape musts. World Journal of Microbiology Biotechnology, 19, 311-315. 

Brettanomyces in must. Researchers isolated Brettanomyces in fermenting grape must from around the world France (10, 27) Germany (18) Italy (23, 48), South Afnca (33) Uzbekistan (37) New Zedand (42) and Spain (40, 49). Brettanomyces populations were rarely found to be the predominate species in the microflora of fermenting musts, although some were detected. Domercq (27) detected two Brettanomyces cultures out of 80 red no cultures were isolated out of 38 white grape musts sampled from French wineries. 

As approximately 18 g/1 of sugar is required to produce 1% vol of ethanol during alcoholic fermentation, grape must has to contain 180, 226 and 288 g/1 of sugar to produce wines with 10,... 

Barre. 1978. Identification of thermobacteria and homofermentative thermophilic pentose-utilizing lactobacilli from high temperature fermenting grape musts. J. AppL Bacteriol 44 125-130. 

Mamede, M.E.O., H.M.A.B. Cardello, and G.M. Pastore. 2005. Evaluation of an aroma similar to that of sparkling wine sensory and gas chromatography analyses of fermented grape musts. Food Chem. 89 63—68. 

Grape musts, partially fermented grape must and new wines that are stiU fermenting. By addition of tartaric add exdusively. 

Regulations specify a considerable Hst of additives and treatments which may be permitted under controlled limits and conditions. It is important to note that no wine receives mote than a few of these treatments, and many have none. For example, most grape musts ferment readily without additions, but some extra nitrogen source for the yeasts is occasionally beneficial. If some is requited, ammonium phosphate is the most commonly used. 

Addition of up to 200 ppm sulfur dioxide to grape musts is customary. Strains of S. cerevisiae and S. bayanus grown in the presence of sulfite, become tolerant of fairly high concentrations of SO2. Cultures propagated in the winery are added in Hquid suspension, usually at 1—2% of the must volume. Many strains are available in pure culture. Factors such as flocculence, lack of foaming, fast fermentation, lack of H2S and SO2 formation, resistance to sulfur dioxide and other inhibitors, and flavor production will affect strain choice. No strain possesses all the desired properties. 

The next step of the biotechnical sequence, yeast fermentation, is of the utmost importance to the chemistry of winemaking as well as to the formation of flavor substances. We have investigated this previously using 14C-tagged compounds (16). Amino acids, for example, enter the yeast fermentation with a quasi biochemical valence with regard to the formation of metabolic side products like alcohols and esters. In that respect, the composition of the fermentation substrate, the grape must, is highly important to the formation of aroma substances by yeasts. 

Glycerine. This is a normal product of the alcoholic fermentation of grape must, 7-14 grams per 100 grams of alcohol being regarded as the limiting amounts thus produced. 

Lopez, C. C., Boselli, E., Piva, A., Ndaghijimana, M., Paprella, A., Suzzi, G., and Mastrocola, D. (2004). Influence of Quinoxyfen residues on Saccharomyces cerevisiae on fermentation of grape musts. Food Technol. Biotech. 42, 89-97. 

In another very recent paper (Son et al., 2009b), the fermentative performances of yeast strains used for grape must fermentation were monitored by NMR and multivariate statistical methods. Characterization of the properties of wine yeasts is important because they affect wine quality. In this paper, the changes of metabolites in must during alcoholic... 

Avenoza, A., Busto, J. H., Canal, N., and Peregrina, J. M. (2006). Time course of the evolution of malic and lactic acids in the alcoholic and malolactic fermentation of grape must by quantitative 1H NMR (qHNMR) spectroscopy. J. Agric. Food Chem. 54, 4715-4720. 

At harvest, the grapes must be transferred with caution into a tank, previously filled up with C02. The gas may come from a carbon dioxide cylinder or from another tank containing fermenting must. After vatting, an exogenous supply of C02 must be provided until berry and yeast fermentation produces this gas in sufficient quantities. Initially, the berries absorb variable amounts of C02, depending on the harvest temperature, for example, 50% of the tank volume at 35 °C. This results in an infusion of outside air, delaying the onset of AM. 

Mauricio, J., Moreno, J. J., Valero, E. M., Medina, M., and Ortega, J. M. (1993). Ester formation and specific activities of in in vitro alcohol acetyltransferase and esterase by Saccharomyces cerevisiae during grape must fermentation.. Agric. Food Chem. 41, 2086-2091. 

Accordingly, Ganucci et al. (2009) evaluated at laboratory scale the fermentative behavior of a Z. rouxii strain in the fermentation of must (44% sugar) obtained from dried Maivasia and Trebbiano grapes, used for Vin Santo production. This strain was able to dominate the indigenous population of S. cerevisiae, allowing to reach in the relevant wine the same ethanol concentration obtained in control trials inoculated with a S. cerevisiae strain. Moreover, lower levels of acetic acid and ethyl acetate were produced in the fermentations carried out by Z. rouxii. 

Ciani, M., Mannazzu, I., Marinangeli, P., Clementi, F., and Martini, A. (2004). Contribution of winery-resident Saccharomyces cerevisiae strains to spontaneous grape must fermentation. Anton. Leeuwen. 85,159-164. 

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