Chardonnay Musts Research Articles

Effects of skin contact and settling on the level of the C18:2, C18:3 fatty acids and C6 compounds in burgundy chardonnay musts and wines

In the present study, a skin contact process (maceration) was applied on Chardonnay grapes and the results compared with those from a control sample obtained directly after pressing and without maceration. After the skin contact trial, four different sets of conditions of settling were realized. Routine analyses were carried out on musts and wines at the end of the alcoholic fermentation. It appears that skin contact greatly affects the acidity of musts and wines. From our experiments, two comparisons can be made. The trial of skin contact (16 h at 20 °C) is compared with the control sample within the same conditions of settling (24 h storage at 20 °C). Secondly, from the skin contact trial, four different conditions of settling are compared: 24 h at a low temperature (15 °C); addition of pectinase and 24 h storage at 20 °C; with no settling; 24 h storage at 20 °C. The effects of these different methods of white wine elaboration are demonstrated by the determination of the concentrations of certain C6 compounds and their lipid precursors (C18:2 and C18:3 fatty acids). C6 aldehyde and alcohol compounds (hexan-1-ol, (E) hex-2-en-1-al, (Z) hex-3-en-1-ol and (E) hex-2-en-1-ol) were analyzed by gas chromatography during wine elaboration. Lipid precursors (linoleic (C18:2) and linolenic (C18: 3) acids) were also determined by GC. During skin contact (between 0 and 16 h), the evolution of C6 compounds and fatty acids contents is studied. Analyses show that skin contact begins with an important production of C6 compounds, especially hexan-1-ol and (E) hex-2-en-1-ol. After 2 h of skin contact, a loss of C6 compounds occurs by adsorption on macromolecules and skin components. Without pressing, skin contact induces a loss of C6 compounds. On the other hand, the combined skin contact/pressing increases the release of precursors into the medium and the production of C6 compounds in the must. One of the principal effects of settling is also a loss of hexan-1-ol and is linked to the loss of lipid precursors. In the musts as well as in the wines, settling conditions can change the direct consequences of skin contact.

A simple mathematical empirical model for estimating the rate of heat generation during fermentation in white-wine making

In the present study a mathematical empirical model permitting the calculation of the heat-generation kinetics during fermentation in usual oenological conditions, and with applications in white-wine-making refrigeration-system design, has been obtained. It has been verified in fermentation at different temperatures of Macabeo and Chardonnay musts, with different states of maturity. The musts have been prepared to an industrial level with adequate technology for quality white-wine making. By using a pilot fermentation plant, the musts were fermented at a controlled temperature in 75 1 stainless-steel vessels

Effect of Pomace Contact on Chardonnay Musts and Wines

Wines were prepared from triplicate lots of crushed Chardonnay grapes, which were held under nitrogen for 0, 6, 12, and 24 hours of pomace contact prior to being pressed. For the musts at press and the finished wines, significant increases in pH, total nitrogen, and potassium and decreases in titratable acidity and tartaric acid were observed as pomace contact time was increased. Additionally, a significant increase in ammonia was found in the musts. In the wines, significant increases in total, flavonoid, and nonflavonoid phenols, and in malic acid were measured. The changes in concentration of these components as a function of the extent of pomace contact is illustrated by principal component analyses of the must and wine compositional data. By duo-trio tests, significant differences in wine flavor were found only between the following pairs of wines: 0 <i>vs.</i> 12 hours, 0 <i>vs.</i> 24 hours, and 12 <i>vs.</i> 24 hours of pomace contact. These differences, however, were too small to be characterized. No significant differences were found between pairs of these wines when compared for intensity of fruity aroma, bitterness, or acidity.