| dc.description.abstract | This research project was designed to evaluate flash détente and thermovinification relationship to color development and aroma composition. Parameters investigated in this study include standard analyses of wine, colorimetric analyses, and volatile composition characterization. The methods of pre-fermentation include a flash vacuum expansion process, termed flash détente, involving high heat and high vacuum and another technique involving heat only, termed thermovinification. The standard analyses include pH, titratable acidity, and alcohol by volume. The process of flash détente involves a combination of heating wine grape berries from 80 to 90 ºC for a brief period of 2 to 6 minutes. After heating, the solid mass is introduced into a low pressure vacuum chamber below 10 kPa, where, hypothetically, the cellular matrix of the grape skins burst from the inside, giving audible popping sounds, allowing for better extraction of anthocyanins, skin tannins, and other grape skin phenolic compounds in addition to modulating flavor and aroma compounds. Thermovinification involves heat over a longer period, generally 1 to 24 hours, minus the vacuum step. Flash détente and thermovinification resulted in an increase in the wine color density, a measure of the color intensity of red plus yellow/brown pigments. Furthermore, yeast assimilable nitrogen, a measure of nitrogen available to yeast and an indirect measure of volatile concentration formed, increased in both flash détente and thermovinification trials. Volatiles were impacted by processing, resulting in a decrease of undesirable aromas. Results demonstrate ability of the flash détente process to improve the coloration of red wines as well as accentuate fruity characteristics. | |
