Optimising the antioxidant content of red wine

The aim of the study presented in this thesis was to assess the impact of manipulations to red winemaking unit operations on the concentration of cis- and trans-resveratrol and resveratrol glucoside isomers in the resultant wines. An existing sensitive reverse-phase high performance liquid chromatography 'RP-HPLC' method was optimised to detect these compounds in wine, which permitted excellent peak resolution. The influence of four fermentative yeast strains belonging to the Saccharomyces cerevisiae species on the content of these compounds in Vitis Vinifera L. cv. Shiraz grape musts during alcoholic fermentation was assessed.The influence of malo-lactic fermentation 'MLF' in Shiraz wine was assessed using three different commercial strains. The kinetics of extraction during extended maceration was studied over a period of 21 days.The effect of various pomace contacting maceration methods on the level of cis- and trans-resveratrol and resveratrol glucoside isomers was investigated in Vitus Vinifera L. cv. Cabernet Sauvignon grape musts during alcoholic fermentation. The fate of resveratrol and piceid isomers in fortified red wine(port) was studied during the first six months of maturation in either glass or new oak vessels. The primary wine was derived from Shiraz concentrate. The various tests are discussed in detail and results give