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Unformatted text preview: Coinoculated Fermentations Using Saccharomyces Yeasts Affect the Volatile Composition and Sensory Properties of Vitis vinifera L. cv. Sauvignon Blanc Wines E LLENA S. K ING ,* ,, J AN H. S WIEGERS , B ROOKE T RAVIS , I. L EIGH F RANCIS , S USAN E. P. B ASTIAN , AND I SAK S. P RETORIUS School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, Adelaide, SA 5064, Australia, and The Australian Wine Research Institute, PO Box 197, Glen Osmond, Adelaide, SA 5064, Australia Alcoholic fermentation using Saccharomyces wine yeast is an effective means of modulating wine aroma. This study investigated the impact of coinoculating commercial yeast strains (Vin7, QA23, Vin13) on the volatile composition and sensory profile of Sauvignon Blanc wines. Small-scale replicated fermentations were conducted using single-strain and coinoculations of Vin7 with QA23 and with Vin13. The results showed that the chemical and sensory profiles of the coinoculated wines were different from both the single-strain wines and equal blends of the single-strain wines. Volatile thiol analysis indicated that the Vin7/QA23 coinoculated wines were highest in 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), although this pattern was not observed for the Vin7/Vin13 yeast combination. The negative white vinegar aroma and high volatile acidity measured in the Vin7 single-strain wines were not present in the coinoculated wines. This study demonstrates that coinoculations can modify the aroma profile of wines, when complementary yeasts are used. KEYWORDS: Wine; yeast; Saccharomyces cerevisiae ; coinoculation; mixed culture; aroma; sensory; thiols INTRODUCTION A vast number of volatile compounds are formed and modulated by yeast during alcoholic fermentation that signifi- cantly impact the flavor and overall quality of wines. In this way, controlling alcoholic fermentation is an effective method for modulating wine aroma. Volatile thiols are a group of aroma compounds whose significance to wine aroma, particularly Sauvignon Blanc wines, has been widely studied ( 13 ). Some of the most important of these are 4-mercapto-4-methylpentan-2-one (4MMP), 3-mer- captohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), which have aromas described as box hedge , passionfruit , grapefruit and blackcurrant . Research has shown that yeasts are responsible for the release and modulation of volatile thiols from grape-derived, nonvolatile cysteinylated precursors during wine fermentation ( 4, 5 ). Esters, higher alcohols and volatile acids are also groups of volatile aroma compounds produced by yeast metabolism during fermentation. Esters, specifically acetate esters and fatty acid ethyl esters, are present in all wines and contribute, in general, fruity characters that significantly influence wine aroma and quality ( 5 ). Ester production in yeast is catalyzed by alcohol acetyltransferase enzymes ( 6 ). Interestingly, these same enzymes)....
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This note was uploaded on 09/29/2010 for the course VEN 91863 taught by Professor Hildergardheymann during the Spring '09 term at UC Davis.
- Spring '09