The Effect of Skin Contact, β-Lyase and Fermentation Gradient Temperature on Fermentation Esters and Free Volatile Thiols in Oregon Chardonnay Wine

This study investigated specific winemaking procedures that could increase fermentation esters and volatile thiols in Chardonnay wine during fermentation. These compounds together are known to cause tropical fruit aromas. Two levels of pre-fermentative skin contact (10 °C for 18 h) (yes/no), two levels of β-lyase addition (40 μL/L) (yes/no), and three levels of fermentation gradient temperature, FG0 (constant 13 °C), FG1 (started at 20 °C and after 96 h dropped to 13 °C), and FG2 (started at 20 °C and after ~11.5 °Brix dropped to 13 °C), were evaluated using laboratory-scale ferments in a full factorial design. Esters and the volatile thiols, 3-sulfanylhexan-1-ol (3SH), 3-sulfanylhexyl acetate (3SHA), and 4-methyl-4-sulfanylpentan-2-one (4MSP), were quantified using gas and liquid chromatography methods, respectively. The combination of skin contact and FG1 or FG2 resulted in the greatest levels of esters and thiols in Chardonnay wine. The fermentation gradient was shown to be efficient in reducing volatile compounds normally lost due to evaporation during fermentation. With these different processing techniques, it will be possible for winemakers to achieve different wine qualities depending on their chosen wine style.