Alcoholic Fermentation

Question 1

Which sugars do yeast prefer? How does this affect vinification?

Answer 1

Yeast prefer Glucose

Fructose tastes noticeably sweeter, so residual sugar from late harvest wines (where fructose levels exceed glucose levels) will be more pronounced.

Question 2

How do Nitrogen levels in the grape affect alcoholic fermentation?

Answer 2

A certain level of nitrogen is necessary to support strongly fermentative yeast action.

Insufficient nitrogen in the grape must can result in slow fermentation.