WVIT 302 Final Exam Study Guide
Questions and Answers
Yeast - Answer-bags of enzymes used in wine production
What qualities must a yeast have? - Answer-1. can handle extreme temperatures;
2. can get things done on time;
3. can tolerate SO2
What can go wrong with these yeasts during production? - Answer-sulfides-- rotten egg smell-- can
develop if the yeast get stressed and don't have enough food
What do yeast need to perform their function? - Answer-1. YAN (Nitrogen);
2. sugar;
3. vitamins, minerals;
4. Potassium
Where do yeast come from? - Answer-occur naturally in the vineyard, they are all around us
What do yeast do once they're done with their primary function? - Answer-they die off, sink to the
bottom of the barrel/tank and become the lees
, Racking - Answer-taking the clean juice off the lees and getting rid of them; if the lees stay in there for
too long, or you don't aerate them, they can develop the sulfide sulfide smell
SULFIDE - Answer-a chemically reduced form of sulfur-- Rotten eggs-- can get rid of it relatively quickly
SULFITE - Answer-a chemically oxidized form of sulfur-- the good kind, this is what we ADD to wine--
used as an antimicrobial agent and an antioxidant
How does Sulfide occur? - Answer-1. elemental residues from vineyard sprays;
2. high turbidity (solids in juice);
3. yeast strains;
4. must nitrogen deficiencies (DAP additions, etc);
5. other nutritional deficiencies;
6. high fermentation temperatures;
7. fermenter size and shape;
8. inadequate aeration during fermentation;
9. heavy or gross lees contact and extended lees contact
How to prevent Sulfides? - Answer-1. nutrients
2. solids level (in whites)
3. elemental sulfur (no late sprays in vineyard)
4. yeast (use low sulfide producing yeasys)
How to remove Sulfides? - Answer-1. aeration- pumpovers
2. add Copper Sulfate
Questions and Answers
Yeast - Answer-bags of enzymes used in wine production
What qualities must a yeast have? - Answer-1. can handle extreme temperatures;
2. can get things done on time;
3. can tolerate SO2
What can go wrong with these yeasts during production? - Answer-sulfides-- rotten egg smell-- can
develop if the yeast get stressed and don't have enough food
What do yeast need to perform their function? - Answer-1. YAN (Nitrogen);
2. sugar;
3. vitamins, minerals;
4. Potassium
Where do yeast come from? - Answer-occur naturally in the vineyard, they are all around us
What do yeast do once they're done with their primary function? - Answer-they die off, sink to the
bottom of the barrel/tank and become the lees
, Racking - Answer-taking the clean juice off the lees and getting rid of them; if the lees stay in there for
too long, or you don't aerate them, they can develop the sulfide sulfide smell
SULFIDE - Answer-a chemically reduced form of sulfur-- Rotten eggs-- can get rid of it relatively quickly
SULFITE - Answer-a chemically oxidized form of sulfur-- the good kind, this is what we ADD to wine--
used as an antimicrobial agent and an antioxidant
How does Sulfide occur? - Answer-1. elemental residues from vineyard sprays;
2. high turbidity (solids in juice);
3. yeast strains;
4. must nitrogen deficiencies (DAP additions, etc);
5. other nutritional deficiencies;
6. high fermentation temperatures;
7. fermenter size and shape;
8. inadequate aeration during fermentation;
9. heavy or gross lees contact and extended lees contact
How to prevent Sulfides? - Answer-1. nutrients
2. solids level (in whites)
3. elemental sulfur (no late sprays in vineyard)
4. yeast (use low sulfide producing yeasys)
How to remove Sulfides? - Answer-1. aeration- pumpovers
2. add Copper Sulfate
