VIN 189 - Wine Microbiology

1. Discuss the significance of yeasts to wine production
   1. Isolate and enumerate viable yeast cells in a wine sample
   2. Identify the main yeasts common to wine including Bettanomyces/Dekkera, Zygosaccharomyces, Hansenula, Kloeckera, Pichia, Candida, and Cerevisiea
   3. Explain sexual and asexual yeast reproduction
2. Evaluate alcoholic fermentation
   1. Contrast commercial yeast strains and native flora for conducting fermentation
   2. Examine factors affecting yeast growth including temperature, pH, percent sugar, alcohol, and sulfur dioxide
   3. Understand the preparation of commercial yeast cultures
3. Explain how lactic acid bacteria (LAB) affect wine
   1. Differentiate homofermentative and heterofermentative metabolism
   2. Summarize the chemical and sensory affects from malolactic fermentation
   3. Examine factors affecting malolactic fermentation including pH, alcohol, sulfur dioxide, and microbial antagonism
   4. Identify LAB spoilage including re-fermentation, acetic acid formation, and off-aromas of geranium, mousiness, and diacetyl (selected wines)
   5. Observe LAB in winemaking 
4. Discuss Acetic Acid Bacteria as it relates to wine production
   1. Identify the sensory affects of acetic acid, ethyl acetate, and acetaldehyde.
   2. Summarize Acetic Acid Bacteria ecology as it relates to the vineyard, fruit processing, fermentation, and post-fermentation operations
   3. Observe Acetic Acid Bacteria in winemaking
5. Examine microorganism control in the winery
   1. Discuss detergents including alkalines, surfactants, and sequestering agents
   2. Review winery sanitizing agents including chlorine, iodine, quaternary ammonia compounds, sulfur dioxide solutions, and steam use
   3. Summarize techniques of sanitation monitoring including swab tests and direct-contact tests
   4. Evaluate ‘dead-spots’ in the winery which commonly house spoilage microorganisms
6. Examine microorganism control in wine
   1. Discuss the use of sulfur dioxide
   2. Identify appropriate use of potassium sorbate
   3. Contrast techniques of sterile filtration