Microorganisms: Yeasts, Respiration, and Fermentation Flashcards
What is the primary wine yeast?
Saccharomyces cerevisiae
A member of the fungi family an are unicellular organisms that reproduce by budding.
What kind of Alcohol is in wine?
Ethanol (EtOH)
two carbon alcohol
What is the must?
Must is the crushed grape mixture composed of grape juice, pulp and skins.
What is Brix?
Approximate measure of sugar concentration
What is pomace?
Seeds and skin that remain after pressing
What is a hydrometer?
tool to measure the density of a solution.
What is a refractometer
tool that measure the refractive index of the juice and can be used to measure Brix
What is an Ebulliometer?
measure ethanol content in wine using the boiling point of the sample.
Describe the yeast growth curve
Lag phase - Cell start divding slowly as they begin using sugar
Logarithmic phase - rapid cell growth
Stationary phase - once nutrients ared epleted and cell growth stabalizes
What is respiration?
When cells grow in the presence of oxygen (aerobic)
Yease consumes sugars and produces CO2 and water
What is fermentation?
When cells grow absent the presence of oxygen (anaerobic)
Yease consumes sugar and produces CO2 and alcohol.
What is ideal temperature for fermentation?
Between 10-38 celsius (50 - 100 F)
How can you predict the increase in temperature from fermentation?
For every degree of Brix there is a 1.3 C (2.3F) temp increase.
Eg: a starting Brix of 22 x 1.3C =28.6 ℃ increase
What is the max level of ethanol for yeast survival?
16%
How do you determine the thoeretical yield of ethanol?
for ABW multipy Brix by 0.51
For ABV multiply Brix by .55 to .62
How long does fermentation take?
For red wine, usually a few days becasue of higher fermentation temps
For white wine up to a few weeks beacue of cooler fermentation temps
