If you make wine, you may not think it is important to understand the growth cycle of yeast. But if you are serious about making wine, and making the best wine you can possibly think, you need to understand the fine details of the process. One you understand the fine details, even the details that may not be very important will allow you to better react when something goes wrong and you will be able to understand the process as a whole and not just step-by-step. This will make you an expert, not only will you be able to produce great wine but will become an authority in wine making, people will see you for advice. Maybe you would rather not have people seeking you for advice but at times there are benefits.
Yeast growth cycle
The yeast growth cycle has four phases: latency phase, exponential growth phase, Quasi-stationary phase, decline phase.
Yeast latency phase – this phase will last around an hour. During this phase the number of yeast in the population does not increase. This phase is more about the yeast adjusting to a new environment. The to become comfortable and adjust to the new environmental conditions you have put them in before they will begin to increase in numbers.
Exponential growth phase – this begins after the latency phase once the yeast have adjusted and are comfortable with their new environment. This phase can last anywhere from 3 to 6 days. Compared to the initial population numbers in the latency phase, the yeast population will increase anywhere from 1000 times – 10,000 times during the exponential growth phase. The growth of yeast in is highly influenced by temperature, oxygen and concentrations of ammonia and amino acids.
Quasi-stationary phase – during this phase then stop increasing in number. This is because some of the nutrients required for yeast cell division become deficient. The number of cells in this stage can remain stable for 2 to 10 days.
Decline phase -as the name suggests, during this phase the number of yeast cells in the population begin to decrease. The two main reasons the yeast will decrease in number during this phase is, again a lack of nutrients to grow and maintain the population size and also fermentation of grape juice or whatever juice you are using, the fermentation of the juice is producing ethanol which, is toxic yeast.
Winemakers must maintain a population of viable yeast until all the sugars have been fully consumed and fermented. So this would mean the wine maker would want his niece to stay in the Quasi-stationary phase.