Wine Yeast

The recommended amount of yeast needed for a healthy fermentation is directly governed by two elements; the initial ºBrix (starting sugar content) of the must, and the factors governing the fermentation itself. 

In general, if a must is 24 ºBrix or below, 1 gram of yeast/gallon of must is recommended. This is assuming, of course, that proper fermentation management will be followed to keep the yeast as stress free as possible (ex: nutrients will be used, temperature and pH will be within acceptable ranges for the chosen strain, etc.) 

However, if the sugars will be starting at 25 ºBrix or above, this alone calls for an increase in the recommended dosage rate. In addition, even at “normal” sugar levels of 24 ºBrix and below, a lack of sufficient nutrients, uncontrolled temperature spikes, inhibitory factors from residual late-season vineyard treatments or even spoilage compounds from mould and rot in the fruit, these factors can each contribute to stressing the yeast population during fermentation. As a result, a smaller percentage of healthy wine yeast will actually make it to the end of the fermentation and the wine will be at a greater risk of becoming sluggish or even stopping fermentation altogether before the sugars have been consumed. Therefore, if the winemaker knows that the yeast will be placed in a potentially stressful situation, then the initial dosage rate should be bumped-up to create a ‘safety in numbers’ kind of scenario. In this case 1.25 grams of yeast/gallon is then recommended

Please note that this larger dosage rate does not take the place of proper fermentation management, it only compliments it by raising the numbers a little more in the winemaker’s favor. True, you may have more wine yeast now, but you will still have to feed and care for them to avoid the usual H2s problems.