When it comes to adding yeast to wine, the typical usage rate is 1 gram per gallon of juice. This is a general guideline that many winemakers follow, but it's important to note that being slightly short or long on the amount of yeast is not a problem. In fact, yeast has the ability to reproduce and multiply in order to reach a sufficient number for fermentation to occur.
If you find yourself slightly short on the recommended amount of yeast, don't worry. The yeast will still be able to reproduce and eventually reach a population that can effectively ferment the juice. However, keep in mind that it may take a little longer for fermentation to start if the yeast count is initially low. So, if you're in a hurry to get the fermentation process going, it's best to use the recommended amount of yeast.
On the other hand, if you accidentally add a bit more yeast than the recommended amount, it won't negatively impact the fermentation process. In fact, having a higher yeast count can actually speed up the fermentation process. The excess yeast will simply reproduce and multiply until the population reaches a level at which fermentation can occur. So, if you're not too concerned about the timing and want to ensure a robust fermentation, adding a little extra yeast won't hurt.
It's worth noting that different strains of yeast may have different recommended usage rates. Some strains may require more or less yeast to effectively ferment the juice. So, if you're using a specific strain of wine yeast, it's always a good idea to check the manufacturer's instructions for the recommended usage rate.
In my personal experience as a sommelier and brewer, I have found that sticking to the recommended usage rate of 1 gram per gallon of juice usually yields satisfactory results. However, I have also experimented with slightly higher or lower yeast amounts in different batches of wine. While the differences may not always be significant, it can be interesting to see how variations in yeast quantity can affect the fermentation process and the resulting wine.
To summarize, the typical usage rate for yeast in wine is 1 gram per gallon of juice. However, being slightly short or long on the yeast amount is not a problem, as yeast has the ability to reproduce and reach a population that can effectively ferment the juice. Adding a little extra yeast can speed up fermentation, while slightly less yeast may result in a slightly slower start. Ultimately, the key is to find what works best for your specific wine and experiment if desired.