One of the nutrients naturally lacking in most wines is nitrogen. Having sufficient nitrogen in the fermentation allows wine yeast to reproduce more readily. The higher the rate of reproduction, the higher the wine’s rate of fermentation. Having adequate nitrogen will also increase the yeast’s tolerance to alcohol.
In certain situations Yeast Energizer is more beneficial than Yeast Nutrient. Just like Yeast Nutrient, the Energizer supplies the wine yeast with much needed nitrogen, but from a wider range of nutrients than just phosphate.