Although Yeast Energizers are types of nutrient blends, they also contain components such as vitamin B, diammonium phosphate, tricalcium phosphate, magnesium sulphate, and yeast hulls. Yeast energizers are particularly useful to restart a Stuck Fermentation, as it allows yeast populations to increase in a batch of beer or wine which likely has been depleted of these components due to an earlier yeast population growth. The additional components included in Yeast Energizers are most effective when added 24 hours or more after pitching yeast.
Yeast Nutrient provides nitrogen and ammonium phosphate to the Beer Yeast or Wine Yeast. The nitrogen is used for amino acid generation, while phosphate contributes towards various energetic requirements for the yeast. You'll find urea is sometimes included as a source of nitrogen but not phosphorous. Yeast Nutrients are usually added the yeast prior to pitching.
When to use a yeast energizer or yeast nutrient:
- Unless you are using a lot of sugar (Note: many prepared inexpensive Malt Extract kits and Grape Concentrates do use lots of sugar) you will have no need of either a yeast nutrient or a yeast energizer under typical circumstances in normal alcohol Beer Recipe and Wine Kit production.
- Using Montrachet yeast in White Wine Kits will require some form of extra nitrogen to avoid hydrogen sulfide formation, even under normal circumstances. It is unusual in this requirement. In the absence of sufficient oxygen-based amino acids this yeast goes after the sulfur based amino acids and generates hydrogen sulfide as a side product. To prevent this an additional source of nitrogen is suggested.