ZINC SULPHATE—YEAST FOOD
Zinc Sulphate heptahydrate granular powder is a simple source of zinc for where the nutrient is lacking. Zinc is an essential growth factor for many strains of yeast.
Improved yeast growth
- Faster Fermentations
- Reduction of sulphury characteristics
- Concentrated powdered product—economical in use
A healthy yeast requires many nutrients to sustain its growth. Zinc acts as a metal ion co-factor, catalysing several enzymic reactions that would otherwise not take place or at a very slow rate. An example is alcohol dehydrogenase that yeast uses to manufacture alcohol and C02 under fermentation conditions.
Deficiencies can cause the following symptoms:
Long lag phase
- High pH
- Sticking fermentations
Densky et al. (1966) showed that worts contain from 0.05 - 0.10 ppm (mg/litre) Zn and noted growth stimulation if these worts were supplemented with Zn to a level of 0.5 ppm.
Frey et al (1967) found from 0.04 to 0.07 ppm of Zinc in worts and obtained stimulation of both fermentation and growth at 0.5 ppm. The study also showed that Zinc is not toxic to yeast at the 5 ppm level. (Yeast Technology, Reed & Peppler)
It can help reduce sulphury characteristics of beers by reacting with Hydrogen sulphide produced during the fermentation to precipi-tate insoluble Zinc sulphide.
Rates of Use:
It can be added to the copper during the boil or may be mixed with a small volume of wort and added to the fermenter.
Rates can vary depending on the specific yeast strain used and the composition in the grist. Zinc will typically be added within a range of 0.045 to 0.11 grams per hectolitre of Zinc sulphate heptahydrate. (Equivalent to 0.1 to 0.25 mg/litre as Zn 2+)