Requirements for Zinc, Manganese, Calcium, and Magnesium in Wort

Abstract

The effect of wort zinc, manganese, calcium, and magnesium on fermentation performance was investigated in 2-L laboratory fermentations. Trace metals were added at different concentrations to a 16°P wort. CO2 evolution rate, specific gravity, and pH were monitored throughout the fermentation. Fermentation performance was based on the time to end of fermentation. Under the conditions used, zinc was found to be maximally effective at a level of 0.1–0.15 mg/L; lower concentrations can result in slower fermentations. Zinc concentrations do not affect cell growth, but rather affect the specific rate of fermentation. The yeast's history with regard to zinc concentration has an effect on fermentation performance. No effect on fermentation performance was seen by increasing the manganese concentration fivefold, increasing the magnesium or calcium concentration twofold, or varying the Mg++/Ca++ ratio from one to four.