Effects of magnesium, calcium and wort oxygenation on the fermentative performance of ale and lager strains fermenting normal and high gravity worts

The effects of increased magnesium and calcium concentrations in oxygenated and non-oxygenated conventional and high gravity worts under static conditions were investigated. The addition of 500 Mg²⁺ to the oxygenated 1048 OG and 1080 OG worts resulted in the most favourable changes to key fermentation parameters leading to increased ethanol production, enhanced vitality, increased cell numbers and an initial increased rate of fermentation, by an ale and lager yeast strain. Elevated Mg²⁺ levels in the non-oxygenated worts led to increased ethanol production, enhanced vitality and increased cell numbers but to a lesser degree when compared with the oxygenated worts. The addition of 800 ppm Ca²⁺ resulted in decreased fermentation rates, reduced ethanol production, decreased vitality and lowered cell numbers by both the ale and lager strain, in both the conventional and high gravity worts. The detrimental effect of added Ca²⁺ was exacerbated in the non-oxygenated worts.