Study on the impact of lipoxygenase on antioxidation of beer and its characterization

The lipoxygenase activity in malts currently, widely used in domestic breweries were assayed and its impact on beer antioxidative ability was studied.The basic enzymatic properties of malt lipoxygenase were investigated and the activity of lipoxygenase during malting and mashing was tracked in the industrial production scale.The results showed that the malt contains lipoxygenase, and still retains catalytic activity under common mashing process conditions, resulting in the increase of wort and beer TBA.The optimum pH of malt lipoxygenase was 6.5 and it showed high activity between 20⁴0℃, but the thermal stability rapidly declined when the temperature was higher than 50℃.After the germination, lipoxygenase activity increased substantially, and the peak value of enzyme activity was about five times of that in the original barley.Most of lipoxygenase was destroyed after kilning, even lower than raw barley.When the mash temperature was below 60℃ during mashing, the activity of lipoxygenase in the mash could be detected and this process was critical stage where lipoxygenase catalyzes the oxidation of fatty acids.