Effects of malting on β-glucanase and phytase activity in barley grain

The effects of malting on beta-glucan and phytate were investigated in one naked and one covered barley by a full factorial experiment with three factors (steeping temperature, moisture content and germination temperature) each with two levels. Analysis of total content of beta-glucan in the malted samples showed small changes after steeping at the high temperature (48degreesC), while steeping at the lower temperature (15degreesC) gave a significantly lower content. This trend was even stronger for,beta-glucan unextractable at 38degreesC. Analysis of the activity of beta-glucanase for the samples steeped at 15degreesC showed a strong increase over the time of germination, while those steeped at 48degreesC had a much slower development. The other two factors influenced the outcome to a small extent, mainly because the steeping temperature was the most important factor overall where any changes in beta-glucan and P-glucanase were observed. When beta-glucan was extracted at 100degreesC, a larger yield was obtained, and this was influenced by the steeping temperature in a much stronger way than for beta-glucan extracted at 38degreesC. Determination of average molecular weight for beta-glucan extracted at 100degreesC gave a lower value for samples steeped at 15 than at 48degreesC. The design did not have any large effects on phytate degradation and phytase activity. However, it indicated that selective control of the enzymes might be possible, since phytase activity was barely affected by the parameters studied, while beta-glucanase was heavily affected. (C) 2002 Society of Chemical Industry.