MALTING, BREWING AND JUICE MANUFACTURE

Enzymes in the Brewing Industry - In beer manufacture, barley grain is malted (germinated under controlled conditions) and kilned. This malt is extracted to give wort. The wort is cooked and treated with hops, fermented with yeast, filtered and stabilised.

The aim of the malting process is to achieve maximum production of enzymes (particularly α-amylase and β-glucanase) and maximum depolymerisation of starch and β-glucan, with minimal respiration losses. Key enzyme activities are α-amylase, β-amylase, β-glucanase and limit-dextrinase. Xylanase may also be of some importance. In mashing, the aim is to produce maximum quantities of fermentable sugars in a liquor which is easy to filter.

The importance of β-glucan in affecting the rate of wort and beer filtration, and the potential for formation of β-glucan hazes in the final product, the beer, are well documented. The importance of arabinoxylan levels and their effect on filtration rates is less clear.

In the juice industry, enzymes are used to increase juice yield from the pulp, and are also used for juice clarification. Increased yields are obtained by depolymerization of the pectic matrix. However, this comes at a price. Released polymer fragments may self-associate to form hazes or precipitates e.g. arabinan hazes.