Determining the temperature optimum of cereal beta-amylase by introduction of the half-life method

Abstract

To determine the optimum temperature and the thermostability of enzymes in a standardized, accurate way is an elaborate, often time-consuming task. Knowledge of these characteristics of specific enzymes is of enormous importance for many applications, e.g. for optimizing the mashing regimes in breweries. In addition, due to ever-increasing gelatinization temperatures, cereal varieties (especially barley) are being sought and specifically bred whose starch-degrading enzymes exhibit increased optimal temperatures and temperature stabilities. A high-throughput method for the standardized determination of an enzyme’s behavior to temperature was needed. Based on enzyme kinetic considerations, the half-life method was developed in which a small number of measuring points can provide a high density of information. This information encompasses the temperature optimum as well as the thermostability of enzymes that degrade high-molecular substrates, which applies to starch-degrading enzymes during mashing. Several cereal malts were analyzed for their beta-amylase temperature optimum and thermostability. In doing so, several prerequisites were established for using the method to obtain valid and comparable results.