Role of α‐Amylase in the Pasting Behavior of Wheat Flours Upon Storage

Wheat flour pasting properties change during flour storage. Only little is known about the contribution of α-amylase on this effect. This study aimed to monitor the changes in rapid visco analyser (RVA) pasting viscosities of 4 different wheat flours during 360 days of storage. To get an isolated view on the influence of α-amylase, RVA curves were determined either with water or with 2 mM silver nitrate to inhibit α-amylase. After 360 days of storage RVA final viscosity of the flours increased between 31 and 56%. When α-amylase was inhibited it increased only by 12 to 28%. Remarkably, trough viscosity did not change during a storage time of 180 days when α-amylase was inhibited. To estimate the α-amylase activity of flours the ratio between peak viscosities of flour with and without inhibition was calculated. The estimation resulted in a decrease of α-amylase activity by 22 to 43% during 360 days of storage. These findings suggest that the decrease of α-amylase activity is a major influencing factor in the increase of pasting viscosity during flour storage. Additionally, differential curves from analyses with and without α-amylase inhibition are a helpful tool to improve the understanding of the enzymes mode of action.