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

• Published in: Starch 2018-03, Vol.70 (3-4), p.n/a
• Main Authors: Frauenlob, Johannes, Hetebrij, Edwin, D'Amico, Stefano, Schoenlechner, Regine
• Format: Article
• Language: English
• Subjects: Amylases; Bread; Flour; Inhibition; Mode of action; rapid visco analyser; RVA; Silver; Silver nitrate; Storage; Viscosity; Wheat; α-Amylase
• ISSN: 0038-9056; 1521-379X
• DOI: 10.1002/star.201700123

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 four 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 12–28%. 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 22–43% 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. Wheat flour storage. Technological properties of wheat flour change during storage. These changes are influencing dough rheology and pasting behaviour. In this study, it is demonstrated, that changes in pasting properties are mainly attributed to a substantial decrease in α‐amylase activity during storage. A further promising finding is the implementation of RVA differential‐curves to study enzyme action during flour pasting.