Bridging wheat kernel microstructure and flour rheology occurring during wheat germination

Wheat germination increases α-amylase activity, leading to significant biochemical and structural changes that influence flour rheological properties. Understanding the correlation between internal kernel structure and flour rheology is essential for predicting processing performance and optimizing the use of germinated wheat in food applications.

In this study, five selected Canada Western Red Spring (CWRS) wheat cultivars were germinated for up to 36 h. Germinated wheat kernels were used for microstructural analysis and whole wheat flour was used for rheological tests and enzyme assays. Germination induced structural degradation across all varieties, including crease widening and increased porosity after 24 h, with more pronounced changes at 36 h. α-Amylase activity increased significantly after 24 h, resulting in lower Falling Number and apparent viscosity values. Extended germination (36 h) also weakened gluten aggregation. Correlation analysis revealed strong links between microstructural and rheological properties, with outer layer thickness having the greatest influence. Total porosity was strongly negatively correlated with breakdown (r = -0.64) and peak maximum time (r = -0.64). Outer layer thickness showed even stronger negative correlations with peak maximum time (r = -0.84), peak viscosity (r = -0.82), and breakdown (r = -0.82).

These results showed that extended germination altered wheat kernel structure and functionality, as evidenced by increased porosity, enhanced α-amylase activity, and reduced gluten aggregation capacity and flour viscosity. Among the structural features, outer layer thickness emerged as a key factor influencing flour rheology. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.