Hydrophobicity of stored (15, 35°C), or dry-heated (120°C) rice flour and deteriorated breadmaking properties baked with these treated rice flour/fresh gluten flour

Abstract

Rice flour was stored at 15°C/9 months, at 35°C/14 days, or dry-heated at 120°C/20 min. The breadmaking properties baked with this rice flour/fresh gluten flour deteriorated. In addition, the rice flour was mixed with oil in water vigorously, and oilbinding ability was measured. Every rice flour subjected to storage or dry-heated at 120°C showed higher hydrophobicity, owing to changes in proteins. Then, proteins in the stored rice flour were excluded with NaOH solution, and bread baked with the deproteinized rice flour showed the same breadmaking properties as unstored rice flour/fresh gluten flour. The viscoelasticity of wheat glutenin fraction decreased after the addition of dry-heated rice flour in a mixograph profile. DDD staining increased Lab in color meter, which suggested an increase in SH groups in rice protein. The increase in SH groups caused a reduction in wheat gluten protein resulting in a deterioration of rice bread quality.