2020, 28(4):105-112.
Abstract:
The paper mainly studies the effect of heat treatment with lactic acid on properties of rice flour and quality of dried rice vermicelli and wet rice vermicelli. Indica rice flour by water milling was selected as raw material and treated with different concentration of lactic acid, damp heat or the combination of lactic acid and damp heat. The gelatinization characteristics, solubility, expansion rate, cooking quality and texture of dry and wet rice noodles under different conditions were studied. The experimental results showed that the heat treatment with lactic acid had a significant effect on the gelatinization properties of rice flour. After heat moisture treatment, lactic acid treatment, and heat treatment with lactic acid, the peak viscosity, trough viscosity, attenuation value, final viscosity, and retrogradation value of rice flour were all reduced. The peak viscosity was highest in the lactic acid treatment (pH=4). Heat treatment with lactic acid had a certain influence on the solubility and swelling capacity of rice flour. Compared with the original sample, both the solubility and swelling degree of treated samples were gradually decreased. In the determination of rice vermicelli cooking quality, after the lactic acid treatment (pH = 4), the broken rate, cooking loss rate of the dried rice vermicelli and wet rice vermicelli all reached the lowest. In the determination of texture quality of rice vermicelli, after heat moisture treatment, lactic acid treatment and heat treatment with lactic acid, the wet rice vermicelli have decreased hardness and chewiness. When the lactic acid treatment (pH=4), the elasticity of the wet rice vermicelli reaches the maximum. In heat moisture treatment, lactic acid treatment and heat treatment with lactic acid, the viscosity of dried rice vermicelli has decreased, in the lactic acid (pH = 4), the maximum elasticity of dried rice vermicelli. The final result: In the case of lactic acid treatment (pH = 4), the effect on improving the properties of rice flour and the quality of rice vermicelli was optimal.
