Studies On Wheat Flour's Color Stability

Brownness often happened in the course of wheat flour products processing, which influenced the food's flavor and quality seriously. These study had selected 28 varieties and strains as trial materials. The flour whiteness, the flour yellowness, protein content, ash content, the Granular size, extraction rate, Pasta's whiteness and yellowness in 0 h, 12h, 24h, 36h, 48h, 60h, PPO enzyme activity were investigated, the PPO activity in different PH, substrate concentrations and enzyme concentrations were also studied.The result showed that the Granular size and extraction rate had remarkable correlation with wheat flour whiteness, the correlation coefficients were -0.66 and 0.68 respectively. The protein content, ash content and wheat flour PPO enzyme activity have not significant correlation with the wheat flour whiteness. The fresh pasta's whiteness value declined sharply in the course of preserves after 12h, on the contrary, the pasta's yellowness value raised sharply in the same time, while the pasta's whiteness value and yellowness value changed slowly after 36h. The wheat flour PPO activity was correlated significantly with the browning degree, the protein content, ash content and the Granular size and the extraction rate have not significantly correlation to the browning degree yet. The wheat PPO activity was one of the major factors to cause the browning of the pasta. The PH, the substrate concentrations and the enzyme concentrations had remarkable influence on PPO activity. The optimum PH, the substrate concentrations and the enzyme concentrations were 7.6, 0.5mol/l, 2.5ml respectively.