【作者】 梁建兰；

【导师】 尚勋武；

【作者基本信息】 甘肃农业大学 ， 作物遗传育种， 2003， 硕士

【摘要】 中国传统的面食品消费对面粉白度和在面制品白度稳定性要求较高。面粉白度和面团的褐变这一现象，严重影响食品的风味和外观商品质量。本研究选用28个品种(系)为试验材料，测定了面粉白度、偏黄度、蛋白质含量、灰分含量、颗粒度、出粉率、面粉(面片)多酚氧化酶活性，以及鲜面片在0小时、12小时、24小时、36小时、48小时、60小时的白度和偏黄度值；研究了PH值、底物浓度、酶液浓度对多酚氧化酶活性的影响。结果表明：面粉的白度与颗粒度有极显著负相关，与出粉率有极显著正相关，相关系数分别为-0.66和0.68。蛋白质含量和灰分含量与面粉白度相关不显著。同时，鲜面片在保藏期的12小时内，白度下降最快，36小时后白度下降缓慢。相反，在保藏期的12小时内，偏黄度上升迅速，36小时候趋于平缓。面粉多酚氧化酶活性在添加底物后15分钟达到高峰并稳定，其活性与面粉的白度相关不显著，但与面片白度下降呈显著正相关，面片的褐变程度随多酚氧化酶活性的增加而加大，与面粉蛋白质含量、灰分含量、颗粒度、出粉率相关不显著，说明面粉多酚氧化酶活性是面片褐变的直接原因。PH值、底物浓度、酶液浓度对多酚氧化酶活性有明显的影响，PH值为7.6时多酚氧化酶活性最大，底物浓度在0.5mol／l以后，多酚氧化酶活性趋于平缓，酶液添加量在2.5ml后，多酚氧化酶活性也趋于平缓。更多还原

【Abstract】 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.更多还原