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不同储藏条件下小麦粉品质变化规律的研究
Study on the Variation of the Quality of Wheat Flour under Different Storage Conditions
【作者】 蒋甜燕；
【导师】 王明洁；
【作者基本信息】 南京财经大学 ， 农产品加工与贮藏工程， 2010， 硕士
【摘要】 在10、15、20、25、30、35℃等6种温度和55%RH、70%RH和85%RH等3种相对湿度组合的条件下进行小麦粉储藏实验。每隔一定时间取样一次,测定小麦粉的多项指标。储藏试验在55%RH条件下进行了180d,70%RH条件下165d,85%RH条件下90d。对储藏期间小麦粉的主要成分、酶、淀粉特性、面团流变学特性和蒸煮品质的变化进行了分析,并进一步探讨了储藏温、湿度条件与小麦粉品质指标之间的关系。结果如下:（1）组分的变化水分随着时间的推移而趋于稳定,达到平衡水分。在同一相对湿度下,储藏温度（X）与平衡水分（Y）呈负相关（Y=a+bX,b<0）;在同一温度下,相对湿度越大,平衡水分越大。随着储藏时间的推移,蛋白质总量不变,湿面筋含量、面筋持水率、沉降值下降。还原糖、脂肪酸值、酸度在55% RH、70% RH下储藏,呈不同程度地上升趋势;在85%RH的10、15℃下和55% RH、70% RH下,储藏的脂肪酸（Y）与时间（X）呈线性正相关（Y=a+bX）,在85%RH,2035℃下,脂肪酸值先上升后下降,脂肪酸与时间呈显著的一元三次方程关系（Y = a+ bX+ cX2+ dX3）。低温可以保持α-淀粉酶的活力。在中低湿下,α-淀粉酶的活力可以保持较长时间;而在高湿条件下,受水分和温度影响,α-淀粉酶的活性增强。（2）RVA粘度特性的变化在55% RH、70% RH条件下,峰值粘度、衰减值、回生值、最终粘度随着储藏时间的推移而上升;85%RH,2035℃条件下的峰值粘度、最终粘度总体呈上升趋势,衰减值、回生值呈下降趋势。（3）面团流变学特性的变化在55% RH、70% RH下,小麦粉吸水率、面团稳定时间呈现先升后降趋势、面团弱化度呈现先下降后上升的趋势,表明小麦粉面团品质在储藏一段时间后开始出现下降。在85%RH,2035℃下,在20d左右就出现面团稳定时间下降,弱化度上升,弱化度峰宽下降,表明高温高湿不适合小麦粉的储藏。55%RH、70%RH条件下,湿面筋含量、面筋持水率、沉降值、面团吸水率、稳定时间、弱化度等指标（Y）与储藏温度（X1）和时间（X2）均呈极显著的二元线性关系（Y =a+bX1+cX2）。55%RH,70%RH和85%RH条件下的还原糖含量、峰值粘度、衰减值、最终粘度和回生值等指标（Y）与储藏温度（X1）和时间（X2）均呈极显著的二元线性关系（Y =a+bX1+cX2）。（4）蒸煮品质的变化随着储藏时间的延长,小麦粉蒸煮品质下降。馒头比容、色泽、气味、食味、粘性、韧性得分均下降。
【Abstract】 The wheat flour was stored under the treatment combination of six levels of temperature （10、15、20、25、30、35℃） and three levels of relative humidity （55%、70%、85%）. Various quality parameters of wheat flour samples were determined at a certain frequency. The wheat flour was stored for 180d, 165d and 90d under 55%RH, 70%RH and 85%RH, respectively .In this paper, the quality of wheat flour was studied during the storage. The changes of the main components of flour（enzyme activity, starch characteristic, dough rheological properties and cooking quality）were analysed. The relationship between the storage temperature and relative humidity with quality was discussed.The results can be concluded as:（1） the change of componentsThe moisture of wheat flour became stable as the storage progressed, reaching equilibrium in the end. At the same relative humidity, there was a negative correlation between storage temperature （X） and equilibrium moisture content （Y） （Y = a + bX, b <0）. At the same temperature, the higher the relative humidity was, the higher the equilibrium moisture content the samples had.The crude protein content kept constant during the storage. Wet gluten content, water-holding rate of gluten and sedimentation value were decreased.Reducing sugar content, fatty acid value and acid value increased with different degree when the wheat flour was stored below 75% RH. There was a positive linear correlation between the storage time （X） and fatty acid value （Y） （Y = a + bX） under 55% RH,70% RH and85%RH,1015℃. For the condition of 85%RH and 2035℃, those value increased first, then decreased. The relationship of the storage time （X） and fatty acid value （Y） followed one element cubic equation （Y = a+ bX+ cX2+ dX3）.The low temperature can keep the amylase activity . When RH was below 75%, amylase activity was stable for a long time, then decreased. At high RH, amylase activity was increased by moisture of wheat flour and environmental temperature.（2） the change of RVA characteristicsUnder 55% RH and 70% RH, the peak viscosity, setback, breakdown viscosity and final viscosity increased during the storage.Under the condition of 85%RH and 2035℃, the peak viscosity and final viscosity increasd ,while breakdown viscosity and setback viscosity decreased.（3） the change of rheology characteristicsUnder 55% RH and 70% RH, water absorption and stability time increased first and decreased afterwards. The degree of dough softening decreased first and increased afterwards, which indicated that the cooking quality of wheat flour deteriorates after stored for a certain of time. Under the condition of 85%RH and 2035℃, after 20 days, the stability time was decreased and the degree of softening was increased. Therefore, high temperature and high relative humidity should not be utilized for flour storage.Under the condition of 55%RH and 70%RH, the relationship of the wet gluten content, water-holding rate of gluten, sedimentation value, water absorption , stability time and the degree of softening （Y） were binary linear correlated with temperature（X1） and time（X2） （Y =a+bX1+cX2）, so were the reducing sugar content, peak viscosity, breakdown viscosity and final viscosity under the condition of 55%RH,70%RH and 85%RH.（4） the change of cooking quality characteristicsWith the increased storage time, the sensory score for the specific votume, color, luster, odor, stickiness and toughness of steamed bread decreased.