Effects of Heat Denaturation and Interaction in Ingredients on Sponge Structure Formation and Properties of Cakes

研究了用木糖醇与麦芽糖醇、木糖醇与乳醇、葡萄糖与麦芽糖醇、葡萄糖与乳醇四对糖组合代替蔗糖后，海绵蛋糕原料的热变性程度及其相互作用。各组合中糖的比例分别为0:100、25:75、50:50、75:25和100:0。对蛋糕的机械和感官质地进行了测试。实验结果如下：低分子量糖（木糖醇和葡萄糖）和高分子量糖（麦芽糖醇和乳醇）的比例不同，蛋糕烘焙过程的温度分布也有不同的规律。增加低分子量糖的比例，降低了蛋糕烘烤期的最高温度。用差示扫描量热法（DSC）测定了真空干燥饼屑中存在不饱和成分。蛋糕屑的焓值与蛋糕烘焙期间的最高温度呈负相关（r = 0.78），说明烘焙过程中的内部温度对蛋糕中不变性成分的含量有影响。脱脂和干燥饼屑的DSC数据表明，未糊化淀粉存在于未饱和组分中。通过SDS-PAGE和HPLC对真空干燥蛋糕样品的提取液进行分析，发现蛋糕屑中均存在未变性蛋白。蛋白质提取率随低分子量糖比例的增加而增加。蛋糕样品中葡萄糖比例的增加使提取蛋白减少，说明还原糖与鸡蛋蛋白相互作用。低分子量糖的比例越高，蛋糕的质地越软，越湿润。但这些蛋糕有相似的硬度测量流变仪。认为蛋糕质地柔软湿润与海绵结构脆性有关，因为蛋糕中不饱和成分较多。

Degree of heat denaturation and interaction in ingredients of the sponge cakes which were replaced for sucrose to four pairs of sugar combination, these were xylitol and maltitol, xylitol and lactitol, glucose and maltitol, and glucose and lactitol, were investigated. The ratio of sugar in each combination were 0 : 100, 25 : 75, 50 : 50, 75 : 25 and 100 : 0 as percentage. The mechanical and sensory texture profile of the cakes were also examined. The results were as follows.1. The temperature profile for cake baking process showed different pattern according to the ratio of low (xylitol and glucose) or high (maltitol and lactitol) molecular weight sugars. Increase in the ratio of low molecular weight sugars caused lower the highest temperature in cakes for baking period.2. Existence of undenaturated components was indicated by Differential scanning calorimetry (DSC) for vacuum dried cake crumb. Enthalpies of these cake crumbs showed negative relation (r = 0.78) to the highest temperature of cakes for baking period, suggesting that the internal temperature during baking affected to the amount of undenaturated components. The DSC data for defatted and dried cake crumb indicated that the ungelatinized starch existed in undenaturated components.3. It was showed that undenaturated protein remained in cake crumb of all samples by SDS-PAGE and HPLC analysis of the extract from vacuum dried cake sample. The amount of extracted protein increased according to increasing the ratio of low molecular weight sugars. Higher glucose ratio in cake sample decreased extracted protein, indicating interaction of reducing sugar and egg proteins.4. Cakes having higher ratio of low molecular weight sugars were evaluated softer and more moist texture. But these cakes had similar firmness measured by rheolometer. It was suggested that soft and moist texture of cakes related to brittle sponge structure because of larger amount of undenaturated component in these cakes.