淀粉凝胶的矩阵构建及消化特性对Ca(OH)2的响应机制研究

Ningxia is the main producing areas of high-quality coarse grains in China. Staple food made of coarse grains, represented by buckwheat etc., is becoming a cause for concern of consumers and food processing industry for its healthy function. However, because of the lack of gluten in coarse grain, commercial production of coarse staple food is difficult, and the sensory characteristics of it are not fully accepted by consumers. And that is the bottleneck of the development of coarse staple food in current. In the previous study, our group found that calcium hydroxide can significantly improve the processing performance of buckwheat dough and sensory quality of buckwheat noodles by changing buckwheat starch gel texture, but the internal mechanism of which is unclear. Effects of calcium hydroxide on the formation process of starch gel, gel rheological properties, gel morphology and molecular aggregation and structure in gel of different starch will be systematically studied in this project, and the action of calcium hydroxide on the separation and rearrangement trend of ordered structure of starch granules will be investigated. The similarities and differences in the action of neutral calcium chloride, monobasic sodium hydroxide and calcium hydroxide on matrix construction of starch gel will be comparatively analyzed. Finally, the mechanism of the response of matrix construction of starch gel to calcium hydroxide will be revealed combined with the theory of carbohydrate science, supramolecular structural chemistry, valence bond theory and rheology. Moreover, the digestibility of starch gel containing calcium hydroxide will be evaluated. This work will provide the theoretical basis and scientific guidance for the development of coarse staple food and other starch-based food riched in calcium.

宁夏是我国优质杂粮主产区，以荞麦等为代表的杂粮因富含保健因子，其主食制品开发已得到消费者和食品加工业界的高度关注。但由于面筋蛋白缺乏，导致其制品口感差，难以实现工业化生产，是当前杂粮主食研发的瓶颈。本课题组在前期研究中发现，氢氧化钙通过改善荞麦淀粉的凝胶质地可显著提升荞麦面团的加工性能和面条的感官品质，但对其内在机理尚不清楚。本项目将系统研究氢氧化钙对不同类型淀粉的凝胶形成过程、凝胶流变特性、形态结构、胶体内分子聚集态及链段构象的影响，从分子结构层次及链段水平考察氢氧化钙对淀粉颗粒有序结构分离与重排趋势的作用方式；对比分析中性钙盐氯化钙、一元碱氢氧化钠与氢氧化钙作用的异同，结合碳水化合物科学、超分子结构化学、价键理论、流变学等理论揭示淀粉凝胶的矩阵构建对氢氧化钙的响应机制；并对氢氧化钙存在下淀粉凝胶的消化特性进行评价。此工作将为杂粮主食及其他淀粉基富钙保健食品的研发提供理论依据及科学指导。

宁夏是我国优质杂粮主产区，以荞麦等为代表的杂粮因富含保健因子，其主食制品开发已得到消费者和食品加工业界的高度关注，但由于面筋蛋白缺乏，导致其制品口感差，难以实现工业化生产，是当前杂粮主食研发的瓶颈。本课题组在前期研究中发现，氢氧化钙通过改善荞麦淀粉的凝胶质地可显著提升荞麦面团的加工性能和面条的感官品质，但对其内在机理尚不清楚。针对如上问题申请了此项目。本项目系统研究了Ca(OH)2对不同类型淀粉的凝胶形成过程、凝胶流变学特性、形态结构及胶体内分子链段构象的影响。主要实验结果如下：.1.OH-可显著提高玉米淀粉的凝沉性，Ca2+则有一定的抑制作用； Ca2+和OH-的协同作用使玉米淀粉的回生值减小，；OH-对玉米淀粉凝胶的质构有一定的破坏作用，Ca2+可显著改善凝胶的质构。.2. Ca(OH)2添加量为0.150%时豌豆淀粉的透明度最大、凝沉性最差，黏度最大。综合对比分析可知，Ca(OH)2对豌豆流变学特性的影响是Ca2+、OH-共同作用的结果。.3. Ca(OH)2添加量在0.025%时，马铃薯淀粉的沉降积最大，凝沉性最小，糊化峰值粘度和谷值粘度最小；添加Ca(OH)2对马铃薯凝胶的弹性、胶黏性、咀嚼性无显著性影响。.4. Ca(OH)2不同类型的淀粉的流变学特性具有不同的影响。Ca(OH)2显著增大了豌豆淀粉和玉米淀粉的弹性及粘性模量，而且随着Ca(OH)2浓度增大豌豆淀粉的模量显著增大，但是当Ca(OH)2浓度达到0.075%时，淀粉凝胶的弹性模量和粘性模量显著下降到跟对照没有显著性差异；但Ca(OH)2对马铃薯淀粉的弹性和粘性模量没有显著影响。如上实验结果的机理还有待进一步探索。.4.当氢氧化钙浓度为0.050%-0.075%之间时，RDS含量出现最低，SDS、RS含量出现最高值，其作用原因可能是Ca(OH)＋将在淀粉颗粒表面形成Ca(OH)＋-淀粉复合物，促进淀粉粒表面淀粉链之间的交联，进而影响了淀粉的消化性。.5质量分数不超过0.24%的碱液，不会对淀粉糊化焓产生显著影响。X-射线衍射和扫描电子显微镜分析结果证明：质量分数小于0.24%的碱液不会对淀粉颗粒形态及内部结构产生显著破坏。碱液提取法可用于荞麦淀粉的制备，但应控制碱液质量分数不能超过0.24%。