【作者】 金牧；

【导师】 熊幼翎；

【作者基本信息】 江南大学 ， 食品科学， 2009， 硕士

【摘要】 大豆分离蛋白(SPI)作为一种植物蛋白,具有较低的成本和较高的营养价值,常作为食品配料广泛应用于肉制品加工中。但在实际的肉制品加工中,尤其是法兰克福香肠的加工中,现有商业SPI除了填充作用外,对肌肉蛋白凝胶的辅助与提高的积极作用并不十分显著,甚至还有反作用。本论文主要探讨SPI经过酶水解和交联改性后功能性质的变化及其对肌原纤维蛋白(MPI)凝胶性质和法兰克福香肠品质的影响,以期探索出适合于法兰克福香肠的大豆蛋白的改造方法以及使用方法。该研究结果对于促进SPI在香肠中的合理应用,改善香肠品质具有重要的实践意义,对于进一步认识SPI与MPI的相互作用有一定的理论价值。论文以提高SPI的凝胶性质和乳化性质为目标,将碱性蛋白酶(Alcalase)水解和谷氨酰胺转移酶(TGase)交联两种手段结合,对SPI进行改造。通过考察SPI及其水解交联产物凝胶强度、乳化性、持水性等功能性质,以及改造产物的电泳、自由羧基变化等结构信息,研究SPI的改性效果。结果表明:大豆蛋白经过碱性蛋白酶水解、TG交联处理后,性质有了显著改变。经过碱性蛋白酶水解的SPI,在DH5以下,随着水解度的增加,其乳化性不断提高,而乳化稳定性有不同程度的降低。将SPI及其水解产物采用TG交联后,SPI的交联产物的乳化性降低、乳化稳定性提高;而水解物的交联产物的乳化性和乳化稳定性没有显著变化。SPI经过碱性蛋白酶水解后成胶性能急剧下降,TG可以显著提高SPI的凝胶强度,但是对大豆蛋白水解产物的成胶性能没有帮助。酶水解可以提高SPI的抗氧化性,TG对大豆蛋白及其水解产物的抗氧化性影响不显著。对大豆蛋白改造产物的电泳和自由羧基含量研究说明了SPI、SPI水解产物以及水解后再交联产物的分子量和分子量分布的变动,印证了上述蛋白性质结果的合理性。接着论文将天然SPI、SPI水解物以及SPI水解再交联后的产物加入到肌肉纤维蛋白中,探讨在大豆蛋白-肌肉纤维蛋白这个模拟体系中,对混合蛋白的流变学性质及热诱导凝胶性质的影响。对于不使用TG进行交联的肌肉蛋白-大豆蛋白混合蛋白体系,大豆水解蛋白以及水解再交联的大豆蛋白对于肉凝胶体系的作用优于天然未变性大豆蛋白;与天然SPI相比,经过水解交联改性的SPI可以显著提高混合蛋白的乳化性与乳化稳定性以及凝胶强度和弹性模量,例如在4%蛋白浓度下,以大豆蛋白:肌纤维蛋白1:1添加量添加了天然SPI的混合蛋白相比,添加SPI水解交联产物的混合蛋白的乳化性和乳化稳定性分别提高了17%与67%。而对于使用TG进行交联的混合蛋白体系,大豆水解蛋白对于TG的交联效果有显著的负面效应,纯肌肉纤维蛋白TG交联后体系的凝胶强度和弹性模量最强,而SPI与肌纤维蛋白的混合体系其次,大豆水解蛋白则阻碍体系的凝胶形成。最后论文将经过改造的大豆蛋白应用与法兰克福香肠体系,探讨改性SPI对法兰克福香肠蒸煮损失、质构性质以及抗氧化能力的影响。结果显示添加SPI水解交联产物的香肠品质得到提升,蒸煮损失减少,储藏稳定性提高;混合体系中直接添加TG后,未变性SPI与MPI的混合蛋白的凝胶强度显著高于SPI水解产物与MPI的混合蛋白的凝胶强度;在添加了大豆蛋白的香肠中再采用TG处理,结果显示添加SPI的香肠凝胶强度显著强于添加SPI水解产物的香肠,但香肠蒸煮损失效果相反。该结果进一步说明在使用TG的肉制品体系中,天然SPI可以促进TG对混合蛋白的交联效果,而SPI水解产物则不利于TG的作用。以上研究表明,SPI水解产物和TG不适合同时添加到法兰克福香肠体系中。该研究结果对香肠的实际生产有一定的指导意义,对于进一步认识SPI与MPI的相互作用以及TG对于两者的作用机制有一定的学术价值。更多还原

【Abstract】 As a nutritious, low-cost and functional food ingredient, soy protein is the most wildly used protein in processed meats. But its role in stability and quality of meat products is often limited by the insufficient interaction between soy protein and muscle protein. The high thermal stability of soy protein prevent it from being denatured under the normal meat processing temperature. This would affect the improvement of meat products.Enzyme hydrolysis is a common method for altering the conformation of soy protein. Enzymatic hydrolysis can alter functional properties and nutritional value of the proteins. Alcalase is a wildly used enzyme in food industry. It can cleave huge protein into short peptides. TGase is an efficiently enzyme in cross-linking peptides into big ones. The combination of alcalase hydrolysis and TGase cross-linking is supposed to create a good food ingredient in improving the texture properties and anti-oxidant activity for frankfurter.Alcalase hydrolysis decreased the molecule weight of SPI, deduced surface hydrophobicity and gelation either but improved the emuisifying properties and anti-oxidant activity. TG incubation improved the molecule weight of SPI hydrolysates, surface hydrolysate, gelation, anti-oxidant activity at the first beginning.Addition of TG incubated SPI hydrolysates promoted the emulsion activity and emulsion stability in the molden system. It also advanced the texture property and water holding capacity of mixed protein especially when the ratio of SPI to MPI is 1:3.On the basis of work before, the effect of TG cross-linked SPI hydrolysates on texture and antioxidant activity of frankfurters were investigated during refrigerated storage over 7days. TBARS value was measured to evaluate the degree of lipid oxidation. both additions of non-hydrolyzed SPI and hydrolyzed SPI in frankfurters resulted in significant reductions (p<0.05) compared with control. Texture profile analysis showed significant improvement in hardness, springiness, values of TG cross-linked SPI hydrolysate added sausages compared with control. The result suggested that 2 hours TG cross-linked SPI hydrolysate especially when DH=4 added sausage was the most profitable product.TG incubated SPI hydrolysates could improve the quality of frankfurters dramatically compared with native SPI added sausage. This research is meaningful to meat processing factories.更多还原