【作者】 倪娜；

【导师】 张德权；

【作者基本信息】 中国农业科学院 ， 农产品质量与食物安全， 2014， 博士

【摘要】 血浆蛋白是一种营养、廉价的蛋白质资源，可与肌肉共同作用形成良好的凝胶，明显改善肉制品品质。本文以解析血浆蛋白复合型凝胶形成的作用力为目的，以羊背最长肌、羊血浆蛋白为实验材料，研究了羊肉肌原纤维蛋白、羊血浆蛋白热诱导凝胶的凝胶特性以及凝胶形成过程中的作用力变化规律；构建了羊血浆蛋白－羊肉肌原纤维蛋白复合凝胶模拟体系，明确了羊血浆蛋白对羊肉肌原纤维蛋白热诱导凝胶特性的提升作用；从分子间相互作用的角度入手，系统研究了疏水相互作用、静电作用、氢键及二硫键等作用力在复合凝胶形成过程中的作用与贡献；重点研究了肌球蛋白与白蛋白在热诱导过程中的相互作用方式；并在低盐羊肉乳化香肠中进行了应用。主要结论如下：（1）pH对羊肉肌原纤维蛋白热诱导凝胶特性具有显著影响（P＜0.05）。pH7.5时，羊肉肌原纤维蛋白热诱导凝胶的硬度、保水性最高，微观结构致密、有序。形成羊肉肌原纤维蛋白热诱导凝胶的主要作用力为疏水相互作用，较低pH时二硫键也有参与；pH主要影响体系的离子键、氢键等作用力。（2）pH对羊血浆蛋白热诱导凝胶特性具有显著影响（P＜0.05）。pH8.6时，羊血浆蛋白热诱导凝胶的硬度、保水性最高，形成典型的良好线状凝胶结构。pH5.0时羊血浆蛋白变性温度为71.5°C，pH8.6时则为80.9°C，二者与其凝胶点温度一致。凝胶形成过程中，羊血浆蛋白的-螺旋含量总体下降、无规卷曲含量升高。球蛋白、白蛋白聚集体是形成凝胶体的主要蛋白；pH5.0时，其中部分51kDa蛋白质先以二聚体、再以多聚体的形式进行聚集。（3）pH6.2时，羊血浆蛋白－羊肉肌原纤维蛋白复合凝胶中血浆蛋白含量的增加可明显改善复合凝胶的硬度、保水性（P <0.05），其中羊血浆蛋白含量10%时复合凝胶的最终储能模量最高，羊血浆蛋白含量50%时复合凝胶硬度最高（P <0.05）；pH7.5时，羊血浆蛋白含量的增加反而降低了羊肉肌原纤维蛋白的保水性、硬度与储能模量（P <0.05）。pH6.2时，羊血浆蛋白可提高凝胶微观网络结构的有序性，形成了致密的多孔网状结构。（4）疏水相互作用、二硫键是形成羊血浆蛋白－羊肉肌原纤维蛋白复合凝胶的主要作用力。氢键、静电作用的改变对含羊肉肌原纤维蛋白较多的体系的凝胶特性影响较大；而在羊肉肌原纤维蛋白、羊血浆蛋白比例各半的体系中，pH介导的静电作用是造成其体系凝胶特性不同的主要原因。（5）pH6.2时，将50%的白蛋白替代肌球蛋白后可获得较好的凝胶特性；pH7.0时，凝胶性能反而变差。静电作用是造成肌球蛋白－白蛋白复合凝胶特性差异的主要原因，热诱导作用下肌球蛋白与白蛋白之间可形成二硫键交联，该交联反应涉及了肌球蛋白重链的所有部位，但轻链结构因无法提供足量的巯基，而不能与白蛋白发生热聚集反应。（6）添加2%~4%的羊血浆蛋白可明显改善羊肉乳化香肠的保水性、质构特性及感官特性（P<0.05）；当羊血浆蛋白添加量为4%时，总体可接受性评分最高。在低盐羊肉乳化香肠中，羊血浆蛋白并未对产品质量产生不良影响。更多还原

【Abstract】 As a nutritional, low-cost protein resource, plasma proteins could improve the gel properties ofmeat products significantly. To explain the molecular force of plasma proteins composite gelformation, longissimus dorsi muscle and plasma protein of lamb were used for the experimentalmaterial in the present study. The heat-induced gel properties of lamb myofibrillar proteins andplasma proteins were studied. A model system of plasma proteins-myofibrillar proteins composite gelwas constructed, and the effects of plasma proteins promoting to the texture of the heat-induced gelof lamb myofibrillar proteins were verified. The changes of molecular interactions during the processof gel forming was taken as a key point, and that the molecular forces of hydrophobic interactions,electrostatic interactions, hydrogen bonds and disulfide bonds, which promote the forming ofcomposite gel, were explored. The interaction modes of the myosin and albumin were studied. At last,the applications of plasma proteins on the low salt lamb emulsified sausages were studied. The resultswere as follows:(1) pH had a significantly influence on the heat-induced gel properties of lamb myofibrillarproteins (P <0.05). The highest water-holding capacity and hardness of the lamb myofibrillarproteins were both appeared at pH7.5, with a compact and ordered microstructure (P <0.05).Hydrophobic interactions were the main forces during the lamb myofibrillar proteins heat-inducedgel formation, but disulfide bonds had participated in the formation of gel at low pH. Hydrogenbonds and electrostatic interactions were affected by the pH of the systems.(2) pH had a significantly impact on the heat-induced gel properties of lamb plasma proteins (P<0.05). The highest water-holding capacity and hardness of the lamb plasma protein were bothappeared at pH8.6(P <0.05), and the gel was a typically fine-stranded gel with a compact andordered microstructure. The maximum denaturation temperature of the lamb plasma protein was71.5°C at pH5.0, and80.9°C at pH8.6, respectively. Both of the temperatures were the same to thetemperature of storage modulus transition. The fraction of-helix structure declined, and the randomcoil fraction tended to increase during the heat-induced process. The globins and albumin aggregationwere the main proteins to form the gel through disulfide bonds cross-linking. Some of the51kDaglobins aggregated through dimer firstly and then polymer at pH5.0.(3) Increasing the lamb plasma protein concentration, the gel hardness, water holding capacityof the myofibrillar proteins/plasma proteins composite protein gel would be increased significantly atpH6.2(P <0.05). The highest storage modulus was obtained when10%plasma protein added to thelamb myofibrillar proteins (P <0.05), but the highest hardness of the composite gel was appearedwhen50%plasma protein added (P <0.05). On the contrary, the gel hardness, water-holding capacity,storage modulus was decreased at pH7.5(P <0.05). Composite protein gels with high hardness andwater-holding capacity had a compact and ordered microstructure of three-dimensional network at pH6.2.(4) Hydrophobic interactions and disulfide bonds were the main molecular forces for theformation of the composite gel in the system. Changes of hydrogen bonds and electrostaticinteractions had the main effects on the gel properties of the system with high concentrationmyofibrillar of90%. Electrostatic interactions induced by pH changes was the main factors, whichresulted in the difference gel properties of the composite systems with50%myofribillar and50%plasma.(5) Myosin replaced by50%albumin can be improved the gel properties at pH6.2, butdecreased at pH7.0. Electrostatic interactions induced by pH changes was the main factor, whichresulted in the difference gel properties of the composite systems with50%myosin and50%albumin.The crosslinking reaction between myosin and albumin were involved in all the subfragment of MHCexcept the MLC, since MLC was unable to provide enough sulfydryl to form the disulfide bonds.(6) The lamb sausages containing2%~4%lamb plasma proteins had improved the cooking andtextural properties, and sensory characteristics of the emulsified reduced-sodium lamb sausages. Theaddition of4%lamb plasma proteins achieved a highest score of overall acceptability. The lambplasma proteins could be used in the production of emulsified reduced-sodium lamb sausages,without any detrimental effects on the quality of product.更多还原