PSE猪肉蛋白溶解度的研究

The Study of Protein Solubility Changes of PSE Pork

以PSE猪肉和常规猪肉背最长肌为材料,采用微量凯氏定氮法研究pH(4.0,6.5和9.0)和NaCl浓度(0.1,0.15,0.3,0.5,0.7,0.9 mol/L)对总蛋白溶解度的影响;利用SDS-PAGE电泳分析溶液中的蛋白质组成,并用Quantity One软件分析不同溶液环境下的猪肉总蛋白中蛋白质含量的变化。为进一步分析蛋白溶解度对pH和盐浓度的依赖性,采用荧光光谱技术和Zeta电位测量技术揭示盐浓度和pH对蛋白分子构象的影响,结果表明:pH和NaCl浓度引起猪肉总蛋白中部分蛋白分子组成的改变,并对猪肉和PSE肉总蛋白溶解度均有显著影响。pH对猪肉总蛋白溶解度的影响较为明晰,当盐浓度在试验条件范围时,猪肉和PSE肉的溶解度均随pH值的增加而升高;盐浓度对猪肉总蛋白溶解度的影响则较为复杂。荧光光谱法揭示溶解度变化的原因之一——蛋白质构象的改变。针对PSE猪蛋白和常规猪蛋白,Zeta电位测量结果显示:控制蛋白分子构象的分子内相互作用力是有差异的。这些结果不仅能为养殖户调控PSE肉的生成提供理论基础,还可以指导肉制品行业的PSE肉加工工艺。

Effects of various pH values（4.0, 6.5 and 9.0） and ionic concentrations（0.1, 0.15, 0.3, 0.5, 0.7 and0.9 mol/L） of NaCl on the solubility of two pork quality traits of normal and PSE（pale, soft and exudative） were studied by the micro-Kjeldahl method. The results showed that the solubility of pork protein was influenced by pH as well as ionic concentration of salt. Protein solubility arose with pH increase independent of ionic concentration and pork quality traits. In contrast, effect of ionic concentration was complex and depended on pH. In acidic solutions（pH 4.0）, ionic concentration reduced protein solubility no matter what pork quality trait is. Interestingly, with pH elevating, two pork quality traits illustrated different trends of ionic concentration dependency of solubility. This complex picture of pork protein solubility comes from several factors. First of all is the component variation in pork protein, which was corroborated by SDS-PAGE analyses. The second issue is the configuration modification of pork protein molecules, illustrated by the florescent spectrum technique. All induce the change of intermolecular interactions in protein molecules. Therefore, the solubility of pork proteins presented different trends under pH and salt concentrations. The last point is the difference of intra-molecular interactions of pork proteins in these two traits, demonstrated by zeta potential technique. All results presented may guide the pig farmers to control PSE meat generation and shed the light on pork industry to design and optimize PSE meat processes.