焦磷酸钠对氧化猪肉肌原纤维蛋白的谷氨酰胺转移酶交联反应及凝胶性能的影响

Effects of Sodium Pyrophosphate on Transglutaminase Catalyzed Cross-Linking and Gel Properties of Oxidized Pork Myofibrillar Protein

以猪肉肌原纤维蛋白为研究对象,考察焦磷酸钠(sodium pyrophosphate,TSPP)对微生物谷氨酰胺转移酶(microbial transglutaminase,MTG)催化天然和氧化肌原纤维蛋白交联的程度及后续蛋白凝胶特性的影响。结果表明,肌原纤维蛋白的氧化程度随着H2O2溶液浓度的升高而增加,但TSPP在一定程度上可抑制羟自由基对蛋白的攻击,且TSPP处理(+TSPP)样品的MTG交联程度明显高于未经TSPP处理(-TSPP)样品。无论是否添加TSPP,随着H2O2溶液浓度的升高,蛋白凝胶的储能模量(G’)和凝胶强度均逐渐降低,加入MTG后均有所回升,且增幅随着H2O2溶液浓度升高逐渐降低。相对于未经TSPP处理样品,TSPP处理条件下未氧化样品的G’和凝胶强度增幅更高,但氧化时增幅降低速度更快。说明虽然TSPP处理有利于MTG交联引起的凝胶性能提高,但当受到氧化胁迫时,TSPP处理反而对其不利。

In this paper,the effects of sodium pyrophosphate(TSPP)on the degree of microbial transglutaminase(MTG)-induce cross-linking and gel properties of natural and oxidized pork myofibrillar protein were studied.Results showed that the oxidation degree of myofibrillar protein rose with the increase of H2O2 concentration.However,TSPP inhibited the attack of hydroxyl radicals on myofibrillar protein to some extent.Moreover,the cross-linking degree of TSPP-treated(+TSPP)samples was obviously higher than that of untreated(TSPP)samples.Irrespective of TSPP treatment,the storage modulus(G’)and gel strength of protein gels were gradually reduced with increasing H2O2 concentration,but they later rebounded after MTG treatment and the increase was negatively correlated with increasing H2O2 concentration.Compared to the untreated counterpart,TSPP-treated unoxidized samples showed a higher increase in G’and gel strength,but the increment decreased faster upon oxidation,suggesting that TSPP treatment helps MTG cross-linking enhance gel properties of myofibrillar protein despite having a detrimental effect upon oxidative stress.