Effects of oxidation on water holding capacity and T2 relaxation of heat-induced gel of myofibrillar proteins isolated from chicken breast muscle | 氧化对鸡胸肉肌原纤维蛋白热诱导凝胶保水性及水分子T2弛豫特性的影响

Chinese. 采用不同氧化程度的羟基自由基氧化体系(含0、0.05、0.1、0.5、1和5 mmol・L-1 H2O2,10 μmol・L-1 FeCl3,0.1 mmol・L-1抗坏血酸)对鸡胸肉肌原纤维蛋白进行氧化(4℃ 24 h),测定蛋白质热诱导凝胶的保水性(WHC),观察凝胶微观结构的变化,并利用低场核磁共振(NMR)研究氧化对肌原纤维蛋白热诱导凝胶中水分子的T2弛豫特性的影响。结果表明:在小于0.5 mmol・L-1 H2O2浓度范围内,凝胶形成致密均匀的网络结构,其保水性随H2O2浓度升高(即氧化程度增大)而逐渐增大;当H2O2浓度增至5 mmol・L-1时,凝胶网络孔径变大,并出现断裂,凝胶保水性显著降低(P0.05);NMR结果拟合后得到的水有4个组分。随着H2O2浓度升高,T23弛豫时间由364.26 ms下降至316.82 ms,弛豫峰面积百分数由84.79%降低至78.38%。表明,适度氧化可以提高肌原纤维蛋白凝胶保水性;保水性改善与凝胶网络结构及水分子的弛豫特性有关。

English. The effects of oxidation on water holding capacity(WHC)and microstructural properties of heat-induced gel of myofibrillar proteins(MPs)were investigated.MPs were isolated from chicken breast muscle,and treated with hydroxyl radical-generation systems(0,0.05,0.1,0.5,1 and 5 mmol・L-1 H2O2,10 μmol・L-1 FeCl3,0.1 mmol・L-1 ascorbic acid,incubation for 24 h).The water relaxation of the gel was characterized using low-field nuclear magnetic resonance(NMR)T2 relaxometry.Scanning electron microscopy and centrifugation showed that the gel had an orderly microstructure and WHC was improved when H2O2 concentration increased from 0 to 0.5 mmol・L-1,but the network was broken with a decreased WHC profile when H2O2 concentration increased from 0.5 to 5 mmol・L-1.The NMR data was fitted to four components.T23 relaxation time decreased from 364.26 ms to 316.82 ms and its peak area fraction decreased from 84.79% to 78.38% as H2O2 concentrations increased.These results indicated that mild oxidation could enhance WHC of MPs gel,in terms of improved gel microstructure and the relaxation properties of water molecules.