不同热加工温度对牛肉干脂肪酸及脂肪氧化的影响

Effects of Different Thermal Processing Temperatures on Fatty Acid Composition and Fat Oxidation of Beef Jerky

采用气相色谱-质谱联用技术,测定牛肉干中脂肪酸的组成,研究失水率相同时,不同干燥温度(25、55℃)及熟制温度(85、150℃)对牛肉干中脂肪酸组成和脂肪氧化的影响。结果表明:经热加工后,牛肉干的脂肪酸含量和脂肪氧化程度均有不同程度的变化。经55℃干燥后,不饱和脂肪酸(unsaturated fatty acid,UFA)、多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)和单不饱和脂肪酸(monounsaturated fattyacid,MUFA)含量显著低于25℃干燥(P<0.01),饱和脂肪酸(saturated fatty acid,SFA)含量显著高于25℃干燥(P<0.01),且脂肪氧化程度低于25℃干燥;熟制阶段,25℃干燥后熟制,SFA、UFA、MUFA和PUFA含量变化不显著(P>0.05),而55℃干燥后,经150℃熟制,UFA、MUFA和PUFA含量显著低于85℃熟制(P<0.01),SFA含量显著高于85℃熟制(P<0.01),且脂肪氧化程度高。综上所述,不同干燥温度及熟制温度对牛肉干脂肪酸及脂肪氧化的影响不同,干燥阶段,较高温度(55℃)干燥对牛肉干脂肪氧化的影响小于25℃干燥;熟制阶段,较低温度(85℃)熟制对牛肉干脂肪氧化影响较小。因此,55℃干燥、85℃熟制得到的牛肉干产品,其UFA、MUFA和PUFA含量最高,SFA含量最低,脂肪氧化程度最小,牛肉干营养价值损失最小。

The composition of fatty acids in beef jerky was determined by gas chromatography-mass spectrometry in this study.Under the same water loss rate,the effects of different drying and cooking temperatures on the fatty acid composition and fat oxidation in beef jerky were studied.The results demonstrated that both the fatty acid content and fat oxidation degree of beef jerky changed after thermal processing.During the drying stage,the unsaturated fatty acid(UFA),polyunsaturated fatty acid(PUFA)and monounsaturated fatty acid(MUFA)contents at 55℃were signi?cantly lower than those at 25℃(P<0.01),while the content of saturated fatty acid(SFA)was signi?cantly higher than at 25℃(P<0.01);the degree of fat oxidation was lower than at 25℃.During the cooking stage,the content of SFA,UFA,MUFA and PUFA did not change signi?cantly(P>0.05)after drying at 25℃;after drying at 55℃followed by cooking at 150℃,the content of UFA,MUFA and PUFA was signi?cantly lower than cooking at 85℃(P<0.01)whereas the content of SFA was signi?cantly higher than cooking at 85℃(P<0.01),accompanied by a simultaneous increase in the degree of fat oxidation.In conclusion,the effects of different drying and cooking temperatures on the fatty acid composition and fat oxidation in beef jerky were different.In the drying stage,the effect of drying at 55℃on the fat oxidation was less than at 25℃;in the cooking stage,the effect of cooking at 85℃on the fat oxidation was less than at 150℃.Thus,beef jerky processed with drying at 55℃and cooking at 85℃has the highest content of UFA,MUFA and PUFA,the lowest SFA content,the lowest degree of fat oxidation and the least loss of nutritional value.