液氮冻结温度对冻藏黄鳝脂质氧化和气味变化的影响

Effects of liquid nitrogen freezing temperature on the lipid oxidation and odor changes of Monopterus albus during frozen storage

目的探讨液氮冻结温度对冻藏黄鳝脂质氧化和气味变化的影响。方法测定液氮冻结(-50、-80、-110℃)和-20℃冰柜冻结(对照)的冻藏黄鳝的脂质和游离脂肪酸(free fatty acids,FFAs)含量、过氧化值(peroxide value,POV)、硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARs)、脂肪酸组成、挥发性气味物质,并进行感官评价。结果随着冻藏时间的延长,整体上4种温度条件下黄鳝的脂质、单不饱和脂肪酸(monounsaturated fatty acids,MUFAs)和多不饱和脂肪酸(polyunsaturated fatty acids,PUFAs)含量显著下降(P<0.05),FFAs、POV、TBARs值及饱和脂肪酸(saturated fatty acids,SFAs)含量显著上升(P<0.05)。液氮冻结黄鳝的脂质、MUFAs、PUFAs含量和感官评分高于对照,-80℃和-110℃液氮冻结黄鳝的FFAs、SFAs含量显著低于-50℃液氮冻结和对照(P<0.05);-80℃和-110℃液氮冻结黄鳝的脂质氧化差异基本上不显著(P>0.05)。气相色谱-离子迁移谱法检测出25种挥发性气味物质。此外,液氮冻结温度越低,冻藏黄鳝的正己醛和正丙醛相对含量越低。结论降低液氮冻结温度能够显著抑制冻藏黄鳝的脂质氧化和气味变化,有效保护黄鳝的品质。

Objective To investigate the effects of liquid nitrogen freezing temperature on lipid oxidation and odor changes of frozen Monopterus albus.Methods The lipid and free fatty acids(FFAs)content,peroxide value(POV),thiobarbituric acid reactive substances(TBARs)value,fatty acid composition,and volatile odor substances of Monopterus albus frozen at different liquid nitrogen temperatures(-50,-80,and-110℃)and at-20℃with freezer(control)were measured.In addition,organoleptic evaluation was also carried out.Results With the extension of frozen storage time,the lipid,monounsaturated fatty acids(MUFAs),and polyunsaturated fatty acids(PUFAs)content of Monopterus albus under the 4 kinds of temperature conditions significantly decreased overall(P0.05),while POV,TBARs value,and FFAs and saturated fatty acids(SFAs)content significantly increased overall(P0.05).The lipid,MUFAs,and PUFAs content and organoleptic scores of Monopterus albus with liquid nitrogen were higher than the control.The FFAs and SFAs content of Monopterus albus with the-80℃and-110℃liquid nitrogen were significantly lower than-50℃liquid nitrogen and the control(P0.05).However,there was basically no significant difference in lipid oxidation of Monopterus albus between the-80℃and-110℃liquid nitrogen(P0.05).Twenty-five kinds of volatile odor substances were detected using gas chromatography-ion mobility spectrometry.Furthermore,the lower the liquid nitrogen frozen temperature,the lower the content of hexanal and propionaldehyde in frozen Monopterus albus.Conclusion Lowering the freezing temperature with liquid nitrogen can significantly inhibit lipid oxidation and odor changes of frozen Monopterus albus,leading to desirable quality attributes of the Monopterus albus.