光氧化与氧气对牛肉保鲜过程中品质以及蛋白理化性质的影响

Effects of Photooxidation and Oxygen on Beef Quality and Physicochemical Properties of Protein during Storage

为探究光照和氧气对牛肉贮藏品质以及肌原纤维蛋白理化性质的影响,以新鲜牛肉为研究对象,测定在4℃条件下不同贮藏期(0、1、2、3、4、5d)牛肉的pH值、色泽、总挥发性盐基氮含量、丙二醛含量、微观结构、蛋白质肽段的组成和蛋白质羰基、巯基、二聚酪氨酸含量等指标。结果表明,随贮藏时间的延长,自然贮藏条件下(有氧、自然光、4℃),牛肉的总挥发性盐基氮、丙二醛含量增加,并且在5d均超过标准限值,牛肉组织微观结构发生变化,出现交联和降解片段,牛肉发生变质,不宜食用,而隔绝氧气和避免光照均能延缓牛肉的变质;肌原纤维蛋白的羰基含量逐渐增加,巯基含量逐渐减少,而氧气更能加速羰基含量的增加,光照对巯基含量的减少作用更明显,并且更能促进肌原纤维蛋白的降解。综上,光和氧共同作用下,鲜牛肉保存不能超过4d,并且光、氧均能促进蛋白氧化而发生交联聚集。

In order to explore the effects of light and oxygen on the storage quality of beef and the physicochemical properties of myofibrillar protein,the pH,color,total volatile basic nitrogen(TVB-N)content,malondialdehyde(MDA)content,microstructure,peptide composition,carbonyl,sulfhydryl and dimeric tyrosine contents of protein in fresh beef were determined during 0–5 days of storage at 4℃.The results showed that under natural storage conditions(aerobic,natural light and 4℃),the TVB-N and MDA contents increased with storage time,exceeding the standard limit on day 5;the microstructure of beef changed with the occurrence of crosslinking and degradation fragments,and its quality deteriorated and was no longerfit for consumption.Anaerobic and dark conditions could delay beef quality deterioration.As storage time increased,the carbonyl content of myofibrillar protein gradually increased,and the sulfhydryl content gradually decreased.Oxygen could more accelerate the increase of carbonyl groups than light,while light was more effective in reducing sulfhydryl groups.In summary,fresh beef should not be stored for four days under light and aerobic conditions.Light and oxygen can promote protein oxidation and cross-linking aggregation.