乳酸钠结合促渗处理对大黄鱼片冷藏期间品质变化的影响

Effects of sodium lactate combined with osmotic technology on quality changes of large yellow croaker ( Pseudosciaena crocea ) fillets during refrigerated storage

为研究乳酸钠结合促渗处理对大黄鱼片冷藏期间品质变化影响,将样品经去头、尾和去内脏处理,用蒸馏水洗净后沥干,随机分成4组,双频超声组(dual-frequency ultrasound, DUS)、乳酸钠处理组(sodium lactate, SL)、乳酸钠-双频超声联合处理组(sodium lactate combined with dual-frequency ultrasound, SLUS)与对照组(control, CK)。14 d内每隔2 d进行微生物指标[菌落总数(total viable count, TVC)、嗜冷菌数(psychrophilic bacteria count, PBC)]、理化指标[pH值、总挥发性盐基氮(total volatile basic nitrogen, TVB-N)值、硫代巴比妥酸(thiobarbituric acid, TBA)值]、质构分析(texture profile analysis, TPA)、水分迁移[持水力(water holding capacity, WHC)、低场核磁共振(low field nuclear magnetic resonance, LF-NMR)、核磁共振成像(magnetic resonance image, MRI)]、蛋白特性[内源荧光强度(intrinsic fluorescence intensity, IFI)、SDS-PAGE]等指标测定,并结合感官评定综合分析不同处理方式对冷藏大黄鱼品质变化的影响。结果得出,DUS处理可适当抑制样品贮藏前期微生物的生长,CK组和DUS组在第0天时的菌落总数对数值分别为4.31±0.02与3.22±0.09,存在显著差异(P<0.05)。综合TVC与TVB-N值分析,得出DUS组样品的冷藏货架期为8 d;SL处理能在有效抑制微生物生长的同时,改善样品的保水能力和感官品质,使大黄鱼的冷藏货架期延至12 d;SLUS处理方式能减缓样品贮藏期间TVC与PBC的增长,明显抑制样品贮藏期间pH值、TVB-N值与TBA值的升高,保持其良好的质构特性和感官品质;SLUS组样品贮藏期间的TVB-N值、TBA值、硬度值、弹性值与咀嚼性值自第2天与对照组间差异显著(P<0.05)。由WHC、LF-NMR与MRI分析得出,SLUS处理能显著保持样品的水分含量,减缓样品中水分流失的速率;结合内源性荧光强度和SDS-PAGE分析可知,SLUS处理能使蛋白质氧化速率有效降低。综合各项指标分析得出,双频超声辅助乳酸钠处理能在显著延长大黄鱼片货架期的同时,较好地保持冷藏大黄鱼的感官品质,使其货架期延至14 d,比对照组样品至少延长了6 d。该研究结果将能为大黄鱼的贮藏保鲜提供一定的理论参考。

To study the effect of sodium lactate combined with osmotic technology on quality changes of large yellow croaker(Pseudosciaena crocea)during refrigerated storage,samples were treated with head,tail,and viscera removed,washed with distilled water,and drained,then they were divided into 4 groups randomly.Samples were treated by 20/28 kHz,175 W dual-frequency ultrasound(DUS),3%sodium lactate(SL),and sodium lactate combined with dual-frequency ultrasound(SLUS)for 10 min,respectively,samples treated with sterile distilled water for 10 min were used as the control group(control,CK).Then they were drained,put into sterile blender bags,and stored at 4℃.Different parameters,such as microbial indexes[total viable counts(TVC)and psychrophilic bacterial counts(PBC)],physicochemical indexes[pH value,total volatile basic nitrogen(TVB-N),and thiobarbituric acid(TBA)],texture profile analysis(TPA),water migration[water holding capacity(WHC),low field nuclear magnetic resonance(LF-NMR),and magnetic resonance image(MRI)],protein characteristics[intrinsic fluorescence intensity(IFI)and SDS-PAGE],and sensory evaluation were measured every 2 days.Results showed that DUS treatment could properly inhibit the growth of microorganisms at the beginning of storage,the TVC of CK and DUS groups at day 0 were 4.31±0.02 and 3.22±0.09,respectively,which were significantly different from each other(P<0.05).The shelf-life of Pseudosciaena crocea with dual-frequency ultrasound treatment during refrigerated storage was 8 days.SL treatment could improve the WHC and sensory scores of samples.The shelf-life of the large yellow croaker was prolonged to 12 days during the whole storage period.Meanwhile,the WHC of the SL group was significantly higher than those of the CK and DUS groups(P<0.05).SLUS treatment could slow down the growth of TVC and PBC effectively,the increase of pH,TVB-N,and TBA value was inhibited,and its good texture characteristics and quality were maintained at the end of storage.The results of WHC,LF-NMR,and MRI analysis showed that SLUS treatment postponed the migration of immobilized water to free water,indicating that SLUS treatment could greatly maintain the water content and slow down the rate of water loss.The TVB-N,TBA,hardness,springiness,and chewiness of the SLUS group were significantly different from those of the CK group since the 2nd day(P<0.05).From the results of IFI and SDS-PAGE analysis,SLUS treatment could effectively reduce the rate of protein oxidation.Based on the analysis of various parameters,it was concluded that SLUS treatment could prolong the shelf-life of Pseudosciaena crocea for another 6 days when compared with the CK group.In conclusion,dual-frequency ultrasound-assisted sodium lactate treatment could significantly extend the shelf-life of Pseudosciaena crocea and effectively maintained the sensory quality.Results could provide a theoretical reference for the preservation of Pseudosciaena crocea during refrigerated storage.