| Alaska Pollock which is mainly distributed in the North Pacific,is one of the highest yield in the world.In order to provide theoretical basis for the cold chain logistics of Alaska Pollock,the quality changes during frozen storage,logistics transportation and thawing conditions were studied in this paper.The main research contents and results were as follows:Firstly,textural properties,volatile odor,chromatic aberration,TVB-N value,myofibril protein content and TBA value were measured to evaluate the quality changes of the Alaska Pollock which was frozen at different temperatures（-15℃,-18℃,-20℃,-25℃,-30℃）.The results showed that frozen temperature significantly affected the quality of the Alaska Pollock.In terms of sensory indexes about Alaska Pollock,textural properties appeared varying degrees of degradation with the increase of storage time,and the higher of the frozen temperature,the more obvious changes of the Alaska Pollock.The volatile odor appeared discrepancy when the storage time reached 60 days,and the chromatic aberration didn’t change significantly except that luminosity value L* appeared slightly decreased within 10% during the whole storage.In terms of physical and chemical indexes about Alaska Pollock,the TVB-N value continued to grow and the velocity increased with the rise of storage temperature.The lowest growth rate of TVB-N occurred at-30℃ and the highest one occurred at-15℃。The trend of the change of myofibril protein content were the same as TVB-N.However,TBA value couldn’t be correlated with the quality changes of the Alaska Pollock.Secondly,to investigate the effect of temperature variation includes the range,duration and frequency on the quality of Alaska Pollock,the indexes of sensory（textural properties,volatile odor,chromatic aberration）and the physical-chemical indexes(TVB-N value,myofibril protein content,microstructure,Ca2+-ATPase activity)were assayed periodically in simulated situations of logistics.The Results showed that all of the indexes of textural properties declined more than 25% and the TVB-N value increased by 44% compared with the control in the group which experienced the most severe temperature fluctuation.The TVB-N value of the group which experienced the temperature fluctuation in the range below-18℃ also increased more than 40% and its decline rate of enzyme activity reached 44.16%.The color of the fish didn’t change significantly.The myofibril protein content also decreased caused by the temperature fluctuation.All of the increase of the fluctuation range,duration and frequency would aggravate the degradation of the fish.Even if the temperature fluctuations below-18℃ would have a negative impact on the quality of the Alaska Pollock.So,not only the ambient temperature should be controlled,but also the temperature fluctuation should be to minimized in the process of logistics transportation.Thirdly,the thawing time at different temperature（4℃,0℃,-3℃）and the quality changes of the Alaska Pollock after thawing were studied by analyzing volatile odor,chromatic aberration),TVB-N value,bacterial colonies periodically and sensory evaluation.The results showed that the frozen Alaska Pollock could be thawed after 1.50 h,2.34 h and 3.22 h at 4℃,0℃ and-3℃ respectively.And after thawing,the fish could be kept fresh for 24 h、48 h and 96 h by storing at its thawing temperature（4℃,0℃,-3℃）.Thawing at-3℃was recommended to bring more flexibility in production schedules. |
