Study On The Quality Change Of Yellowfin Tuna In Simulated Logistics Process

Yellowfm tuna,named for its anal fins and dorsal fins,is a fish that lives in the upper middle of the ocean and is widely distributed in tropical waters of the Indian Ocean,Pacific Ocean and Atlantic Ocean.Meat of yellowfin tuna is pink,which is rich in protein,DHA and EPA.Yellowfin tuna is famous in international market for its nutritional value,and pollution-free.Currently,Europe,the United States and Japan are the main consumer markets for tuna.Compared to other countries,the development tuna industry in China has been greatly limited.One of the major reasons is the shortage of transport vehicles with ultra-low temperature,therefore the quality of tuna cannot be guaranteed.Tuna is rich in myoglobin,which can be oxidazed in a short time.In order to remain tuna's nutrition,color and taste,it is required to be quick-frozened under-60?,preserved and distributed under-55?(Chinese industry standard SC/T 9020-2006).If these requirements cannot be achieved,its beneficial active ingredients will degrade and convert into harmful ingredients.Most of the yellowfin tuna sold in Chinese markets is ultra-low temperature tuna.The yellowfin tuna was treated in a low temperature environment immediately after being caught and then transported to land.Currently,the existing domestic cold storage and refrigerator can meet the ultra-low temperature requirements.But in the transport process,such ultra-low temperature requirements can be hardly achieved,due to the energy costs and inadequacies of transport vehicles with ultra-low temperature.Usually,ordinary refrigerated trucks are used in transportation of tuna products.The non-compliance conditions will shorten the shelf life of tuna products,and affect its final quality.Therefore,study the quality and shelf life changes of yellowfin tuna in the logistics process,to get the best condition for its transportation,and to ensure its quality in market circulation and logistics process,are of great significance.In this paper,yellowfin tuna was chosen as the research object,its quality was monitored by sensory evaluation,physical,chemical methods,and bacterial counts.The aim was to study the effects of different packaging materials and packaging methods on quality of yellowfin tuna,and to establish its shelf life prediction model.The mainly results were as follows.1.The effects of different packaging materials on the quality of yellowfin tuna in the process of logistics were analyzed.To simulate the logistics process in real-world distribution chain,the yellowfin tuna samples were stored at 4? for 120 h.Then,the texture,water holding capacity,color difference,pH value,TVB-N value,TBA value,methemoglobin(MetMb),K value and histamine levels in the control group,PE packaging group and nano-packaging group were tested.The results showed that the hardness,elasticity,chewiness,water holding capacity,a*and a*/b*of the three test groups were decrease with the prolonging of storage time.Among them,the trend of nano-packaging group was the slowest.TVB-N value,TBA value,MetMb,K value and histamine showed an increase trend,but the trend of nano-packaging group was the slowest,followed by PE packaging group.Therefore,PE packaging materials and nano-packaging materials had a buffer effect on the quality of yellowfin tuna in logistics process,and the effect of nano-packaging materials were better than PE packaging materials.2.The effects of different packaging methods on the quality of yellowfin tuna in the process of logistics were studied.The sensory evaluation,physical evaluation and chemical evaluation of air packaging,vacuum packaging(VP)and modified packaging(50%CO2 + 50%N2)(MAP)yellowfin tuna were stored at 4? for 120 h.Compared with the air packaging(AP)group,both the VP group and the MAP group had positive effects on yellowfin tuna's freshness.According to the data of a*,a*/b*,MetMb and TBA,it could be concluded that VP and MAP have positive effects on maintaining the flesh color and preventing the oxidative rancidity of fat of yellowfin tuna.MAP group had advantages in sensory evaluation,water holding capacity,alleviating the degradation of ATP and inhibiting the formation of histamine.Hardness,elasticity and chewiness could be used as an indicators to evaluate the quality of yellowfin tuna,while adhesiveness,cohesiveness and L*were not suitable for evaluating the quality changes of the yellowfin tuna.The changes of pH value were not significant among three groups,so it was not suitable for accurate assessment of what kind of packaging was more conducive to maintaining the quality of yellowfin tuna.Therefore,MAP could be used to ensure a better quality of yellowfin tuna in the logistics process.3.In order to explore the quality change and shelf life of yellowfin tuna in the process of logistics,the shelf life prediction model was established by studying the quality indexes under different storage temperature.The sensory evaluation,acid value,TBA value,histamine and total number of colonies of yellowfin tuna samples were measured under the conditions of 15?,4? and 0?.The results showed that the scores of acid value,TBA value,histamine and colony increased with the prolongation of storage time,and the higher the temperature,the more obvious the trend was.Besides these,the acid value,TBA value,histamine level and colony count of yellowfin tuna were fitted well with the first order chemical reaction kinetics model(R2>0.90).The total number of colonies also had an acceptable fitness with the first-order chemical reaction kinetics model(R2>0.75).When these data were fitted to Arrhenius kinetic equation,the kinetic model of acid value,TBA value,histamine and colony count and storage time and storage temperature was established.The results showed that the fitting accuracy was high(R3>0.94).Finally,the shelf life predicting model of MAP tuna were established.When the predictive shelf-lives were compared with the observed ones,most of the relative errors were within ± 15%.Therefore,these models are able to predict storage lives of MAP yellowfin tuna samples in real-world distribution chain.