The Effect Of Heating Process On The Quality Of Penaeus Vannamei And Its Shelf Life During Storage

As the model of 'sea shrimp farmed in freshwater',Penaeus vannameiis the major species for farming and the annual production is huge.It is of rich nutrition and tastes delicious,and the color is attractive after cooking.Therefore,they are very popular among the consumers.With the accelerated pace of people's lives,fast food is more and more popular.Boiling is the most commonly used method to prepare shrimp,and proper heat treatment helps to improve the quality of shrimp.However,excessive heat treatment can result in the degradation of edible quality and reduce product value.In this paper the quality of Penaeus vannamei during boiling was investigated,to explore the critical control time under different precast temperature,to provide the theoretical basics for the product's development and the natural preservatives' promoting.On the other hand,the whole shrimp and it's products were easy to turn brown,resulting short shelf life,which influenced seriously the value of shrimp.In this paper,the shelf life of the shrimp when store with different concentration of ferulic acid,caffeic acid and chlorogenic acid was investigated to find out suitable antistaling agent and their concentrations,providing theoretical basis for the use of these natural anti staling agent.Firstly,to find out the quality change and pick out the main indicators for judging the critical control time of shrimps during heated working process,the core temperature,cooking loss,relatively extraction rate of MFP(myofibrillar protein),color,hydroxproline of unpeeled raw Penaeus vannamei were evaluated during boiling in 80?.Furthermore,these indicators were validated in different cooked temperature(60? to 100?).The texture was measured by textural analysis,the water distribution was measured by low filed NMR,the micro-structure was observed by paraffin section technique,and the taste was studied by electronic tongue.Results showed that when boiled at 80?,the core temperature and cooking loss increased with the time,and the relatively extraction rate of MFP dropped below 10%at 2 min which was cooked.L*value also increased to a steady state at 5 min.The relative value of T21 was declined during boiling.T22 accounted for the highest proportion and it declined at the beginning of the cooked,after rising slightly and then continue to fall.The relative value of T23 was increased.Shear force,hardness and chewiness increased firstly and then decreased and the highest values of them appeared at 8 min.and little change after boiled for 60 min.Compared to fresh muscle which muscle fiber was integrated and tight,at 80?,muscle fibers shrank and the densification of perimysium declined after boiled for 3 min.Gaps between muscle fibers expanded at 40 min and began to break up at 60 min.Most of them broke up at 150 min.Hydroxproline content in shrimp was decreased.The richness was the highest content in shrimp,reached to the peak value at 8-10min.Based on the results,the better quality was found when boiled for 2-60min,and the best time was at 8-10 min when boiled at 80?.It is speculated that the aging time ofshrimp could be evaluated by L*value,the tissue broken time could be established by texture and microstructure analysis.higher The temperature was,shorter the time suitable for processing was.Based on the pre-cooking condition:boiling for 2 min at 100?,after which the shrimps were stored at 4? with additions of 0.5%or 1%ferulic acid,caffeic acid or chlorogenic acid,respectively.The TNC,TVB-N,pH,TBARS,shear force and brown stain changes were evaluated.The study found that in the process of storage,the values of TNC,TVB-N,pH and TBARS increased,and shear force value was declined,and browning degree increased.But the ferulic acid,caffeic acid and chlorogenic acid were shown to slow the TNC value,TVB-N value,pH value,TBARS value and browning situation.0.5%caffeic acid and 0.5%chlorogenic acid can prolong the shelf life for 3 days,0.5%ferulic acid,1%ferulic acid,1%caffeic acid and 1%chlorogenic acid can prolong the shelf life for 5 days.Chlorogenic acid showed strong inhibitory ability to microbial growth.The ferulic acid was the most effective to the browning inhibition.As concentration increased,the inhibitory effects became stronger.