Study On Marination And Preservation Technology Of Crawfish

In recent years,with the continuous improvement of China’s national economy and consumption level,crawfish products with delicious flavors,unique flavors and rich nutrition are increasingly welcomed by consumers.However,the main marketing method of crawfish products is ready-to-sale at present,which is susceptible to the impact of the crawfish breeding cycle,and resulted in,leading to unmet consumer demand for the convenience and storage stability of crawfish products.Firstly,The fresh crawfish were used as raw materials in the present study,the modern food processing technology was employed,and the process parameters of marinated crawfish were optimized to prepare marinated crawfish with a unique flavor,rich in nutrition,and convenient to carry.Secondly,the various preservation methods of marinated crawfish were compared,and a shelf life prediction model for marinated crawfish was also established,which provides a theoretical basis for longer-term storage of marinated crawfish.The effect of heating,cooling and marinating on the quality of crawfish was studied.The results show that the heating effect of microwave was better than cooking and frying in the crawfish heating process,and the optimal microwave heating time was 150s.The vacuum cooling effect was better than forced air cooling and natural cooling in the crawfish cooling process,and the optimal vacuum cooling termination temperature was 20°C.Soaking in 5°C brine for 4.5h was the best process condition for marinating of crawfish.The effects of quick-freezing,modified atmosphere,irradiation,and biological preservatives on the quality of marinated crawfish during storage were studied.The results showed that the shelf life of marinated crawfish was 296 days at-18℃.When the marinated crawfish was treated by modified atmosphere before storage at 10°C,the shelf life of marinated crawfish was about 18 days as the atmosphere composition of 75%N₂+25%CO₂was used.As the marinated crawfish was irradiated with high-energy electron beam,the unpleasant flavor was generated in the package,and the shell of crawfish had an uneven yellow color,which resulted in an unacceptable level of sensory quality of marinated crawfish.Therefore,it was concluded that the marinated crawfish was not suitable for irradiation treatment.The shelf life of the marinated crawfish which treated by biological preservative at10°C was about 11 days.The combination analysis of each storage method was carried out.After screening,the feasible combination was determined as:frozen preservation agent+biological preservation agent,gas adjustment preservation agent+biological preservation agent.The regression equation between the change rate constant k and storage time（d）was established by mapping the variation curves of TVB-N value and total numbers of colony of marinated crawfish during storage time was investigated,and the regression equation between TVB-N value and total colony change rate constant k and storage time（d）was also established,and therefore the activation energy Ea and the pre-finger factor k0 could be calculated.Therefore,the Arrhenius equation of TVB-N value change rate constant k and storage temperature T was finally established.The shelf-life prediction model of the TVB-N value and the total number of colonies of the combination of quick-freezing+biological preservative were SL=ln(B_TVB-N/B_TVB-N0)/[7.75×10⁸exp（-5.4×10⁴/RT）]and SL=ln(B_{total number of colony}/B _{total number of colony 0})/[2.05×10¹⁰exp（-5.9×10⁴/RT）],respectively.The theoretical shelf life with storage condition of-18℃was calculated about 320.78 days and 328.17 days,respectively.The absolute deviations of the two shelf life prediction models from the actual value of 317days were 3.78 days and 11.17 days,respectively.The shelf life prediction model of the TVB-N value and the total number of colony of the combination of modified atmosphere+biological preservative were SL=ln(B_TVB-N/B_TVB-N0)/[4.16×10³exp（-2.57×10⁴/RT）]and SL=ln(B_{total number of colony}/_{total number of B colony 0})/[9.92×10³exp（-2.5×10⁴/RT）],respectively.The theoretical shelf life with storage condition of 10℃was calculated about22.45 days and 23.13 days,respectively.The absolute deviations of the two shelf life prediction models from the actual value of 20 days were 2.45 days and 3.13 days,respectively.The results indicated that the two prediction models could accurately predict the shelf life of marinated crawfish,and the shelf life prediction model of TVB-N was better than that of the total number of colony.