Ready-to-eat Dried Shrimp Processing Technology And Shelf Life Prediction

Penaeus vannamei is rich in nutrients and perishable after fishing.Apart from a small portion of fresh food,Most of them are preserved by quick freezing method.High energy consumption,single product and low added value,it is difficult to meet market demand.Penaeus vannamei were used as raw material in this study.The ready-to-eat dried shrimp products was developed by the combination of blanching process and solar drying process,and the shelf life of the product was predicted.In order to provide theoretical basis for high value utilization of Penaeus vannamei.The main results are as follows:1.The appropriate processing conditions for the instant blanching of ready-to-eat dried shrimp and the solar drying process were determined.The blanching process and the solar energy drying process were used to cook and dry the shrimp,orthogonal test optimization was performed on the basis of single factor tests,respectively.The suitable processing conditions of blanching process were determined as follows:cooking time was 70 s,the concentration of salt water was 3%,and the water ratio was 1:1.5.The suitable processing conditions of solar drying process were determined as follows:Solar drying temperature was 55℃,the dry wind speed was 8 m/s,and the load was 3 kg.2.The nutrients and volatile flavors of ready-to-eat dried shrimp were analyzed.The content of water,crude protein,crude fat,and crude ash of ready-to-eat dried shrimp were 19.78%,61.31%,2.78%,and 4.93%,respectively.The amino acids in the ready-to-eat dried shrimp were determined,with essential amino acids（EAA）and non-essential amino acids（NEAA）accounting for 38.02%and 51.60%,respectively.The ratio of EAA/NEAA is 73.69%,which constitutes the proportion of high quality protein standards regulated by FAO/WHO.The content of calcium of ready-to-eat dried shrimp was 920 mg/kg.49 kinds of volatile flavor substances of ready-to-eat dried shrimp were identified,including 14 kinds of heterocyclic compounds,10 kinds of aromatic compounds,5 kinds of ketones,4 kinds of alcohols,5 kinds of aldehydes,4 kinds of alkane,and 2 kinds of olefins,one kind of sulfur compound,one kind of carboxylic acid,one kind of amine,and two kinds of other species.3.The changes of physicochemical,microbiological and sensory quality of ready-to-eat dried shrimp during storage at three different storage temperatures（4℃,20℃,40℃）were studied.The pH,color difference value（△E*）,volatile base nitrogen（TVB-N）and total number of colonies of the ready-to-eat dried shrimp at each storage temperature showed an upward trend,and the water content,water activity（Aw）,hardness,elasticity,chewiness and sensory scores showed a downward trend.The shelf-life of ready-to-eat dried shrimp at three storage temperatures of 4℃,20℃and 40℃was 130 d,30 d and 6 d,respectively.The volatile flavors of the ready-to-eat dried prawns before storage and after they reached the end of shelf-life at 20℃were determined.Compared with pre-storage,the percentages of flavor substances such as alcohols,amines and aldehydes increased significantly（P<0.05）,and the percentage of heterocyclic compounds decreased significantly（P<0.05）.4.A shelf life prediction model for ready-to-eat dried shrimp was established.Pearson correlation analysis showed that TVB-N had the highest correlation with sensory scores in physiochemical and microbiological indicators of ready-to-eat dried shrimp.With TVB-N as a key indicator,combined with the Arrhenius equation to establish a shelf life prediction model for ready-to-eat dried shrimp.In the prediction model,the activation energy Ea is 59.417 kJ/mol,and the pre-exponential factor k₀ is 4.71×10⁹.The shelf-life prediction model was validated by using the measured shelf life of the ready-to-eat dried prawn stored at 10℃,20℃and 30℃.The experimental results show that the relative error between the predicted value of the model and the measured value of the shelf life is within10%,indicating that the prediction model has a higher degree of fitness.This study has improved the processing technology of dried products of Penaeus vannamei,increased the added value of Penaeus vannamei products,and provided a theoretical basis and technical support for the high value utilization of Penaeus vannamei.