Development Of Ready-to-eat Small Yellow Croaker By Low Temperature Vacuum Frying

Small yellow croaker?Larimichthys polyactis?is an important marine fish in China,with an abundant production,low price.It is favored by consumers because it is rich in various nutrients which required by the human beings.However,the current commercial products of small yellow croaker are mainly frozen and dry pickled products,which is too simple in product types to satisfy the consumers'demand for diversification,nutrition and health of modern food.In this study,a ready-to-eat small yellow croaker was developed by employing low temperature vacuum frying.The conditions of curing,deodorization,seasoning,drying temperature and time,vacuum frying temperature and time,and packaging methods of products were investigated and optimized.The study aims to develop a safe and nutritional fried conditioning product with crispy taste and low oil content.The main research contents and results are as follows:1.The curing,deodorization and seasoning of small yellow croaker were conducted by wet-curing method.By measuring the salt content,moisture content and sensory evaluation of small yellow croaker during curing,the deodorization agents was screened.The four-factor and three-level orthogonal test was performed to determine the best seasoning formula.The results showed that the better curing method was salted with 3%salt solution for 2 h.The small yellow croaker marinated by 2%onion ginger garlic+1%wine solution got a better deodorization effect.The optimum seasoning formula for small yellow croaker is 1.5%of deodorization,2%of MSG,3%of white granulated sugar,and 1%of chili powder.2.The effects of drying temperature,drying time,frying temperature and frying time on oil content,moisture content,color difference,brittleness and sensory score of vacuum fried small yellow croaker were studied by single factor experiment,and optimized by orthogonal experiment.The optimal process parameters for low-temperature vacuum fried small yellow croaker were:drying at 50?for 2 h,frying at 95?for 3500 s.The vacuum fried small yellow croaker was deoiled by centrifugation,and the best deoiling time is 300 s.3.The colorimeter,texture analyzer,electronic nose,GC-MS and other means were used to analyze the color difference,texture,oil content,moisture content,volatile flavor components and other indicators,to compare the quality difference between low temperature vacuum fried and atmospheric fried small yellow croaker.The results showed that,compared with atmospheric frying,low-temperature vacuum frying significantly reduced the oil content and moisture content of small yellow croaker,with an intact shape and good color.The two types of fried small yellow croaker differed greatly in flavor.The vacuum fried small yellow croaker was detected 21 volatile substances,among which the content of aldehydes and alcohols were relatively high.Atmospheric fried small yellow croaker was detected 14 kinds of volatile substances,among which the content of aldehydes and nitrogen-containing compounds were relatively high.4.Vacuum-fried small yellow croaker was packaged by air packaging and modified atmosphere packaging?100%N₂,70%N₂+30%CO₂?,and stored at 37?with a constant temperature.The storage characteristics were studied by analyzing sensory score,moisture content,brittleness,color difference,peroxide value,acid value,total number of colonies and flavor.The results showed that the preservation effects of modified atmosphere packaging method was superior to air packaging,and the 70%N₂+30%CO₂packaging effect was better than 100%N₂ packaging.For the atmospheric fried yellow croakers,the total number of colonies and acid prices exceeded the limit standard after stored for 25 days,which means the quality of products deteriorated seriously and wasn't suitable to eat.On the other hand,the shelf life of low temperature vacuum fried small yellow croaker was more than 60 days,which was significantly longer than that of atmospheric fried fish.