Technology Of Oxygen-limited Heat Pump Drying Semi-dry Saury And Its Effect On Lipid Oxidation Of Products

Saury is one of important economic and fishery resources,due to its delicious tasty,high nutritional value and large annual production.The development of semi-dried saury not only facilitates storage and transportation,but also increases the variety of saury products,providing consumers with more choices.It is susceptible to lipid peroxidation during processing because the lipid content of the raw saury is high,especially rich in polyunsaturated fatty acids,which affects nutritional value and taste of product.The objectives of this study were to study the fat oxidation problems and solutions in the process of semi-dry saury production and storage.The following aspects were investigated:(1)Effects of thawing methods on quality of frozen saury under room temperature air condition,room temperature vacuum condition,flowing water condition,flowing water vacuum condition,cold air condition,cold air vacuum condition,low temperature air condition and low temperature vacuum condition were analyzed.The thawing time,thawing loss rate,acid value,peroxide value,thiobarbituric acid value,volatile base nitrogen and other indicators were determined.The results showed that products with the least oxidation level and thawing loss rate were obtained under cold air vacuum condition which was then the optimum condition.(2)Effects of brining and dry salting on salt content,acid value,peroxide value,thiobarbituric acid value and sensory quality of the saury were studied.The results showed that saury has lower degree of lipid hydrolysis and oxidation,low salinity of 3% and high sensory score after brining process with 20% salt content and 24 min pickling duration.(3)The moisture content,acid value,peroxide value,thiobarbituric acid value,fatty acid content,volatile base nitrogen,color indicators,and sensory evaluation indicators of semi-dry saury were investigated by three methods: hot air drying,conventional heat pump drying and oxygen-limited heat pump drying.The results showed that semi-dry saury has the lowest level of oxidation and hydrolysis,the highest content of EPA and DHA,bright appearance and high evaluation grade after oxygen-limited heat pump drying.(4)The acid value,peroxide value,thiobarbituric acid value,volatile base nitrogen and sensory evaluation of low-salt and semi-dry saury with treatments of addition of different antioxidants and vacuum packaging technology were analyzed during storage.The results showed that the treatment group containing 0.05% TBHQ peanut oil with vacuum packaging had the best anti-oxidation effect.