Study On The Application Of Ultrasound And Enzymes In Semi-dried Sea Bass Processing

Sea bass is rich in protein,with tasty meat and fewer bone spines.Cured sea bass is popular among consumers as one of the main processing methods.However,the current cured fish has problems such as long curing time,high salt content and poor sanitary conditions of the products,which can’t meet the requirements of modern consumers.Therefore,in this paper,a semi-dried sea bass product was studied by dry curing and dehydration,ultrasonic wet curing,enzymatic digestion and dry processing of the fish blocks using sea bass as raw material.On this basis,the flavor substances in fish pieces without and with the addition of exogenous enzymes were studied,together with the shelf life of semi-dried sea bass at 20°C.The main findings of the study were as follows.The moisture content,salt content and volatile salt nitrogen(TVB-N)content were used as indicators to determine the dry curing and dehydration time of the fish blocks for 13 h.The ultrasonic power was determined to be 420 W and the ultrasonic time was determined to be 50 min,using salt content and sensory score as indicators.The optimal conditions for enzymatic digestion of fish blocks were obtained by response surface optimization with hydrolysis degree,free fatty acid content and sensory score as the indexes,enzymatic digestion time of 5 h,enzymatic digestion temperature of 45℃,solution salt concentration of 5%,flavor protease addition of 62.5U/g and neutral lipase addition of 50 U/g.Using the drying rate and sensory score of fish pieces as indicators,the drying temperature of fish pieces was determined to be 55°C and the drying time was 4.5 h.The effects of drying temperature on the sensory score,thiobarbituric acid value(TBA),TVB-N,texture and color difference of fish blocks showed that the TBA,TVB-N,texture and color difference increased with the increase of drying temperature,and the sensory score showed a trend of increasing and then decreasing.The flavor substances of the fish pieces without and with the addition of exogenous enzymes were determined using gas chromatography-mass spectrometry(GC-MS).The results showed that there were 29 flavor substances in the fish pieces without the addition of exogenous enzymes and 52 in the fish pieces with the addition of exogenous enzymes,and that the aldehydes,ketones and alcohols in the fish pieces increased with the addition of exogenous enzymes.The physical and chemical parameters of semi-dried sea bass at the three storage temperatures(-18°C,4°C and 25°C)varied significantly,with the quality of the fish pieces at-18°C being significantly better than at 4°C and 25°C.According to the shelflife prediction model,the shelf-life of semi-dried sea bass stored at 20°C was 18 d.