Structure Formation And Process Optimization Of The "Garlic Clove-Like Fish" In Conditioned Fish Fillets

Under the background of the rapid development of new retail and new catering,prefabricated aquatic products have become a hot consumption spot of Chinese residents.The important evaluation indicators to measure the quality of prefabricated fish products include the tissue structure,texture characteristics,and flavor quality of fish,which directly affect the acceptability of consumers.After conditioning,freezing,and cooking,fish can form a“garlic clove-like”structure and exhibit a good taste.Therefore,the description of“whether the fish forms a unique garlic clove-like structure”have widely been used in the sensory evaluation of conditioned fish products.However,little literature reported on the structural characteristics,formation mechanism,influencing factors,and evaluation methods of the“garlic clove-like fish”structure.Consequently,grass carp was used as the research object in this study,and the effects of conditioning treatment conditions,fish species,endogenous enzyme activity,and other factors on the structure,texture,and taste of conditioned fish products were studied.The characteristics,forming conditions,and influencing factors of the"garlic clove-like fish"structure of conditioned fish products were clarified.Moreover,the evaluation and regulation method of the"garlic clove-like fish"structure was established.This study can provide a theoretical and technical support for the development of high-quality prefabricated conditioned fish products.The main findings are as following:1.Characterization and evaluation of the structure of the"garlic clove-like fish"in conditioned fish products.Grass carp was used as the research object in this study.Twelve fish fillets with different degrees of conditioning were prepared by controlling the amount of salt added,conditioning temperature,and conditioning time.The structural characteristics of"garlic clove-like fish"of conditioned fish fillets were described by sensory attribute description,texture profile analysis,and tissue structure characteristic analysis.The evaluation method of the"garlic clove-like fish"structure was established.The results showed that there were significant differences in the sensory scores,texture properties,and tissue morphology of the 12 groups of the prepared conditioned fish fillet samples.The results showed that conditioned grass carp fillets with a typical"garlic clove-like fish"structure could be prepared by controlling the amount of salt added,conditioning temperature,and conditioning time during conditioning.It was concluded that the"garlic clove-like fish"structure was a special structure after steaming the conditioned fish fillet.The appearance of this structure showed that the fish fillets were completely separated from each other,the layers were smooth and free of burrs,the taste of the fish was smooth and tender,and the color was bright.The sensory score of the"garlic clove-like fish"structure of conditioned fish fillet was positively correlated with texture parameter recovery value,adhesion value,and intermuscular distance(p<0.01),and negatively correlated with myofibril area(p<0.01).The texture and tissue structure parameters of conditioned fish fillet with excellent"garlic clove-like fish"structure are as follows:hardness 2600g~3300 g,springiness 0.56~0.74,chewiness 600 g~1300 g,resilience 0.24~0.32,adhesiveness 240 g·sec~350 g·sec,muscle fiber area 24000μm~2~32000μm~2,intermuscular distance 16μm~21μm.2.Formation conditions of the"garlic clove-like fish"in conditioned fish products.Grass carp,silver carp,bighead carp,crucian carp,mandarin fish,and bluntnose black bream were used as the research objects,and the effects of salt addition,conditioning time,and freshwater fish species on the taste,texture,tissue structure,and physicochemical indexes of conditioned fish fillets were studied by means of microphotography,histochemistry,texture analysis,and sensory evaluation.The conditions for the formation of the structure of"garlic clove-like fish"in fish fillets were clarified.The results showed that salt addition,conditioning time,and freshwater fish species had significant effects on the structure,sensory quality,texture,and tissue structure of"garlic clove-like fish".A proper salt conditioning treatment could promote the formation of the"garlic clove-like fish"structure of the conditioned fish fillet,which presented a good taste,an obvious separation between muscle fiber bundles,and a high sensory score of the"garlic clove-like fish"structure.Among the six kinds of freshwater fish,mandarin carp,grass carp,and bighead carp could form a nice"garlic clove-like fish"structure,while silver carp,crucian carp,and bluntnose black bream were difficult to form the"garlic clove-like fish"structure after conditioning.Histological and histochemical results showed that the conditioned fish fillet with a typical"garlic clove-like meta"structure had high calcium concentration and calpain activity,large space between muscle fiber bundles,and complete separation of Z-disk.Correlation analysis showed that the sensory score of the"garlic clove-like fish"structure of conditioned fish fillet was positively correlated with the appearance score,taste score,spaces between myofibrils,and Na Cl content(p<0.05),but negatively correlated with the myofibril bundle area,calcium concentration,and calpain activity(p<0.05).The sensory score,calpain activity,and water content of the conditioned fish fillets could be used to optimize the process parameters to regulate the structural quality of the"garlic clove-like fish".3.Optimization of processing technology of conditioned fish products based on the structural quality of"garlic clove-like fish"Grass carp was used to investigate the effects of salt addition,conditioning temperature,and conditioning time on calcium-activated protease activity,water content,and structural sensory score of the"garlic clove-like fish"by a quadratic orthogonal rotation combination experiment,and an evaluation model for the"garlic clove-like fish"structure was established.Furthermore,with the goal of sensory score,calpain activity,and water content,the conditioning process parameters were optimized by the response surface analysis.The optimum conditioning conditions were as follows:salt 4.5%,conditioning temperature 4℃,conditioning time 3 d.Under these conditions,the activity of calpain in the conditioned fish fillet was 126.77 U/g,the water content was 71.92%,the structural sensory score of the"garlic clove-like fish"was 8.90.By adjusting the amount of salt addition,conditioning temperature and conditioning time,the calpain activity and water content in conditioned fish fillet could be controlled,promoting the formation of the"garlic clove-like fish"structure in the conditioned fish.