Effect of processing on the quality of frozen and fresh tilapia fillet

In order to obtain the quality difference of tilapia fillets by processing,the sensory evaluation and texture analyzer were combined to study the processing of curing,solar energy heat pump drying( SEHPD) and sterilization.The results showed that the moisture contents of samples were falling after curing,while the contents of sodium chloride and salt soluble protein increased.L value of two fillets decreased significantly compared with the control group( p < 0.05). In the curing process,hardness and chewiness of two fillets increased significantly( p < 0.05). As for springiness,texture analysis indicated no significant difference in fresh fish fillets( p > 0.05) and a significant difference in frozen fish fillets( p < 0.05).The results also showed that two kinds of fish fillet exhibited a decrease in water content during drying process.The drying rate of frozen fish fillet was much faster and also the water content of frozen fish fillet decreased obviously in the initial stage,with a slowly decreased of drying rate in the later stage.The drying rate of both fish fillet decreased after drying for three hours and the dry basis moisture content of both fish fillets were nearly the same in 8 h.In addition,color analysis indicated the b value of two fillets increased significantly( p < 0.05) and a value of fresh fish fillet increased not significantly( p > 0.05),while a value of frozen fish fillet changed significantly after sterilization( p < 0.05). Except for the conglutination of fresh fish fillets and springiness of frozen fish fillets which were not changed significantly( p > 0.05),the hardness,cohesiveness and chewiness of two fillets were all increased significantly( p < 0.05). Total volatile base nitrogen content of fresh and frozen fish fillet were 14.13 and 15.11 mg /100 g respectively placed for one week after sterilization,and volatilebase nitrogen content were both in the fresh fish limited value of 30 mg /100 g. The total bacteria also was not exceeded.