The Effect Of Cooking Heat Treatment Technology On The Quality Of Squid Meat

Skipjack tuna(Katsuwonus pelamis),as one of the important economic species of tuna,comprises more than 48% of the total production of the tuna.Tuna processing industry has developed rapidly in our country,and many processing enterprises usually model frozen tuna meat into fish fillet,then export to some European and American countries as the raw material of canned tuna.Thawing and steam cooking are key processes in tuna fish fillet processing and directly affected the product quality of fish fillets.In the present study,the quality of skipjack tuna changing in the heat treatment processing were studied according to the actual situation in enterprises,The main results and conclusions are as follows:(1)The effects of two thawing methods,water thawing and air thawing,on the quality of skipjack tuna were studied.Results showed that air thawing needed much longer time than water thawing.The K value,total colony number,total volatile basic nitrogen(TVB-N)and thiobarbituric acid value(TBA)of skipjack tuna meat thawed by air thawing were all higher than that by water thawing.Moreover,skipjack tuna meat thawed by air thawing showed good textural properties and high salt content.Compared to the skipjack tuna meat of air thawing,meat of water thawing represented better color,lower pH value and higher moisture content(1~2%)after cooking.(2)Quality changes of skipjack tuna during the two different cooking(T1,T2)processes were studied.The results showed that the yield of fish fillet in T1 was1~2% higher than T2.The steam cooking time of T1 was relatively 6-8 min shorter than that of T2,and the cooking loss of T1 was lower than that of T2.The color change of T1 was smaller,and also the salt content of the final product was relatively lower compared with T2.Moreover,the textural properties of skipjack tuna meat of T1 were better than that of T2.Compared to T1,the process of T2 was simpler and the total processing time was 20-30 min shorter.The fish fillet obtained by T2 was18mg/kg lower in histamine content,and higher content of non-protein nitrogen and relatively strong odor compared to T1.So,the two steam cooking technologies have their own advantages,manufacturer can select the appropriate one to produce fish fillets according to their conditions and the freshness of skipjack tuna.(3)The quality characteristic of ordinary and dark muscle of skipjack tuna after cooking were compared and analyzed.The results reflected that the water content and crude fat content of ordinary muscle in skipjack tuna were lower than that of dark muscle,and protein content was higher than that of the dark muscle,while no obvious difference was found for ash contents(P>0.05).L* and b* values of ordinary muscle in skipjack tuna were higher than that of the dark muscle,while a* value was lower than dark muscle.Moreover,the hardness,cohesiveness,elasticity and chewiness of ordinary muscle in skipjack tuna were better than that of the dark muscle.Total 43 volatile compounds were detected in the ordinary muscle and dark muscle.It could be found that ordinary muscle contains more alcohols and aldehydes,while dark muscle contains more ketones and acids.Among,many volatile flavor compounds proved as inherent flavor compounds in fishy products,such as 1-penten-3-ol,benzaldehyde,and pentadecane,were identified in ordinary muscle..