Effect Of Pretreatment Processes On Muscle Proteins And Histamine Variation Of Canned Skipjack

Skipjack meat has a bad taste,heavy smell,unsuitable raw,is a low-value tuna.Thus,skipjack is mainly as the raw material for the production of canned tuna.For the certain raw material,the pretreatment processes and the sterilizing process are the main factors that affect the quality of the canned product.The research of sterilizing process of canned tuna already has a certain theoretical basis and technological achievements.Choosing a appropriate sterilizing process can improve the quality of the products.Currently,optimizing pretreatment process to improve the quality of canned product is lack.Each process of the canned can have a different impact on fish muscle proteins.While the changes of the fish muscle proteins have an impact on the quality of fish meat,and considering the edible safety,the change of histamine content of fish meat also need to be concerned.So,the effect of pretreatment processes on muscle proteins and histamine variation of skipjack were studied,at the same time combined with the indexes such as color,texture,etc.The aim is to provide a reference for canned skipjack processing.1.Firstly,the effect of different thawing methods on muscle proteins and histamine variation of skipjack were studied.Frozen skipjack(-20?)were thawed by the four thawing methods(room temperature,static water,running water and 4?),then the metmyoglobin(metMb),soluble myofibrillar proteins(SMP),soluble sarcoplasmic proteins(SSP)and histamine content of skipjack meat were measured.Meanwhile,evaluations of thawing loss rate,color and texture were combined.The results indicated that thawing loss rate and chewiness with SMP content,Ca2+-ATPase activity,A-SH content;Ca2+-ATPase activity with A-SH content were highly correlation(p<0.01).4? thawing method remained the color,metMb and histamine content significantly(p<0.05),presented a better structure and functional property of myofibrillar protein,remained a lower thawing loss rate and a better texture.Overall,the better thawing method is 4? thawing method.2.Secondely,the effect of brine salting processes on muscle protein and histamine variation of skipjack were studied.The effect of different brine salting factors(brine concentration,brine time and brine temperature)on muscle myofibrillar protein and histamine variation of skipjack were studied by single tests.The results indicated that brine salting factors have a significant impact on the salt content of skipjack muscle and the protein content of brine.Considering from the least protein content of brine,better sensory evaluations and histamine content within the limit of safety,preliminary chose the best salting process: brine concentration 15%,salting temperature 10?,salting time 30 min.By accurate multi-objective optimization of salting technology,salt content of skipjack muscle and protein content of brine were chosen as response value.The results indicated that the best salting technology parameters were salting concentration 16%,salting temperature 10?,salting time 29 min,while finding that salt content of skipjack muscle and the protein content of brine with salting process parameters had a fitting polynomial model,and the fitting polynomial model can better fit the results of the experiment.3.Thirdly,the effect of frying processes on muscle protein and histamine variation of skipjack were studied.The moisture content,histamine content and collagen content of the skipjack muscle were adopted as the investigating indicators.The results were shown as follows,with increasing of frying temperature and prolonging of frying time,the moisture content of skipjack muscle decreased.Under frying temperature 150? for 2min,the moisture content of skipjack muscle was 62.23%,and under frying temperature 190? for 5min,the moisture content of skipjack muscle was least(62.23%).According to the change of the muscle moisture content,we picked out three frying processes:150? for 5min,170? for 3min and 190? for 2min,which can reach the target moisture content(55%).Collagen protein,nonprotein nitrogen,histamine content had the same change trend,with the change of moisture content on the contrary,showed a rising trend.The content of total collagen protein and histamine of the skipjack muscle had no significant difference(p>0.05)under three frying processes.Under frying temperature 170? for 3min,the content of soluble collagen protein and NPN of the skipjack muscle were fewer than the other two groups.Under frying temperature 170? for 3min,after sterilizing,fish meat had least collagen loss,remained a better texture,showed a better color,therefore,chosen as the best canned skipjack frying process.Through correlation analysis,hardness with soup protein content was significantly negative correlation(p<0.05),soluble collagen content,and its proportion with NPN content was positive correlation(p<0.05).