The Effecs Of Marinating And Sterilizing Processes On The Qualities Of Canned Skipjack

In this study, skipjack was used as raw material, optimized the sterilizing and marinating processes to improve the quality of canned skipjack. Firstly, tested the raw skipjack’s qualities, the results showed that lead, chromium, total mercury contents of the raw skipjack were qualified. So the skipjack can be made into canned food. Suitable salting process can improve the quality of canned skipjack. After being pickled fish should take off some water, get a certain amount of salt, to inhibit microbial growth and to improve the hardness of the fish in order to facilitate subsequent processing. Measured the weight loss of fish meat in saline with concentrations of 15%, 20%, 30%, fish meat was found to lose weight only in saline of 30%. Using Box-Behnken response surface design method designed the optimizing experiments of pickling process and mathematical model of salinity fish marinated relationship between salt concentration, pickled temperature, marinated time. According to the mathematical mode and three restrictions which were saline with concentration of 30%, decrease pickled temperature and salt content of marinated fish meat was about 5%, the ideal marinated time was 29 mins. Then compared the optimized and initial salting process’ s effects on the texture properties and sensory qualities, the results showed that the optimized salting process was better.Optimized the constant-retort-temperature(CRT), required the heat strength of sterilizing process to be enough to kill six Log Periodics of Bacillus stearothermophilus and Clostridium botulinum, got the sterilizing times under different sterilizing temperatures according to the sterilizing formula, finally set four CRT methods which were CRT1:temperature was 115℃, time was 80mins; CRT2:temperature was 118℃, time was 40mins; CRT3:temperature was 121℃, time was 10mins; CRT4:temperature was 125℃, time was 8mins. Compared the canned skipjack samples sterilized by different CRT methods in terms of texture, color, TVB-N, soup turbidity, crude protein content in soup, muscle fibers’ structures under scanning electron microscope and sensory qualities, the results showed that sample sterilized by CRT3 had better texture, clearer soup, low crude protein content in soup, smooth muscle fibers’ structures and best sensory quality. But not so good in color and TVB-N. In terms of all the results, CRT3 was the best constant-retort-temperature sterilizing process.Optimized the variable-retort-temperature(VRT) sterilizing process. Three types of variable-retort-temperature sterilizing processes were composed according to F0=20min then compared the two processes with constant-retort-temperature sterilizing process. Analysed the heating histories of the retorts and cool points, the results showed that the three methods have same F-value but different combinations of temperature and time. Compared with the constant-retort-temperature sterilizing process, the hardness, springiness and cohesiveness of meat increased by 22.8%, 6.9% and 20.5%; the turbidities and crude protein amounts of soup decreased by 29.41% and 48.13%; the total volatile basic nitrogen amount decreased by 20.14%. The edomysiums were less disintegrated by variable-retort-temperature sterilizing processes, as shown by observing the cross-sectional microstructure of muscle. All these results showed that variable-retort-temperature sterilizing processes can reduce the quality loss caused by sterilizing. And the best variable-retort-temperature sterilizing process was VRT3.