| The north pacific ocean squid stores at 0,5,10,15 ℃ were quantitatively investigated by sensory, color, texture, TVC,Psychrobacteria, Pseudomonas and TVB-N,to explore and analyze its quality changes and shelf life in different storage temperatures as well as the correlations among these indicators. Both qualitative and quantitative tests were used for Bacterial composition at initial point, the end of high quality life and shelf-life by using the simple phenotype and the Sensititre identification of bacteria system. The specific spoilage organism growth model and shelf life prediction model were build, according to the growth changes of specific spoilage organisms of the north pacific ocean squid during low-temperature storage. And then evaluate the veracity of shelf life prediction model. The results are as follows:(1) The north pacific squid samples stored aerobically at 0, 5, 10, 15℃ showed high quality within 360, 239, 96, 47 h, respectively, and shelf lives of 525、286、147、86h. During storage in different temperatures, a* value was not notable, L* value and b* value were showed increasing trend, maximum shear force and chewiness were increased first and then decreased. Averagely, TVB-N, at the ends of better-quality periods and shelf lives at the above storage temperatures were(17.15±0.31),(30.06±0.92)mg/100 g,TVC(5.89±0.40),(8.33±0.30)lg(CFU/g),Psychrobacteria(5.61±0.5),(8.36±0.23)lg(CFU/g),pseudomonas(5.23±1),(7.58±0.57) lg(CFU/g),respectively. According to the correlation analysis, TVB-N, TVC and pseudomonas as quality indicators of the north pacific squid in low temperature storage had a good consistency with sensory evaluation, the correlation between psychrobacteria and pseudomonas was significant(r>0.9).(2) The researches show that the bacteria flora of squid is complex at initial storage,and 91.48% of them were gram negative bacteria,4.26% were gram positive bacteria.The predominant bacterial flora were composed of Aeromonas spp.(27.66%),Chryseomonas luteola(23.40%), Pseudomonas spp(17.02%). In addition, a certainproportion of Acinetobacter lwoffii, Pantoea agglomerans were also detected. During the aerobically storage of 0, 5, 10, 15℃,the bacteria flora became gradually simple and the growth trend of Pseudomonas spp. were apparent,also the squid samples showed high quality within 360, 239, 96, 47 h, respectively, and shelf lives of 505, 312, 168, 80 h. Averagely, TVBN was(17.15±0.29)mg/100 g, TVC( 5.89±0.40) Lg CFU/g and Pseudomonas spp were 84.09%、72.09%、65.52% and 76.36% respectively at the end of good quality at 0, 5, 10, 15℃, and the average percentage of Pseudomonas spp. were75.92%. At the end of shelf life at 0, 5, 10, 15 ℃, TVBN and TVC were(30.05±0.92)mg/100 g,(8.33±0.30)Lg CFU/g, Pseudomonas spp. has reached 93.24%、90.53%、88.57% and 81.95% respectively, and the average percentage of Pseudomonas spp. was 87.63%. Therefore, Pseudomonas spp. was the predominated spoilage bacteria of squid stored from 0 to 15℃.(3) The growth kinetics model of pseudomonas of the north pacific squid was built by the growth kinetics of pseudomonas and Belehradek equation was:? ?? ?? ?? ?? ? ? ?? ?? ?002209.14 lg lg lg0.0158 6.95 2.718 1exp exp 1lg 9.14 0.0081 12.44 N t N N Tt N T? ? ?? ? ? ?? ? ? ?? ? ?? ? ? ?? ?? ?? ???? ? ? ?? ?Accroding to pseudomonas growth modle, the remaining shelf life(SL) could be gotten through the generation time between the initial numbers bacteria(N0) and the minimum numbers of spoilage bacteria(Ns). The SL model for the north pacific squid stored aerobically at 0-15℃ is described as follows:? ?? ?? ?? ?? ?? ?20 02010.0081 12.447.4 lg 8.0 lgln ln 12.718 0.0158 6.957.4 lg SL T N N TN? ?? ? ?? ?? ? ?? ? ? ??? ? ? ?? ? ??? ? ? ?The accuracy validation of built growth kinetic models and remaining shelf life prediction model was compared with experimental development of pseudomonas grown on the north pacific squid at temperature 4℃and 8℃.Relative errors between predicted and observed μmax, λ and SL were 16.33%,-1.31-15.68% and-2.67% respectively at 4℃,8.88%,7.04% and-15.68% respectively at 8℃,the results indicating that microbial growth models built in our research were valuable for rapid and realistic prediction of the quality and remaining shelf life of squid under aerobic storage in 0-15℃. |
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