effects of nanochitosan with and without sodium acetate coating on pseudomonas fluorescens and the quality of refrigerated rainbow trout filets

The present study was conducted to evaluate the effects of nanochitosan with sodium acetate and none-sodium acetate coating on pseudomonas fluorescens and the shelf life of refrigerated rainbow trout (onchorhynchus mykiss). 45 samples of rainbow trout filet in five positive and negative treatments including a control, 1% nch(t2), 2% nch(t3), 1% nch+5% naoac1 (v/v, t4), 2%nch2%+ 5%naoac1(v/v,t5), the negative groups incubated by p. fluorescens bacteria (pf+nch (1 and 2%) +5% naoacl (v/v) (pf+nch(1 and 2%)) and a negative control during the 16 days. comparisons of microbial, chemical and sensory analyses were purely done on safe treatments periodically using one way anova and duncan tests. results detected significant differences between the control group and both nch+5% naoac1 (v/v), and nch free of 5% naoac1 (v/v) in all amounts of microbial and chemical indices (p<0.05) and there were no significant differences between the two nch groups (p>0.05). sensory indices illustrated that filets treated with each groups of nch±5% naoac1(v/v) received good points and their shelf life was 16 days, but control group settled in this status on sixth day of the test. for the two other treatments, shelf life storage increased and remained on 12 th and 16 th day, respectively. furthermore, third day of the test showed high amounts of bacteria in the pf incubation treatment. high levels of bacteria same as that in the control group were determined on sixth day in desirable samples and in nch+ p. fluorescens, while there was an obvious bacterial reduction in bacterium mixed with nch+naoac and kept for 12 days. overall, utility of nch+naoac increased the shelf life in refrigerator storage and decreased the amount of p. fluorescens in it.