Microbial Control Technology Of Poached Chicken Under Cold Chain Sale

Several preservations, including packaging, photodynamic sterilization andpressure technology, on the shelf-life and quality of poached chicken had been studiedin this paper.The physicochemical characterization and dominant pollution microorganism ofpoached chicken from common packaging, vacuum packaging and modifiedatmosphere packaging were examined. Results showed no significant difference(p＞0.01) in water content, pH and volatile basic nitrogen in poached chicken of differentpackaging. A linear increase of total aerobic bacteria in poached chicken of differentpackaging was also observed during storage at10℃, and their growth rates weregeneral packaging＞atmosphere packaging＞vacuum packaging. Clostridium,coliform and lactic acid bacteria were not detected in poached chicken of differentpackaging during storage at10℃, and a little yeast and mold could be detected inpoached chicken of different packaging. The dominant aerobic bacteria from poachedchicken of different packaging were identified using16s rDNA sequence analysismethods. Results showed these aerobic bacteria were Pseudomonas sp.,Staphyloccocus aureus, Exiguobacterium sp. and Carnobacterium sp.. That existeddifferen between dominant aerobic bacteria in the poached chicken of differentpackaging.The sterilize properties of photodynamic based on Na-Chlorophyll was studied inthis paper. Results showed that it had a good inactivation against Gram-positivebacteria, and the optimum bactericidal concentration of Na-Chlorophyllin was10-5mol/L. However, only when coordinated with EDTA and Nisin did photodynamichave sterilization effect on Gram-negative bacteria. The results also showed thatphotodynamic had no significant effect on prolonging the shelf life of poachedchicken when used alone. What’s more, the value of L, a, b and TBA of poachedchicken after illumination had no significant difference to control ones. Theintracellular enzyme activity, cell permeability, surface and internal structure of S.aureus had been observed to inquiry the bactericidal mechanism of photodynamic.Results indicated that the activity of cell decreased meanwhile the cell wall andmembrane structure, as well as the orderly state of cell were destroyed byphotodynamic. It probably due to the reaction among the singlet oxygen produced by illumination and cellular proteins, lipids, nucleic acids or other substances in the cell,which eventually led to the death of microorganism.The changes of microbiology and quality of poached chicken before and aftertreatments of300MPa intermittent pressure,300MPa holding for6min and500MPa holding for6min had been detected. According to the results, the shelf life ofpoached chicken under high hydrostatic pressure treatments were prolongedsignificantly, while the value of L reduced and he value of a increased. Yet, nosignificant differences had been found in the moisture content, texture and TBA valuein the chicken under different treaments. It also showed that the shelf life of poachedchicken under300MPa intermittent pressure treatment could be prolonged to5days,while300MPa holding for6min was about10days and500MPa holding for6minwas more than a month, when compared with the control group. And the amount ofother microbial flora (lactic acid bacteria, Bacillus bacteria, et al) detected in poachedchicken at the end of shelf period were CM＞300MPa intermittent pressure>300MPa holding for6min>500MPa holding for6min. It was also found that the lengthof shelf life of poached chicken related to the stress and dwell time.