Analysis Of Special Spoilage Organisms And Targeted Anti Microbial Technology On Beef During Ice Storage

Beef has a high content of protein with low fat,thus it’s popular among a vast number of consumers for its delicious taste.Due to the limited storage,the quality of maintain and market shelf life become a problem to be solved.Ice-temperature storage is a new technology to keep fresh food between freezing point and 0℃.This technigue has the advantage of keeping fresh extending shelf life.This study mainly adopts beef as the experimental material,and it will be stored at ice temperature (-1±1℃).This paper studied the inhibitory effect of spices through isolation and identification of SSOs in beef during storage.The main contents and results were as follows:1.The fresh beef were respectively packaged on tray and vacuum and were stored at ice temperature.The two different types of packaging were compared by measuring the total bacterial counts,sensory quality,pH,total volatile base nitrogen (TVB-N),thiobarbituric acid reactive substances (TBARS),drip loss and other indicators during 0,1,4,7,10,15,20 days.The result indicate that,the sensory quality of vacuum packaged beef was always higher than that of tray packaged beef during ice storage,but its value of TVB-N, TBARS and pH were lower than tray packaged beef.The storage period of tray packaged beef is 15 days, while the storage period of vacuum packaged beef is 7 days. Vacuum packaging can improve the quality of beef effectively during ice storage and prolong its storage time.2.The vacuum packaged beef was stored at ice temperature(-1±1℃). We made isolation of many kinds of spoilage bacterias through selective medium (CFC medium, STAA medium, MRS medium, VRBDA medium). Then we made use of methods including isolation and culture, morphological identification,16S rDNA, et al to analysis and identify the dominant bacteria species of beef under vacuum condition stored at ice-temperature.The results showed that the spoilage bacteria which is prone to induce the deterioration of vacuum-packaged beef including Serratia proteamaculans、Rahnella aquatilis、 Brochothrix thermosphacta、Lactobacillus sakei、Carnobacterium divergens、Pseudomonas fragi, and serratia sp. and Carnobacterium sp.The research results provided a theoretical basis for the control of the vacuum packaged beef by antibacterial measures.3.The fresh beef was packaged in vacuum at ice temperature, this kind of beef was inoculated with dominant spoilage bacteria. We evaluated the natural ability of spoilage bacteria through measuring total bacterial counts, sensory quality, pH, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS) and chromatic aberration after 0,4,8,12 and 16 days respectively. The results showed that the spoilage potential of M5(Carnobacterium divergens), S6(Brochothrixthermosphacta), M2(Lactobacillus sakei) and C1 (Serratia proteamaculans) got stronger capacity in the aspect of deterioration, and therefore the four kinds of bacteria were identified as SSOs of vacuum packaged beef which was stored at ice temperature.4. The bacteriostasis effect that clove,garlic,cinnamon,ginger, anise were studied the SSOs including M5,S6 and C1 by the method of cup dish, then found the MIC values of different spoilage bacteria and regarded brochothrix thermosphacta (S6) as the testing strain to combine the five kinds of spice essential oils, and optimized the formula by orthogonal experiment. The results showed that five kinds of spice essential oils had better inhibition effect on S6, M5 and Cl,and they had the best inhibition effect on C1.Through orthogonal experiment,The optimal compound formula of five kinds of spice essential oils were obtained:clove oil 1%, garlic oil 2%, cinnamon oil 2%, ginger oil 0.375% and anise oil 0.75%.5.After treatment with compound essential oil, the fresh beef was packaged in vacuum and stored at ice temperature. The total bacterial counts, sensory quality, pH, TVB-N, TBARS and chromatic aberration of the beef were dectected respectively after 0,5,10,15,20,25,30 and 35 days, validated the antibacterial efficiency of compound oil. The results showed that the compound oil can inhibit the growth and reproduction of spoilage microorganisms in beef, and inhibit the production of MDA and nitrogenous substances. Thus it could slow down fat oxidation of the beef and the rate of protein decomposition, and made the beef obtain a wonderful smell, at the same time, to improve the color of beef. By comprehensive determination, the vacuum packaged beef treated with compound oil and stored at ice-temperature can prolong the preservation period to 25d.