| Because of good eating quality and high nutritional value, chilled beef is welcomed by the consumers, but if the beef is contaminated by the microorganism, its shelflife will be shorten and increase the safe risk, which limit development of Chinese beef manufacturers to tend healthy and rapid. The initial number of colonies is the decisive factor on shelf life of chilled beef. Dehairing operation and the contact surface about cross-contamination is the main source initial microorganism of chilled beef. Season, working hours, carcass processing sites and processing stages will also affect the microorganism of cooling beef, so exploring reasonable spraying measures on the reduction bacteria of carcass and disinfection methods about the contact surface are of great significance to the development of cooling beef industry.This study is to explore the relationship between visual cleanliness of hide and carcass microbial contamination. Season, working hours, carcass processing sites, the measures about cleaning and disinfection on contact surfaces having an effect on chilled beef microorganisms were surveyed. Furthmore, reasonable spraying methods for carcass and disfection methods for contact surface were also researched. The results as follows:1. Hide visual cleanliness had a positive correlation with the number of microorganism on hides and carcasses. Increasing dirt on cattle was associated with higher TVC and ECC on carcasses and hides.The wet cattle transfer more microorganisms to the carcass. Hide and carcass associated with the wet cattle had higher ECC than dry cattle. Because of the lying position, brisket and abdomen about hide were seriously polluted, so when we dehaired, we should keep caution to the parts.2. The number colonies on carcass in summer were more than it in winter. Carcass and sirloin were most polluted after working one hour. The number of microorganism tended to reduce after one hour.3. The microorganism number tended to rise obviously in the breaking room. The number of microorganism following up operation tended to a stability state. Cleaning and disinfection the company contact surface after 12h or hungry after 36h, the microbial mumber of the contact surface was still unacceptable and needed to be improved. After the end of production, the contact surface pollution had little relationship with the slaughter capacity but the initial number of colonies.4. After spraying 15min, multiple sequential spraying had the same effect to hot water spraying which could reduce the largest number of colonies, pseudomonas, lactic acid bacteria, and coliform. After the most effective spraying, two approaches decreased TVC by 1 lg(CFU/cm2). After 24 hours, the residual lactic acid could continue to be effective and furtherly reduced carcass microorganism.5. The brisket was the most polluted and back polluted lightest. Hot water spraying could reduce all parts of carcass obviously.2% lactic acid spraying made the number of neck increase, but after 24 hours, the number of microorganism on neck and hip leg tended to be the same with the treatment of hot water.2% lactic acid spraying had a poor effect on the microorganism of back.6. Carcass spraying had no effect on dry loss of carcass and the overall appearance of the carcass, but would make the meat on both sides of the carcass tend to browning. If hot water sprayed long time, carcass would be damaged.74? and 83? hot water had the same effect on the microorganism of carcass.7. Cleaning had no effect on the conveyor belt because of structure.4.5 ‰ of peracetic acid could reduce the most bacteria on the boning board made of polyethylene.1:20 (v/v) Quaternary ammonium compounds had the most significant effect on the conveyor made by rubber material. Preventing corrosion of stainless,1:20 (v/v) quaternary ammonium disinfectant was the best choice. |
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