Study On The Dynamic Changes Of Microbial Flora In Catering Waste On Early Stage Off Tables And Bacteriostasis Experiment

In China, the production of catering waste represents a significantly fraction of municipal solid waste. Catering waste is rich in nutritional ingredient and is an important feed resource with great potential. No odor, no discoloration, without large number of abnormal air bubbles, no large amounts of water and debris and p H in 4~7 were the standard for judge the available catering waste in recycling companies. The state of catering waste from production, collection, storage and transportation to processing for feed is uncontrollable and unknown. The quality assurance of raw materials is the critical control point during the catering waste for feed processing. The study on microbial changes in catering waste and making the storage period before processing in a controllable state, can provide reliable materials for the use of feed utilization and provide the basis for safety assessment of catering waste. The study can also provide the basic data for other biological treatment technologies and promote the development of the resource utilization of catering waste.(1) The detection of bacteria pollution in industrial collection catering waste and the simulative collection catering waste. The experiment of freeze-dried catering waste replace fresh catering waste for microbiological determination was studied. No significant difference between fresh and freeze-dried catering waste was found in total bacterial count(P>0.05). Freeze-dried sample was used to instead of the fresh sample for microbiological determination. The catering waste was lyophilized to reduce the damage effect of thawing on bacterial. Crushed the freeze-dried samples can improve the homogeneity of the sample and improve experimental repeatability and accuracy.Classify the catering waste into rice noodle type and meat dish type and process the catering waste under 30 ℃and 10 ℃. Three parallels were selected in every processed methord for total bacteria detection. The initial total bacterial count of the industrial collection catering waste that 10~12 h after getting off the table is about 107cfu/g. And the total bacterial count of catering waste is stable fluctuating between 107 cfu/g and 108 cfu/g both under 30 ℃and 10 ℃. The bacterial contamination of inderstrial collection catering wasfe is relatively higher after the transportion. No obvious increase process in processed time points. The effect of environment temperature and matrix condemiation ingredient on total bacterial in catering waste is also not obvious. In the simulative collection catering waste that off the table about 2 hours, the bacterial contamination is relatively lower and an increase stages of microbial growth was presented. The environment temperature effect total bacteria obviously. Total bacterial count of catering waste reached 107 cfu/g after 12 hours under 30 ℃ and after 44 hours under 10 ℃, then fluctuated between 107 cfu/g and 108 cfu/g stably which consisted with the results of the industrial collection catering waste. And the maximum value of total bacterial are relatively at the same range. That means the maximum was not affected by the matrix components and temperature. The two type samples may have different in species but in same total numbers.(2) Fresh samples of industrial collection and simulative collection catering waste at 0 h point and 72 h time point under 30 ℃ were selected to detect the pathogenic bacteria: Salmonella, Shigella Castellani and Staphylococcus aureus. Three kind of pathogens were not detected in industrial collection and simulative collection catering waste at 0 h time point. The catering waste used in our experiment were not infected with the three of pathogens during the transportion. The detection of the three types of pathogens in catering waste at 72 h time point under 30 ℃ were negative. Although the experiment condition were not germfree, no pollution of the three kind of pathogens during experiment processing.(3) Denaturing gradient gel electrophoresis(DGGE) of amplified fragments of genes coding for 16 S r DNA was used to study the development of bacterial communities during decomposition of catering waste. The time pint of 0 h, 12 h and 72 h under 30 ℃ and 0 h, 44 h, 96 h under 10 ℃ were selected to analyze the variation of dominant bacteria in catering waste. The dominant bacteria in meat dish type catering waste and rice noodle type catering waste is different but no obvious. The main dominant bacteria in the two type catering waste are both Weissella, and Streptococcus. The alteration of dominant bacteria species in stable growth phase of total bacteria is not obvious. From the catering waste off the table to stable growth phase is the phase of the significant alteration of dominant bacteria species. Temperature conditions affect the species of dominant bacteria in catering waste. Under 30 ℃, dominant bacteria contain Lactobacilli and Pseudomonas, while under 10 ℃ include Pseudomonas and Brochothrix thermosphacta.(4) The bacteriostasis effect of negative ions waste bin(8000/cm3) on catering waste. The discrepancy of total bacteria count and dominant bacteria populations in catering waste between negative ions waste bin and general waste bin was studied. No significant difference was found on the alteration of total bacteria of catering waste between the general waste bin and negative ions waste bin under 30 ℃. There is no obvious difference in dominant bacteria populations between the general waste bin and negative ions waste bin, at the same time point in the same type catering waste. The inhibition of negative ions waste bin(8000/cm3) to total bacteria and dominant bacteria in catering waste do not achieved the expected result. But the negative ions waste bin(8000/cm3) can reduce odors during catering waste processing.