Isolation?identification And Control Ofmicroorganisms In Egg Curd

Egg curd is a common food on the market in China,its flavor is popular,but because of its raw materials-eggs,nutritious easy to be polluted by microorganisms and deterioration.Through the investigation of a egg curd factory in Changsha,it was found that the rotten rate of the egg curds in vacuum packaging was still as high as 30%in summer after high temperature and high pressure sterilization.The deterioration phenomenon is:normal egg curd with turbid soup,slightly discolored egg curd with turbid soup,completely discolored egg curd,and completely discolored egg curd with expansion package,which seriously affects the food safety and the reputation of manufacturers.In this paper,the physical properties of rotten egg dry were determined by texture TPA,the main rotten microorganism in egg dry was isolated and identified by dilution plate separation method,and the main rotten microorganism was traced.At the same time,several safe and efficient preservatives were selected for compounding,and their antibacterial effects on the isolated microorganisms were explored.The results showed that:According to the determination of TPA,total number of colonies and coliform group,the egg curds with normal color and turbid soup surface in the unqualified egg curd products were unqualified products,and the egg curds with other deterioration were deteriorated due to microbial contamination.After preliminary isolation and purification,two strains of bacteria were obtained.The two strains were the main spoilage bacteria which caused the spoilage of egg curds.The spoilage bacteria were Bacillus licheniformis.and Bacillus sp.LAMI 002.Antibacterial tests showed that?-polylysine,lysozyme,and nisin were effective in inhibiting the growth of spoilage bacteria and had a strong inhibitory effect on the growth of Gram-positive bacteria.Response surface methodology was used to determine the optimal formulation of the compounded preservatives:lysozyme 0.1659 g/kg,?-polylysine 0.0411g/kg and nisin 0.0659 g/kg.The total number of colonies was found to be effectively controlled by inoculating the egg curds with preservatives and incubating them at 37?for48 h.The total number of egg curd colonies measured was 2.7×10~3 CFU/g,while the total number of egg curd colonies without preservative was 2.9×10~5 CFU/g,a reduction of99.07%.In addition,by sampling the environment,tools,raw materials,etc.in the production process,it can be determined that Bacillus sp.LAMI 002 is derived from brine made from egg curds.