Modelling Of Growth Of Staphylococcus Aureus In Whipping Cream

Food safety become a major issues which is associated with national stability and social development and stability, food-borne illness caused by pathogenic microorganisms is one of the most common cause. How to effectively prevent and control outbreaks of foodborne diseases has been the focus of government and the food industry. This research is based on principles of pathogenic bacteria- combinations of high-risk food, put staphylococcus aureus, whipping cream combination as the research object, studies the growth rule of the pathogenic bacteria in those food, Establishes corresponding growth prediction model.Provides scientific basis for risk evaluation of food-borne pathogens,food safety standards and enterprise reasonable process conditions and the implementation of HACCP.Whipping cream is mainly polluted food by staphylococcus aureus, very susceptible to staphylococcus aureus pollution, when staphylococcus aureus enterotoxin accumulated to a certain amount turn to the threaten to human body health.Staphylococcus aureus prediction model of research focuses on the first and second level at home and abroad, and the research has focused on the milk, and the growth model of microorganisms research to whipping cream is basic blank. In order to fill the blank of the staphylococcus aureus growth behavior change in the whipping cream,provide data support for the risk assessment of staphylococcus aureus. This paper tested the growth characteristics of one plant production type A enterotoxin staphylococcus aureus(ATCC26001) in whipping cream kept by Shanghai research institute of food.Firstly, explores the rule of the growth of staphylococcus aureus at different temperature and point on the growth curve, find out the appropriate experimental time interval, and through the experimental study, collected data, analyzed data, Then using Origin8.0software and DMFit(http://modelling.combase.cc/DMFit.aspx) to fit the growth data of microorganisms,Established primary and secondary prediction model of staphylococcus aureus in whipping cream at different temperature. Established primary and secondaryprediction model of staphylococcus aureus in whipping cream at different p H conditions again, and finally set up prediction model of staphylococcus aureus in whipping cream at different Aw and Nisin concentration.Results are as follows:1) Established primary and secondary model at different temperature. There are many factors which affect the growth of microorganisms, such as p H, Aw and biological antistaling agent, etc., but to staphylococcus aureus in whipping cream,temperature is one of the biggest factors, set up primary model of staphylococcus aureus in whipping cream at different temperature 15±1 ℃, 20±1 ℃, 25±1 ℃,30±1 ℃, and 36±1 ℃.Through Baranyi growth dynamics model of staphylococcus aureus in whipping cream of at the constant temperature 15~36 ℃, set up secondary model of maximum specific growth rate and temperature in storage temperature 15~36 ℃,provides the user with one tool which can accurately predict staphylococcus aureus in whipping cream growth dynamic in the process of circulation and consumption.2) Established Growth model of staphylococcus aureus in whipping cream at different p HFirst class and second class model are established at the condition of different p H.Results show that with the increase of p H, the maximum specific growth rate of staphylococcus aureus firstly increases then decreases, modified Gompertz growth fitting curve is established at different p H, the second model is the modified Arrhenius model fitting the curve of the maximum specific growth rate and p H, the decision of the equation coefficient over 0.9, the fitting is good. The fitting effect of the model validation is good, high accuracy, can be used to predict the growth of staphylococcus aureus in whipping cream at p H range from 5.5~8.0.3) Set up primary growth model of staphylococcus aureus in whipping cream at different water activity and Nisin concentration.By applying the sorbitol to adjust the water activity of cream, adding sorbitol20%±0.1%, 14%±0.1%, 7%±0.1% to 1 L whipping cream respectively, at the same time do blank control; By adding 0.02%, 0.05% Nisin, to 1 L cream do blank control at the same time, monitoring the growth curve at 36 ℃ respectively, using the Linear model and the modified Logistic model growth curve fitting. Established the good effect growth model, finally it is concluded that sorbitol can obviously regulate water activity,which cause the obvious to the growth of staphylococcus aureus, but Nisin has little impact on staphylococcus aureus, can be ignored.