Research On Bacterial Proliferation And Detection In Raw Milk

Both milk and dairy products are rich in nutrition, among the best nutrition food for human beings and the best medium for the growth of microorganisms. Therefore, it is necessary to analyze the proliferation of bacteria in milk and to study a rapid and effective method for detecting the amount of bacteria. For these two issues, the mathematical models of bacterial proliferation and bacterial detection in milk are established, through the mechanism analysis and data and with the mathematical software of MATLAB. Three parts of main work are as follows:Firstly, based on the premise of assumption that the bacteria in raw milk are a single species, for storage temperature and time, two main factors that affect the proliferation of bacteria in raw milk, two mathematical models of bacterial proliferation are established, one applied to a short period and the other applied to a long period. The proliferation laws of bacteria are fitted by the existing data. The fitting images embody intuitively that the short-term model can describe well the bacterial proliferation for the short period. Meanwhile, the amount of bacteria in milk could be known quickly by the expression of the solution of the model. Through the analysis of the application of the result of the model, it's known that the impact of temperature is significant on bacterial proliferation.Secondly, by analyzing the microbial changes at room temperature in raw milk, the proliferation of Streptococcus and Lactobacillus are chosen to study. Through the mechanism analysis of the interaction of these two species, a mathematical model of the interaction among these two species and their nutrition-Lactose is established. First, the stability of the equilibrium point is obtained by the qualitative analysis, and then under the same initial value the numerical simulations of the model are given by two different parameters. By the analysis of simulation results, it is concluded that the model can describe well the proliferation of these two species and at the same time it is shown that it is an effective way to store raw milk at a low temperature, which can ensure the quality of raw milk.Finally, through the mechanism analysis of the change of color, a mathematical model showing the change of color difference with time is established, and the fitting to data by model is given. Through the model analysis and the quantitative analysis of color changes, based on the color difference method, the mathematical model of detecting the total amount of bacteria in raw milk is established. Compared with other detection models, the practicality and advantages of the model are obtained. Besides, the scan time is only 10 minutes with this model, which well shows the idea of rapid detection.