Expert system for prediction of microbial growth, survival or death for the safety of food and agricultural product

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The purpose of this research is to develop a expert system for the prediction of microorganism growth survival or death. To make the system, following researches were performed.1)Data collection of microbial growth and death : The growth curves of B.cereus and S.epidermidis were obtained under various conditions of temperature, pH and NaC1 concentration as well as the survival curves of P.digitatum, P.italicum.2)Data collection of physical properties of food and agricultural products : The dielectric properties of soy sauce were analyzed theoretically with Cole-Cole relation and including the effect of ionic conductivity. The important parameters such as relaxation wavelength, static component of the dielectric constant and ionic conductivity, were determined and tabulated for various conditions.3)Research on the temperature history of fresh produce : To predict the growth of microorganisms the temperature of fresh produce was measured during distribution from harvesting to a wholesale … More market.4)Development of mi crobial growth model : A modified Gompertz model was developed for the prediction of microbial growth. Parameters of the model were obtained and each parameter was expressed as polynomial equation. In addition, the model was expressed using a lag phase TL, maximum growth rate Rc and Maximum population of microorganisms Nmax. TL and RG were dependent on the temperature so that these parameters were built into the model equation as the function of the temperature. The predicted values of B.cereus and S.epidemidis growth were agreed well with experimental values at the changing temperature of fresh produce described above 3). A radiation heat transfer models with the combination of the Monte Carlo method and two-dimensional heat transfer model based on the fundamental quantum physics of radiation and fluid dynamics were developed. Monte Carlo far infrared radiation simulations were performed in CFD code ANSYS CFX5.7 to investigate the suitability of the method for surface contamination. Less