The Effect Of NaCl And Phosphate On Thermal Resistance Of Geobacillus Stearothermophilus

Microbes are the main factors influencing the shelf life of meat product.Thermal sterilization is mainly applied by traditional food industry.With the development of food industry,a series of new sterilization technology were developed by many scholars both at home and abroad,such as microwave sterilization,irradiation sterilization and ultrahigh pressure processing.However,with the advantages of low cost and high safety factor,thermal sterilization is still the most widely used method in meat product enterprises.Most meat products are contaminated in the process by some non-pathogenic bacillus,thermophilic bacteria and high temperature resistant microbial,so these thermophiles and strong heat-resistant spore,such as Geobacillus stearothermophilus and its spore,will still remain in the product,even after thermal sterilization.In order to destroy the thermophiles and spore completely,strong heat treatment is needed theoretically,which may cause the damage of color,quality,structure and nutrition of meat product easily.So pasteurization and heat sterilization under 100? are popular in domestic meat product enterprises.Besides,the effect of thermal sterilization towards bacillus is closely related with heating environment.This study established thermal inactivation models of Geobacillus stearothermophilus ATCC7953 below 100 ? preliminarily,and researched the inactivation regularity of Geobacillus stearothermophilus with different concentration of NaCl,phosphate(sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate)for heat treatment medium,in order to systematically establish the theory system of the effect of mineral salts in meat product on thermal resistance of Geobacillus stearothermophilus,and provide better theoretical basis for the optimization of thermal sterilization conditions in actual meat product process.The results showed that:(1)The inactivation regularity of Geobacillus stearothermophilus ATCC7953 experienced the same at three different center temperatures of 70?,80? and 90?.Before reaching the center temperature,the concentration decreased to a nearly constant value,and the concentration remained nearly constant with the heating time extending to 60 minutes.Besides,the Exponential model were modeled by inactivation curves during thermal processing.(2)With concentration of 2%,4%,6%,8%,10% NaCl solution for heat-treatment medium,70?,80?,90? were set as three center temperatures.Before reaching the center temperature and at the time of 60 minnutes after reaching the center temperature,2% NaCl could improve the heat resistance of Geobacillus stearothermophilus significantly.(3)The concentrations of 1%,2%,3%,4%,5% sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate solution were used as heat-treatment medium.Before reaching the center temperature of 90?,five different concentration of sodium tripolyphosphate and sodium hexametaphosphate could all improve the heat resistance of Geobacillus stearothermophilus significantly.The heat treatment was continued to 60 minnutes after reaching the center temperature of 90?,different concentration of sodium tripolyphosphate and sodium hexametaphosphate all reduced its heat resistance,however,different concentration of sodium pyrophosphate did not have notable effect on the heat resistance of Geobacillus stearothermophilus.