PPT-The major factors which effect on microbial growth in foods include

1 Temperature 2 PH 3 Water activity 4 Oxygen and redox Temperature Minimum Temperature The temperature below which no growth occurs At temperature below the minimum the properties of cell membranes change so that they can no longer transport materials into the cell. Dr. . Kamal. E. M. . Elkahlout. Food Microbiology 2 . Microbial Nutrition and Factors Affecting Growth. Intrinsic and Extrinsic Factors . Factors affecting the growth and survival of micro-organisms in foods. 1. 41. Copyright © McGraw-Hill Global Education Holdings, LLC. Permission required for reproduction or display.. Microbial Growth and . Food . Spoilage. Results . from growth of microbes in food. alters food visibly and in other ways, rendering it unsuitable for . A. Microbial Reproduction. 1. binary (transverse) fission. A) parent cell enlarges and duplicates all its genetic material. B) DNA copies move to opposite ends of parent and attach to a section of the cell membrane as it begins to pinch together at the center. In the Environment. Table 9.1 Terminology of Microbial Control. Figure 9.1 A plot of microbial death rate.. Basic Principles of Microbial Control. Action of Antimicrobial Agents. Alteration of cell walls and membranes. Microbiology. Microbial Growth. Microbial requirements for growth:. 1. . Physical. A. . Temperature. Optimal growth temperature. Permissible range. human pathogens optimal = . 37°C. Microbial Growth. The ability of microorganisms to grow or multiply in a food is determined by the food environment ( intrinsic environment of food) as well as the environment in which the food is stored (extrinsic environment ).. (a) Intrinsic factors: . These. . are inherent in the food. They include:. pH,. . water activity,. . oxidation reduction potential,. . nutrient content,. . antimicrobial contents,. . biological structure. Musafer. PhD. Microbial growth defined as an increase in cellular constituents resulting an increase in a microorganism size, population number or both.. 1-Lag phase. When M.O are inoculated into fresh culture medium, will not reproduce immediately, therefore this period is called the lag phase. . Growth: . A. n . increase in cell number, not in cell size. .. Bacteria . grow and divide by binary fission, a rapid and relatively simple process. .. Phases . of Growth Bacterial Growth Curve : . When . Cause of spoilage:. Spoilage may be due to one or more of the following:. 1. Growth and activity of microorganisms. 2. Insects. 3. Action of the enzymes of the plant or animal food.. 4. Purely chemical reactions i.e., those not . biotechnology.important. branch of Microbiology where economically valuable products are produced from cheaper raw materials by using large culture of . m.o.. Up stream and Downstream process.. Screening-Definition.. 9. Figure 9.1 A plot of microbial death rate.. Constant percentage. of the extant population. is killed each minute. Basic Principles of Microbial Control. Action of Antimicrobial Agents. Alteration of cell walls and membranes. Microbiology. Outline. Microbial growth . in . natural environments. . Measurement . of . microbial population size. Principles of . microbial control. . Physical, chemical and biological control. . Kinetics. Growth Curve. Log CFU/ml. Optical Density. Lag. First Order Kinetics. Food microbiology is concerned with all phases. Of microbial growth (. lag,log. , stationary, death phase).Growth curves are normally plotted as the number of cells on a log scale or log10 cell number versus time..