factors that affect organisms because they are in excess (e.g.,. Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. Just like … View food spoilage.pdf from PUPLIC HEA HSC 1104 at University of Guyana. depending on a number of factors. Temperature 3. pH 4. Mohamed Saad Abo-Elenain. <>>> Microbes obtain almost all their nutrients in solution from surrounding water. One might ask how these organisms survive in such conditions given that extreme pH levels denature proteins, which in turn would dramatically affect cellular metabolism and eventually viability. Factors affecting bacterial pathogenicity. Antimicrobial components. Oxidation-reduction potential 2.3. $.' Solutes and Water Acidity 2. Food. Microorganisms generally have optimum and minimum levels of aw for growth depending on other growth factors in their environments. Factors affecting Microbial growth Physical factors •pH •Temperature •Osmotic pressure •Hydrostatic pressure •Moisture •Radiation •Oxygen concentration Nutritional factors •Carbon •Nitrogen •Sulfur •Phosphorus •Trace elements •vitamins endobj At very low temperatures membranes also solidify and enzymes also do not function properly. Factors Affecting Microbial Growth Food. Pathogens vary in their ability to produce disease. 4 0 obj • Growth factors are organic compounds that are essential cellular components or precursors of these components but cannot be synthesized by the organism • Major Classes of Growth factors 1. amino acids 2. purine and pyrimidines 3. vitamins (e.g., thiamine, biotin, cobalamin, pyridoxine) Intrinsic factors include those that are internal to the food product itself, such as nutrient content, pH levels, water activity, redox potential, and other antimicrobial components acting as defense mechanisms against microbes. Compounds affecting microbial enzymes (oxidative agents, chelating agents, heavy metals, antimetabolites) Compounds reacting with DNA ( chemical mutagenes – alkylating or deaminating agents, cytostatics) <> Bacteria by virtue of mechanical strength of their cell wall are able to … <> The factors affecting microbial survival and growth in foods determine the nature of spoilage and any health risks. Hence factors such as osmotic pressure and salt concentration of the solution affect the growth of bacteria. of 5.5-8.0. ���� JFIF ` ` �� C %PDF-1.5 Factors affecting growth of Micro-organism in food (Intrinsic and Extrinsic) ... influence redox potential of food and finally the microbial growth. 2.4. 3. Intrinsic and extrinsic factors play very important roles to maintain a microbiologically safe food system. Biological structure 2.6. 7 0 obj All four phases of the microbial growth curve are important to 1 0 obj Chapter 6: Microbial Growth Microbial Growth: 4Refers to an increase in cell number, not in cell size. N��q��r�dˎ�o��\�o�X�K���-�y����[������9�g��C@2�?�;|tT�����k�������ӱ���$���[*��&zKH��ӒV�0_�OKZôqE�6!��%c���. Pathogenicity is the ability of a microorganism to cause disease in another organism, namely the host. The kinetics of microbial growth are covered in the third part of the chapter. Summarize the adaptations of extremophiles to their natural habitats 3. Adopting good housekeeping practices to reduce microbial growth . f. Growth factors. endobj The use of multiple environmental factors (i.e., pH, salt concentration, tem-perature, etc.) PH 4. x��Z�o�8��A��m͈�DJŢ�����aY`s����iz���ٶ���?L�&%u���-����7]\�Z|���/o~���.~���z���o�W�������.������/*�5g/t#/�6�gU�_�v~�~�T�~U6��^�e�x*�[�/r����Pn�z�\6�⺔vP�)��R/ glucose) for building blocks. �5k��"�MiSV��Pm�*i����=�u��o� Meats have abundant protein, lipids, minerals, and vitamins. INTRODUCTION Microbial growth is defined as increase in number of cells, not the size of the cells. 5 0 obj Organisms having complex nutritional requirements and needing many growth factors are said to be fastidious . <>>> 1. endobj These include natural food compounds, preservatives, the oxidation-reduction potential, aw, and pH. Factors affecting microbial growth 2.1 Moisture content 2.2. Microbial Growth. 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