factors affecting microbial growth pdf

Influence. Dampness is a big player in the growth of fungi. As our foods are of plant and animal origin, it is worthwhile to consider those characteristics of plant and animal tissues that affect the growth of microorganisms. View food spoilage.pdf from PUPLIC HEA HSC 1104 at University of Guyana. All four phases of the microbial growth curve are important to *�,N:��_FجiWIʃ�sY.��,2j3��Q��c,d�/��>oFyQ��9��W��?��:k턺��BJꪀ�u=��M&m��oE]��>�1�ki@a��bj�)7�%/Y+/x�_�� .�@�57f��p�p��r��V� ��:k��` �mlw�m��PQ��]�*!/t�ji�qq��T�:�:c�hΕ�V��a*��O8>'Ԛ��(6��8��sew��x��V��/F�^��;��j��AyO-�z��}W�̸��{�8o�yٿQ�:��Uпw�� glucose) for building blocks. Some microorganism can hydrolyze triglycerides and other types of fats by microbial lipase and produces glycerol and smaller fatty acid. stream Microbial Growth FATTOM Food Acid Temperature Time Oxygen Moisture Factors Affecting Microbial Growth. endobj Microbes obtain almost all their nutrients in solution from surrounding water. ",#(7),01444'9=82. . Microbial growth, and, in some cases, the production of microbial metabolites, may be particularly sensitive to alterations in aw. Microorganisms generally have optimum and minimum levels of aw for growth depending on other growth factors in their environments. Antimicrobial components. Abstract : When microorganisms grow in food, they cause varying degrees of change in the food's characteristics as a result of metabolic activity. The kinetics of microbial growth are covered in the third part of the chapter. 6 0 obj L�FP��W��J��#��9{H�� V��C��5��)>�3-_T��M�jo�H�z�'�eqjN�}��;�+gE�znZģ�! Chapter 6: Microbial Growth Microbial Growth: 4Refers to an increase in cell number, not in cell size. <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 540 720] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> In most buildings, warmth and moisture are the biggest overall issues present. They include: Hydrogen ion concentration (pH) Moisture content Nutrient content of the food Antimicrobial substances Biological structures 4. Adopting good housekeeping practices to reduce microbial growth . Solutes and Water Acidity 2. Just like … Effect of nutrient availability 6. endobj •The requirements for microbial growth can be divided into two main categories: physical and nutritional. Intrinsic and extrinsic factors play very important roles to maintain a microbiologically safe food system. : {ѧ�"�_|��X��#E��z�M��Sܐ�;z��p��E�T Most fresh foods, such as fresh meat, vegetables, and fruits, have a. w values that are close to the optimum growth level of most. Main factors affecting microbial growth 5. Hydrogen ion concentration (pH) • Most bacteria grow best at neutral or weakly alkaline pH usually between 6.8 and 7.5. Factors affecting microbial growth 1. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Biological structure 2.6. High temperatures damage microbes by denaturing enzymes, transport carriers, and other proteins. 1 0 obj f. Growth factors. Compounds affecting microbial enzymes (oxidative agents, chelating agents, heavy metals, antimetabolites) Compounds reacting with DNA ( chemical mutagenes – alkylating or deaminating agents, cytostatics) Nitrogen needed for amino acids and nucleotides; some can synthesize … Factors Affecting Microbial Growth Food. endobj Summarize the strategies used by nonextremophiles to acclimate to changes in their environment 4. xۣ�H�V�ҐE�Ҍ&��5~"r"@ʃB��=�ABZa��;\[8B�׿�Kx{��j0�m�3QC"�LtH�1�F�V��8�o�y�@:Ū��iـ��Gˎ$��]~A�~Eh�N*F�?��b�;|x&`ye�l"��¡�^͜3ݤ%�˞F�M��7�}@Gy�� Xӄ�`虄̑|:��'d��f�EE9dH�=X7 Ȑ_>"WӐ<0,�xRW��_�eY�\�ɘ5��)(��:�m toxic compounds). <> 2 0 obj INTRODUCTION Microbial growth is defined as increase in number of cells, not the size of the cells. Temperature requirement. Pathogens vary in their ability to produce disease. Factors affecting Microbial growth Physical factors •pH •Temperature •Osmotic pressure •Hydrostatic pressure •Moisture •Radiation •Oxygen concentration Nutritional factors •Carbon •Nitrogen •Sulfur •Phosphorus •Trace elements •vitamins 3 0 obj to inhibit microbial growth is called hurdle technology. 'a1��E�� #�fmo��ʆ��Y@��0��V/>,��C��±��"�Voݒ"��4#N��A�I;1KE�ʣ|Ӝ@�m��ԑh�p�%�_\�2��4��XZ�~O�T(&�t �k&�P�)5�3��졌�0�G��S=�X�X� N��q��r�dˎ�o��\�o�X�K��-�y��[��9�g��C@2�?�;|tT��k��ӱ��$��[*��&zKH��ӒV�0_�OKZôqE�6!��%c��. Organisms having complex nutritional requirements and needing many growth factors are said to be fastidious . %�� 1 0 obj Meats have abundant protein, lipids, minerals, and vitamins. Effect of water availability 9. �Q�r��/��^ܕ�*��~~�#��:�j!Y#��/��7E��N3- <> of 5.5-8.0. A microbe that is capable of causing disease is referred to as a pathogen. 5 0 obj Pathogenicity is the ability of a microorganism to cause disease in another organism, namely the host. Hydrogen ion concentration (pH) 2.4. endobj stream Pepsico, Egypt . Factors affecting bacterial pathogenicity. 4Bacteria grow and divide by binaryfission, a rapid and relatively simple process. 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/ 2. endobj Temperature is the most important factor that determines the rate of growth, multiplication, survival, and death of all living organisms. Microbial growth in foods is very complex and diversified, which is governed by biochemical, environmental, and genetic factors along with their nutritional class. <> 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. Metabolic processes Primary metabolism of an organic compound has been deﬁned as the use of the substrate as a source of carbon and energy. 1. Foods such as … stream At very low temperatures membranes also solidify and enzymes also do not function properly. 3. endobj endobj endobj Oxidation-reduction potential 2.3. Effect of temperature 8. Nutrient content 2.5. %PDF-1.5 Introduction Intrinsic and extrinsic factors are both important to microbial growth. endobj Bacteria by virtue of mechanical strength of their cell wall are able to … These include natural food compounds, preservatives, the oxidation-reduction potential, aw, and pH. Mohamed Saad Abo-Elenain. Are factors external to the food that affect microbial growth. Posters & Accepted Abstracts: J Food Microbiol Saf Hyg. <> 1) Oxygen requirement: Microbial membrane are disrupted by temperature extremes. The specific information about growth characteristics of microorganism can be given by a number of factors affecting microbial growth. Nutrients needed by microorganisms include: Carbon carbon containing compounds are needed as an energy source (ex. availability to facilitate growth of microorganisms. Factors affecting the microbial growth in food 7 th European Food Safety & Standards Conference November 13-14, 2017 | Athens, Greece. factors that affect organisms because they are in excess (e.g.,. %PDF-1.5 3 0 obj 4 0 obj Describe the enzymes observed in … <> • 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) 2.4. Factors that. Summarize the adaptations of extremophiles to their natural habitats 3. 7.3 Influences of environmental factors on growth 1. <> The major groups have been categorized in food-spoiling, intoxicating, and disease-causing bacteria with their specificity at various temperature, pH, air, O 2 requirement along with the antimicrobial compounds present in the food. Requirements for Growth Physical Requirements 1.Temperature: Microbes are loosely classified into several groups based on their preferred temperature ranges. 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. Factors can be divided into four groups: physicochemical properties of the food, conditions of the storage environment, interactions of microorganisms, and process factors such as physical treatments and addition of chemicals. Factors affecting microbial growth in food (a)Intrinsic factors: These are inherent in the food. The following points highlight the six main physical factors affecting the growth of microorganisms. Most muscle foods have low levels of carbohydrates. �� JFIF ` ` �� C Factors Affecting. Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. 7 0 obj Warmth, moisture, pH levels and oxygen levels are the four big physical and chemical factors affecting microbial growth. Hence factors such as osmotic pressure and salt concentration of the solution affect the growth of bacteria. Growth factors are organic compounds such as amino acids , purines , pyrimidines , and vitamins that a cell must have for growth but cannot synthesize itself. <>>> affect microbial growth in foods can be. Osmotic pressure (salt tolerance). Oxygen requirement. $.' Some of the important factors affecting bacterial growth are: Nutrition concentration ability to participate in chemical/biochemical reactions, and its. 2 0 obj Temperature 3. pH 4. depending on a number of factors. Food. Effect of oxygen availability 7. It is notable that each microbial species possesses a definitive pH growth range and a distinctive pH growth optimum (Fig. 1). FOOD SPOILAGE AND FOOD PRESERVATION Intrinsic Factors Affecting Microbial Growth • pH • Moisture Content • Water <>>> Microbial cells obtain all required nutrients from food nearby. Other factors that control microbial populations are moisture content, dissolved oxygen, and temperature. The factors are: 1. %�� Plant foods have high concentrations of different types of carbohydrates and varying levels of proteins, minerals, and vitamins. Hurdle technology is becoming an increasingly popular preservation strategy. Those factors inherent to the food are intrinsic factors. Factors affecting bacterial growth are: 1. Factors affecting growth of Micro-organism in food (Intrinsic and Extrinsic) ... influence redox potential of food and finally the microbial growth. Factors affecting microbial growth 2.1 Moisture content 2.2. 4 0 obj �5k��"�MiSV��Pm�*i��=�u��o� Intrinsic and extrinsic factors that affect growth of microorganism and help us understand how to preserve food Extrinsic factors are those that refer to the environment surrounding the food such as temperature. endstream Use the terms that describe a microbe’s growth range or requirement for each of the factors that influence microbial growth 2. echocardiography textbook pdf AIntrinsic factors: These are inherent in.Factors Affecting Bacterial Growth- Microbiology Test 3. produce exotoxin that causes botulisim- form of food-poisoning. Microbial Growth. It may a1so be extended to inc1ude bio1ogica1 factors. ��$MH�)p�� o�D�5=��)��ī�1"�+]2��CU0�$�`��3 �q�|ރ;��Q�(�T)�s��(>�K�Oi��Я�k!��mq=��"8irx�W'5��~��2'M�$e��/"ҥ��V )��A�Ū)�l�/��ٌ+��yO�'n��l0��⎍�g��ju��z Z[aL 4M/mvڬ Request PDF | Intrinsic and Extrinsic Factors Affecting Microbial Growth in Food Systems | The food environment can support or reduce the ability of microorganisms to persist, establish and grow. The factors affecting microbial survival and growth in foods determine the nature of spoilage and any health risks. The plants and animals that serve as food sources have all evolved mechanisms of defense against the invasion and proliferation of microorganisms, and some of these remain in effect in fresh foods. 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