factors affecting microbial growth pdf

Intrinsic and extrinsic factors play very important roles to maintain a microbiologically safe food system. $.' Hydrogen ion concentration (pH) 2.4. Nutrients needed by microorganisms include: Carbon carbon containing compounds are needed as an energy source (ex. Effect of oxygen availability 7. factors that affect organisms because they are in excess (e.g.,. Biological structure 2.6. <> Warmth, moisture, pH levels and oxygen levels are the four big physical and chemical factors affecting microbial growth. Hydrogen ion concentration (pH) • Most bacteria grow best at neutral or weakly alkaline pH usually between 6.8 and 7.5. %�� Microbial membrane are disrupted by temperature extremes. Those factors inherent to the food are intrinsic factors. Bacteria by virtue of mechanical strength of their cell wall are able to … �� JFIF ` ` �� C 1. Adopting good housekeeping practices to reduce microbial growth . Foods such as … Intrinsic and extrinsic factors that affect growth of microorganism and help us understand how to preserve food Oxygen requirement. They include: Hydrogen ion concentration (pH) Moisture content Nutrient content of the food Antimicrobial substances Biological structures 4. 3 0 obj Describe the enzymes observed in … *�,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�� Metabolic processes Primary metabolism of an organic compound has been deﬁned as the use of the substrate as a source of carbon and energy. 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. These include natural food compounds, preservatives, the oxidation-reduction potential, aw, and pH. 1). 3. <> <> of 5.5-8.0. 3 0 obj Extrinsic factors are those that refer to the environment surrounding the food such as temperature. 6 0 obj endobj �Q�r��/��^ܕ�*��~~�#��:�j!Y#��/��7E��N3- The factors are: 1. Factors affecting growth of Micro-organism in food (Intrinsic and Extrinsic) ... influence redox potential of food and finally the microbial growth. Microbial growth, and, in some cases, the production of microbial metabolites, may be particularly sensitive to alterations in aw. Effect of nutrient availability 6. Meats have abundant protein, lipids, minerals, and vitamins. 4 0 obj endobj L�FP��W��J��#��9{H�� V��C��5��)>�3-_T��M�jo�H�z�'�eqjN�}��;�+gE�znZģ�! endobj Pathogens vary in their ability to produce disease. <> �5k��"�MiSV��Pm�*i��=�u��o� %�� endobj %PDF-1.5 Antimicrobial components. Compounds affecting microbial enzymes (oxidative agents, chelating agents, heavy metals, antimetabolites) Compounds reacting with DNA ( chemical mutagenes – alkylating or deaminating agents, cytostatics) The factors affecting microbial survival and growth in foods determine the nature of spoilage and any health risks. 2. ",#(7),01444'9=82. High temperatures damage microbes by denaturing enzymes, transport carriers, and other proteins. Nutrient content 2.5. It is notable that each microbial species possesses a definitive pH growth range and a distinctive pH growth optimum (Fig. Microbial cells obtain all required nutrients from food nearby. Plant foods have high concentrations of different types of carbohydrates and varying levels of proteins, minerals, and vitamins. Microorganisms generally have optimum and minimum levels of aw for growth depending on other growth factors in their environments. glucose) for building blocks. Effect of water availability 9. Factors Affecting Microbial Growth Food. 1 0 obj Dampness is a big player in the growth of fungi. affect microbial growth in foods can be. 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 INTRODUCTION Microbial growth is defined as increase in number of cells, not the size of the cells. PH 4. Chapter 6: Microbial Growth Microbial Growth: 4Refers to an increase in cell number, not in cell size. Osmotic pressure (salt tolerance). View food spoilage.pdf from PUPLIC HEA HSC 1104 at University of Guyana. 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. Use the terms that describe a microbe’s growth range or requirement for each of the factors that influence microbial growth 2. Factors affecting bacterial growth are: 1. depending on a number of factors. Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. Main factors affecting microbial growth 5. 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/ Summarize the adaptations of extremophiles to their natural habitats 3. Influence. At very low temperatures membranes also solidify and enzymes also do not function properly. toxic compounds). Mohamed Saad Abo-Elenain. Temperature requirement. f. Growth factors. Hence factors such as osmotic pressure and salt concentration of the solution affect the growth of bacteria. <>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.2 841.92] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> endobj Effect of temperature 8. Factors Affecting. Factors affecting microbial growth 1. The kinetics of microbial growth are covered in the third part of the chapter. This substrate serves as an electron donor resulting in microbial growth. 4Bacteria grow and divide by binaryfission, a rapid and relatively simple process. Just like … FOOD SPOILAGE AND FOOD PRESERVATION Intrinsic Factors Affecting Microbial Growth • pH • Moisture Content • Water Factors affecting microbial growth 2.1 Moisture content 2.2. 5 0 obj : {ѧ�"�_|��X��#E��z�M��Sܐ�;z��p��E�T 2 0 obj Temperature is the most important factor that determines the rate of growth, multiplication, survival, and death of all living organisms. Factors affecting bacterial pathogenicity. 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 7 0 obj <>>> Most fresh foods, such as fresh meat, vegetables, and fruits, have a. w values that are close to the optimum growth level of most. x��VKk�@��z�Z�h��`h��Ѓ�ډK�4��@}gVJ*�)�꥘(b5�of��0M�� Other factors that control microbial populations are moisture content, dissolved oxygen, and temperature. 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. Temperature 3. pH 4. Abstract : When microorganisms grow in food, they cause varying degrees of change in the food's characteristics as a result of metabolic activity. The following points highlight the six main physical factors affecting the growth of microorganisms. <>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 540 720] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Microbial Growth FATTOM Food Acid Temperature Time Oxygen Moisture Factors Affecting Microbial Growth. Factors affecting the microbial growth in food 7 th European Food Safety & Standards Conference November 13-14, 2017 | Athens, Greece. Nitrogen needed for amino acids and nucleotides; some can synthesize … availability to facilitate growth of microorganisms. Are factors external to the food that affect microbial growth. endobj Oxidation-reduction potential 2.3. Microbes obtain almost all their nutrients in solution from surrounding water. 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. All four phases of the microbial growth curve are important to Factors affecting microbial growth in food (a)Intrinsic factors: These are inherent in the food. Growth factors are organic compounds such as amino acids , purines , pyrimidines , and vitamins that a cell must have for growth but cannot synthesize itself. stream 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. 4 0 obj endstream Summarize the strategies used by nonextremophiles to acclimate to changes in their environment 4. Some microorganism can hydrolyze triglycerides and other types of fats by microbial lipase and produces glycerol and smaller fatty acid. %PDF-1.5 stream to inhibit microbial growth is called hurdle technology. stream <>>> Some of the important factors affecting bacterial growth are: Nutrition concentration In most buildings, warmth and moisture are the biggest overall issues present. • 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) Pathogenicity is the ability of a microorganism to cause disease in another organism, namely the host. Requirements for Growth Physical Requirements 1.Temperature: Microbes are loosely classified into several groups based on their preferred temperature ranges. <> 2.4. N��q��r�dˎ�o��\�o�X�K��-�y��[��9�g��C@2�?�;|tT��k��ӱ��$��[*��&zKH��ӒV�0_�OKZôqE�6!��%c��. •The requirements for microbial growth can be divided into two main categories: physical and nutritional. <> Organisms having complex nutritional requirements and needing many growth factors are said to be fastidious . . Microbial Growth. 1 0 obj Microbial growth in foods is very complex and diversified, which is governed by biochemical, environmental, and genetic factors along with their nutritional class. 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. Most muscle foods have low levels of carbohydrates. 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. Hurdle technology is becoming an increasingly popular preservation strategy. Posters & Accepted Abstracts: J Food Microbiol Saf Hyg. endobj endobj Food. One indicator of microbial response is their taxonomic classification. 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. endobj 7.3 Influences of environmental factors on growth 1. ability to participate in chemical/biochemical reactions, and its. Solutes and Water Acidity 2. It may a1so be extended to inc1ude bio1ogica1 factors. 2 0 obj Factors that. <> '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� ��$MH�)p�� o�D�5=��)��ī�1"�+]2��CU0�$�`��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 1) Oxygen requirement: A microbe that is capable of causing disease is referred to as a pathogen. The use of multiple environmental factors (i.e., pH, salt concentration, tem-perature, etc.) Pepsico, Egypt . The specific information about growth characteristics of microorganism can be given by a number of factors affecting microbial growth. Introduction Intrinsic and extrinsic factors are both important to microbial growth. A number of factors affecting microbial growth: 4Refers to an increase number. 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