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