Processing factors. Hydrogen Ion Concentration (pH): All the microorganisms have a minimal, maximal and optimal pH for their growth, survival and activity of their ... 2. The same exponential growth rule applies to filamentous fungi which grow by hyphal extension and branching since the rate of branching normally increases with hyphal length. Bacteria and fungi are the most common group of microbes that are implicated in food spoilage; and these spoilage organisms make use of nutritive factors or … Like so, the type of nutrient content, pH, water activity, and oxygen are intrinsic factors that generally have greater influence on microbial growth in foods. In fact, the microorganisms … In the course of growth, harvesting/slaughter, processing and storage, food is subject to contamination from a range of sources. In All Topics, Food Science 0 Comments. A continual challenge that we have in the food industry is keeping microbial contamination and growth under control. The real danger stems from certain bacteria called pathogens, which are the ones that cause food poisoning. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. If, however, we perform the experiment measuring microbial numbers with time and then plot log x against time, we obtain the curve shown as Figure 3.1 in which exponential growth occurs for only a part of the time. ___ factors which affect microbial growth & survival in foods relate to the makeup of the specific bacterium itself. Some of the important factors affecting bacterial growth are: Nutrition concentration. Each type of food has its own characteristic constituents which may affect the growth of microbial cells. Such factors are summarised in Table 1. 6.1.1. or, taking natural logarithms and re-arranging: where xo is the biomass present when t = 0. Microbe-microbe interactions. Stress responses. A simple analysis of this curve can distinguish three major phases. • It reflects the dependence of microbial growth on rate-limiting enzyme reaction. If you continue browsing the site, you agree to the use of cookies on this website. Aw is the ratio of the vapor pressure of water in the product to the vapor pressure of pure water at a certain temperature. Redox Potential (Eh): 4. water activity. Factors affecting microbial growth in Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. Each chapter explores the scientific principles of the specific environmental factor; methods of measurement; and effects on growth and … Factors affecting microbial growth in food Processing factors • Processing factors: • Slicing • Washing • Packing • Irradiation • Pasteurization 43. humidity. The Population Growth Curve of Cell (Explained With Graph), Heat Sensitivity of Micro-Organisms | Microbiology. Privacy Policy3. Microbial growth is considered insignificant for practical purposes when Aw is lower than 0.7. We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. Intrinsic or food related parameters are inherent to the food product; they are the chemical and physical characteristics of food. Molds and yeasts can affect a wide range of products which have low pH or water activity (aw). Temperature of storage. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments, The best answers are voted up and rise to the top. Implicit. This allows food to … Name the types of nitrogenous bases present in the RNA. Why mitochondria is called as the power house of the cell? Intrinsic or food related parameters are those parameters of plants and animal tissues which are inherent part of the tissue. A variety of intrinsic and extrinsic factors determine whether microbial growth will preserve or spoil foods, as shown in Table 3.3. Before sharing your knowledge on this site, please read the following pages: 1. These are: • Temperature of storage • Relative humidity of the environment • Presence and concentration of gases • Presence and activities of other microorganisms. Water Activity or Moisture Content (aw): 3. A single bacterium with a doubling time of 20 minutes (µ= 2.1 hr-1) growing in a food, or pockets of food trapped in equipment, can produce a population of greater than 107 cells in the course of an 8-hour working day. This last group of factors (subsumed under intrinsic properties by Mossel and Ingram) usually exert their effect in one of two ways: either they change an intrinsic or extrinsic property, for example slicing a product will damage antimicrobial structures and increase nutrient availability and redox potential, or they eliminate a proportion of the product microflora as would occur in washing, pasteurization or irradiation. For convenience they can be divided into four groups along the lines suggested 40 years ago in a seminal review by Mossel and Ingram (Table 3.1) physicochemical properties of the food itself (intrinsic factors); conditions of the storage environment (extrinsic factors); properties and interactions of the micro­organisms present (implicit factors); and processing factors. Intrinsic Parameters in Food: 1. and so influence growth-Eg. Finally, changes in the medium as a result of exponential growth bring this phase to an end as key nutrients become depleted, or inhibitory metabolites accumulate, and the culture moves into the stationary phase. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy. Implicit factors are the result of mutual interactions in mixed microbial populations. The word “factor” is extremely broad, and it means that practically anything can be an implicit factor. The significance of exponential growth for food processing hardly needs emphasizing. Minor fluctuations in these factors, either individual or multiple, can alter the stability of a food product and make them susceptible to the growth of spoilage or pathogenic microorganisms. When microorganisms grow in food they cause varying degrees of change in the food's characteristics as a result of metabolic activity. Temperature: All forms of life are greatly influenced by temperature. Accordingly, the slope of this portion of the curve will equal the organism’s specific growth rate µ, which itself will depend on a variety of factors (see below). 1. 3 main temp groups of microbes (implicit factors of the microbes) Thermophiles: high temp - optimal 55 degrees (range 45-70) 1. These organisms don't produce any smell, discoloration, or any other changes you can detect with your senses. No public clipboards found for this slide. Disclaimer Copyright, Share Your Knowledge Looks like you’ve clipped this slide to already. 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