outline factors that may influence microbial growth in foods

Sofos, in Encyclopedia of Food Safety, 2014. Hence, bacterial growth occurs. 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. For most microbes, growth in indicated by an increase in cell # because cell division accompanies growth C. Batch culture = cultivation of organisms in 1 batch of liquid medium D. Growth curve (Fig. Energy Sources Organisms harvest energy either from sunlight or chemical compounds Phototrophs: obtain energy from sunlight photo means "light" Includes: plants, algae, and photosynthesis bacteria Chemotrophs: extract energy from chemical compounds chemo means "chemical" This was mostly done by lowering the water activity of foods. More acidic foods can typically be stored longer without spoiling. Some of these changes, like those taking place during fermentation, are desirable, while others, like those resulting in food spoilage and food poisoning, are undesirable. Factors such as oxygen, pH, temperature, and light influence microbial growth. milk, meat, they do not show pH reduction. Intrinsic factors are those that are characteristic of the food itself; extrinsic factors are those that refer to the environment surrounding the food. Factors Affecting Microbial Growth Esha tur razia . Therefore, it’s important to have an understanding of the conditions that aid microbial growth. which of the following are environmental factors that affect microbial growth pH, nutrients, temperature, osmotic pressure, atmospheric gases the slowed growth or lack of growth of an organism at temperatures of pH outside of its ideal range is most likely due to changes in its Learn vocabulary, terms, and more with flashcards, games, and other study tools. and brings some undesirable changes which make the food inedible to eat. -- Created using Powtoon -- Free sign up at http://www.powtoon.com/youtube/ -- Create animated videos and animated presentations for free. Intrinsic factors are those that are characteristic of the food itself; extrinsic factors are those that refer to the environment surrounding the food. Each species has an optimum and a range of pH for growth. In the case of questionable products, further scientific evidence--such as modeling of microbial growth or death, or actual microbiological challenge studies--may help to inform the decision. The optimum growth pH is the most favorable pH for the growth of an organism. Microbial growth is greatly affected by chemical and physical ... (i.e. Growth rate is greater when all conditions are optimized and any alteration on these conditions will reflect on the growth rate (figure 2). LECTURE 3 INTRINSIC AND EXTRINSIC FACTORS AFFECTING THE TYPE AND NUMBER OF MICROORGANISMS IN FOODS 2. Growth of bacteria is affected by many factors such as nutrition concentration and other environmental factors. Any change in the environmental pH may either enhance the enzyme activity or inhibit the activity (Table 19.2). Water activity is defined as the ratio of water vapor pressure of the food substrate to the vapor pressure of pure water at the same temperature (Jay 2000b, p 41): For questions about accessibility and/or if you need additional accommodations for a specific document, please send an email to ANR Communications & Marketing at anrcommunications@anr.msu.edu. Science Advisory Board. Temperature is the most important factor that governs microbial growth in food. Therefore bacteria is unlikely to grow in dried flours, spices and dehydrated fruits but molds may grow. FACTORS THAT INFLUENCE MICROBIAL GROWTH IN FOOD FACTORS THAT INFLUENCE MICROBIAL GROWTH IN FOOD Characteristics of the food itself is called intrinsic factors (substrate limitation) Factors that are external to the food is called extrinsic factors (environmental factors) Implicit factors Processing factors Chapter 6 Lecture Notes: Microbial Growth I. 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