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Unformatted text preview: FST 3202 FOOD MICROBIOLOGY EXPERIMENT 1 & 2 Enumeration, Isolation and Identification of Spoilage Bacteria in Food- Mea t NAME : LIEW KAI WEN 130815 STEPHANIE CHEW 129764 LIM LI YUIN 129782 DATE : 11/07/2006 PROGRAM : BSTM LECTURER : PROF DR. SON RADU DR FARINAZLEEN MOHD GHAZALI SEMESTER 3, SESSION 2006/2007 Title: Enumeration, Isolation and Identification of Spoilage Bacteria in Food- Meat Objectives: 1. To master the technique to prepare the media. 2. To observe the microbial activity on the meat surface by cultivating them in the suitable media. 3. To carry out Gram staining for differentiating between two principal groups of microorganisms: Gram-positive and Gram-negative. 4. To identify, differentiate and classify microorganisms found in meat based on the interpretation of their biochemical activities. 5. To master the technique to prepare the biochemical test. 6. Explain the relevance of each biochemical test. Introduction : Microorganisms are ubiquitous. They are found in soil, air, water, food, sewage, and on body surfaces. In short, every area of our environment is replete with them. As do all other living organisms, microorganisms require certain basic nutrients and physical factors for the substance of life. However, their particular requirements vary greatly. Understanding these needs is necessary for successful cultivation of microorganisms in the laboratory. Media generally contain a source of carbon, nitrogen and vitamins. Glucose (dextrose) is the most widely utilizable carbon source, so it is commonly used in growth media. Sucrose may be used in some media. Nitrogen sources include peptone, yeast extract, malt extract, amino acids, ammonium and nitrate compounds. We will use mostly natural media based on materials such as cornmeal, carrots, hay, potatoes, oatmeal, soil, etc. Semi-synthetic media, containing both natural ingredients and defined components include Malt Extract Agar, Malt Agar. We probably will not be using Synthetic or defined media which contain precise amounts of a carbon source, vitamins and minerals. (5) Meat is considered to be spoiled when it is cant be consume anymore. A variety of factors can cause meat to spoil including micro-organisms, exposure to air, and improper freezing techniques. Spoiled meat may be inedible due to unpleasant tastes and odors or may be unsafe for consumption especially when micro-organisms have caused the meat to spoil. The most common cause of meat spoilage is the deterioration of meat caused by micro-organisms (bacteria, yeasts, and molds). Hugh-Leifson carbohydrate utilization or Oxidation- fermentation test is a bioxidation test used to decide the oxidative or fermentative metabolism of a carbohydrate or its non-utilization. This was developed by Hugh and Leifson who described the taxonomic significance of fermentative versus oxidative metabolism of carbohydrates by gram-negative bacteria. Oxidative organisms will showed little or no growth by producing acid reaction in the open tubes but there is definitely no acid...
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This note was uploaded on 04/27/2010 for the course BSTM 3202 taught by Professor Fari during the Spring '10 term at Zhejiang University.
- Spring '10