METHODS FOR MICROBIOLOGICAL ASSESSMENTS Specifications require the following to be determined Total Viable Count 30'C 100,000 per gr. max(500,000 for onions) E Coli 10 per gr. max. Coliforms 100 Yeast and mould 1000 per gr. max B Cereus 100 per St. aureus 100 Absent in 25 gr Cl Perfringens 100 per gr (not always) It is customary to use ready prepared selective and 'Oxide has been suggested throughout The organisms under examination will have dis tinctive characteristics and for routine work this should prove satisfactory Over recent years a piece of equipment called a'Stomacher'has been developed and its use has been widespread for resuscitation of bacteria. How ever it relies on the use of pre-sterilized plastic bags which cannot be recycled As these may not always be available overseas, the traditional method of preparation is submitted It must be stressed that all glassware and media must be sterilized un less stated otherwise in the method. Media to be autoclaved at 121C(15 p.s. i for 15 minutes, and glassware(pipettes and petri dishes)to be dried at 121C for a minimum of 2 hours. Disposable pre-sterilized petri dishes are available in the U. K normally. This reduces the likelihood of cross-contamination but cost and availability may preclude their use in some overseas locations Thought will have to be given to sampling frequency -say, every 2 to 4 hours or on a weight basis, say, every 250 to 500kg batch, according to the overall production Do not bulk' samples and, say, carry out daily or weekly assessments since rogue high results may put the product out of specification and give a totally distorted view More and more emphasis is now being placed on microbiology and regular structured testing will give valuable pointers as to the cleanliness of plant and soundness of raw material. Outbreaks of food contamination in recent years have highlighted the importance of microbiology in the factory Separate methods for all the above assessments followMETHODS FOR MICROBIOLOGICAL ASSESSMENTS Specifications require the following to be determined: Total Viable Count @ 30°C 100,000 per gr. ma (500,000 for onions) E. Coli 10 per gr. max. Coliforms 100 per gr. max. Yeast and Moulds 1000 per gr. max. B. Cereus 100 per gr. max. St. Aureus 100 per gr. max. Salmonella Absent in 25 gr. Cl. Perfringens 100 per gr. (not always) It is customary to use ready prepared selective Agars, and ’Oxide’ has been suggested throughout. The organisms under examination will have dis￾tinctive characteristics and for routine work this should prove satisfactory. Over recent years a piece of equipment called a ‘Stomacher’ has been developed and its use has been widespread for resuscitation of bacteria. How￾ever it relies on the use of pre-sterilized plastic bags which cannot be recycled. As these may not always be available overseas, the traditional method of preparation is submitted. It must be stressed that all glassware and media must be sterilized un￾less stated otherwise in the method. Media to be autoclaved at 121°C (15 p.s.i.) for 15 minutes, and glassware (pipettes and petri dishes) to be dried at 121°C for a minimum of 2 hours. Disposable pre-sterilized petri dishes are available in the U.K normally. This reduces the likelihood of cross-contamination but cost and availability may preclude their use in some overseas locations. Thought will have to be given to sampling frequency - say, every 2 to 4 hours or on a weight basis, say, every 250 to 500kg batch, according to the overall production. Do not ‘bulk’ samples and, say, carry out daily or weekly assessments, since rogue high results may put the product out of specification and give a totally distorted view. More and more emphasis is now being placed on microbiology and regular structured testing will give valuable pointers as to the cleanliness of plant and soundness of raw material. Outbreaks of food contamination in recent years have highlighted the importance of microbiology in the factory. Separate methods for all the above assessments follow. 245