Microbiological Analysis and Quality Control

Several major factors need to be considered. Firstly, have any micro-organisms present in the ingredients been destroyed Secondly, if they have not been destroyed, are they capable of growth and/or toxin formation Thirdly, is there any point in the process where micro-organisms could be introduced or reintroduced, and if such an introduction takes place, could they grow or form toxin  

Much of the laboratory time (perhaps 70-80%) will be taken up with routine samples taken from the processing line, and examination of these samples is designed to detect any problem. The preparation of samples for analysis takes a long time, therefore routine samples should be taken on days when analysis may be started and finished conveniently. Details of bottlenecks and problems are given. The remainder of the time will be spent examining any samples involved in the outbreak of a foodborne disease and dealing with consumer complaints. 

There are several objectives for in house quality control. Microbial testing of raw materials, intermediate, and finished products allows the effectiveness of microbial control during processing to be assessed, whilst another major consideration of quality control is the predicted shelf life of the product. Quality control requirements, i.e. what to test for, how frequently to test, and what is acceptable, are usually management decisions based on experience, and are not mandatory requirements applied by an outside body.  

Tests for coliforms or Enterobacteriaceae are useful for monitoring the effectiveness of mild heating (pasteurisation) and as an indicator of recontamination. The presence of coliforms does not indicate faecal pollution as there are a 

Enterococcus (Streptococcus) faecalis is not widely used as an indicator in food microbiology. It is useful, however, as it has a relatively high resistance to high temperatures, freezing, drying and disinfectants/detergents. It may therefore be preferred as an indicator in certain situations, as it is more resistant than the Enterobacteriaceae. 

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