C W Donnelly

In addition to prerequisite programmes which include standard sanitation operating procedures, good manufacturing practices and good agricultural practices, a hazard analysis critical control points (HACCP) programme can identify and control potential hazards to ensure food safety. The seven principles of HACCP (hazard analysis, identification of critical control points (CCPs), establishment of critical limits for the CCPs, identification of monitoring procedures for the CCPs, record keeping, corrective actions and verification of the process) must be identified as components of an effective HACCP plan. Raw milk quality is important in producing all cheeses, but particularly for cheeses manufactured from raw milk. Low bacterial counts and low somatic cell counts are the key indicators of milk quality, and as their numbers increase, there is a higher risk for contamination of milk and cheese with pathogens. Monitoring and controlling bacterial and somatic cells counts in milk should be components of a HACCP programme to ensure product safety. As rapid, cost-effective methods become available for detection of bacterial pathogens in raw milk, the use of specific pathogen testing could become part of a HACCP programme. In general, when raw milk bacteria and somatic cell counts are high, there will be other negative impacts on cheese quality that may reduce consumer acceptability and cheese yield [48]. In the manufacture of most artisanal cheeses, the time from milking to cheesemaking is very short and in some cases the milk is made into cheese immediately on the farm without cooling. Minimising the time from milk collection to the initiation of cheesemaking reduces the opportunity for the growth of undesirable bacteria in raw milk. Conversely, when milk is cooled and held in transport, the opportunity for pathogen growth, particularly growth of psychrotrophic pathogens, is increased.

The European Community Directives 92/46 and 92/47 contain regulations for the hygienic production and marketing of raw milk, heat-treated milk and milk-based products. These regulations establish hygienic standards for raw milk collection and transport that focus on issues such as temperature, sanitation and microbiological standards, enabling production of raw milk of the highest possible quality. Raw cow's milk must meet quality standards, e.g. a standard plate count at 30 0C of <100 000cfuml_1 and somatic cell counts of <400 000 per ml of milk. To meet these and other established standards, countries employ HACCP principles in the production of fluid dairy products. This involves identification of sites to be monitored and evaluated to ensure that products are produced under the correct conditions, as well as the development of critical limits established by valid and verifiable parameters. In the case of fluid milk products, many processors have identified length of shelf-life as a critical limit. Shelf-life is influenced by a number of factors including cleaning and sanitising of pipelines and milking equipment, condition of raw milk used to produce product, and storage temperature. Pasteurisation [11] will eliminate some of the indigenous microflora in the raw milk including pathogenic bacteria; however, thermoduric organisms survive pasteurisation. Post-pasteurisation contamination of milk is problematic if the processing/packaging environment is not maintained. Moreover, many contaminants, including Listeria, are able to form biofilms which protect them from cleaning and sanitising agents. Some regulations, such as those of the EU, have established microbiological limits at the sell-by date for products such as cheeses. With respect to regulations which govern the use of raw milk for cheesemaking, limits have been established for Staphylococcus aureus in raw milk. Finished cheeses must meet specific hygienic standards, in which case the presence of S. aureus and Escherichia coli indicate poor hygiene.

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