FOOD SAFETY SUPPLEMENT: HYGIENE


factories; three dairies, three bakeries, two meat processing plants, one slaughter house and one food pilot test factory. Microbes on surfaces were detected based on the contact agar method using various 3M™ Petrifilms (3M Microbiology Products, St. Paul, MN, USA): Petrifilm™ Aerobic Count Plate (Petrifilm AC; 25°C, five days), 3M™ Petrifilm™ Yeast & Mold Count Plate (Petrifilm YM; 25°C, five days), 3M™ Petrifilm™ and E.coli/Coliform Count Plate (Petrifilm EC; 37°C, 48 hours). Surfaces studied were categorised as food contact surfaces (including also surfaces with indirect contact with high risk to contaminate product) and environment surfaces. Samples were taken after cleaning, just before the work shift started. The limits for the various microbes were set as loose, normal and strict scales (Table 1 opposite).


Results and discussion In the hygiene survey, the hygiene level in a factory can normally be seen from statistics of the results, which have been divided into classes e.g. good, adequate and poor, independently of if the factory is using strict, normal or loose scales. At the moment, the risk management team in the food factories have to set the limits for these hygiene levels, because there are no ISO standards in which surface hygiene limits are available8


. In setting the different surface limits,


the product produced and the shelf-life set for the products must be taken into account (Figure 1 on page 10 and Figure 2). When the limits for the various classes


are set, the spoilage sensitivity of product should be kept in mind. The more prone the product is to be spoiled, the stricter limits


should be used for the various scales. The main focus of hygiene control should of course be on the food contact surfaces. However, environ ment surfaces can also be a part of the contamination routes e.g. through cross contamination. The microbes found on environmental surfaces e.g. floors, walls, doors and shelves can have an impact on product quality especially in open processes. The microbes can be transported from the environmental surfaces to the food contact area by draught or by personal movements e.g. in slicing of heat-treated meat products in semi- open equipment. Note that the hygiene of the environmental surfaces can also affect the product produced in closed processes e.g. in dairies. During processing of milk in big tanks, air is fed into the tank when product is pumped away. In the case that the air filters are not properly maintained,


microbes can be


transported into the system and the product can thus get spoiled by microbes from the air.


Conclusion and recommendations Our recommendation for testing the surface hygiene in the food processing area is to use aerobic bacteria, yeasts, moulds and coliforms as indicators. Information on aerobic bacteria is especially needed when products with long self- life are produced. In relatively hygienic facilities,


“The more prone the product is to be spoiled, the stricter limits should be used for the various scales ”


the aerobic bacterial count also reveals places, which might need improvement. The coliform count is traditionally considered as an indicator for hygiene, since the presence of coliforms refer to poor hygiene. The fungal count is giving information on possible moist problems and lowered air quality. In food hygiene surveys, specific microbes e.g. Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Escherichia coli can be added according to the risks of the products produced.


FIGURE 2The share of good, adequate and poor hygiene on food contact surfaces in 10 food factories as a total of: a) 45, b) 47 & c) 49 surfaces in three dairies, d) 23, e) 15 & f) 29 surfaces in three bakeries, g) 50 surfaces in a food pilot factory, h) 40 & i) 26 surfaces in two meat factories and j) 76 surfaces in a slaughterhouse. See Table 1 for limits used


newfood Volume 15 | Issue 1 | 2012


Acknowledgement The authors are grateful to the European Hygienic Engineering & Design Group for providing a travel scholarship which enabled the presentation of this paper at the EHEDG World Congress on Hygienic Engineering & Design in Macedonia in September 2011.


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