surface with axes defining the probability of acceptance/rejection, the
proportion of marginally defectives in a lot, and the proportion of
defectives in a lot (Figure 11.7).
Microbiological criteria using attributes sampling plans for different
foods have been produced by a number of organizations and some
examples of these are given in Table 11.2. As is clear, the stringency of
the sampling plan varies with the type of food and the organism being
sought.
In 2006 a regulation came into force in the countries of the EU (2073/
2005) setting down microbiological criteria for some foods based on
attribute plans. This consolidated a number of previous regulations and
criteria. It also introduced two types of criterion: food safety criteria and
process hygiene criteria. If foods fail to meet food safety criteria they
should not be placed on the market or withdrawn from sale. Failure to
meet process hygiene criteria is less serious but would necessitate a review
of food safety management procedures with a view to improving product
quality. The criteria are not intended as quality control measures in
Figure 11.7 Operating characteristic surface for a three-class plan.n¼10,c¼ 2
(Reproduced with permission from Jarvis (1989)
404 Controlling the Microbiological Quality of Foods