Secondary contamination is said to cause more than a half of food poisoning cases a big problem in food hygiene management. Basic prevention of secondary contamination requires measures to be decided after closely examining each cooking step involving humans and finding out where secondary contamination occurs or how secondary contamination could readily occurs. Hence, we incorporated viewpoints of industrial production. We used the modified analysis to perform a behavioral contamination analysis of cooking steps and actions in school lunch preparation in order to find where secondary contamination is apt to occur. In addition, we examined the whole cooking procedure involving food materials, hands and fingers, and machinery and equipments.
As a result, we found the followings:
(1) Secondary contamination was likely to occur in steps taken in sub-hygienic areas of a non-contaminated zone. In other words, considerably contaminated food materials might be handled in a sub-hygienic area, which belongs to a non-contaminated zone. Therefore, it is necessary to recognize that the designation of a work area does not match the contamination level of food of materials used in the work area.
(2)Hands and fingers handling fresh food materials in a sub-hygienic area inevitably touch equipments without being washed. Such actions need to be carefully watched from the viewpoints of the prevention of secondary contamination. Examples of such actions include touching faucets and levers to adjust water flow of tap water, touching knocbs to adjust the fire power of a gas range during heating for cooking, touching switch panels of various cooking equipments, and touching the door knob of a refrigerator to take food materials out.
Considering the above, the following measures are important for a kitchen and need to implemented urgently: the preparation of a manual for cleaning the contact points mentioned in (2) to make the oractice customary and thorough preparation in advance for efforts to decrease the frequency of touching knobs of a storage chamber. The behavioral analysis sheet devised this time makes it possible to find at a glance how levels of contamination change and which parts of hands and fingers touch equipments. We believe that further improvement of the sheet will lead to its use not only as a tool for hygiene managemant but also as a tool for hygiene aducation.