32.1 Introduction
When assessing the measures needed to reach a level of sufficient hygienic
conditions in food production plants, not only the processes and their results but
also the attendant circumstances such as the type and quantity of the required
chemicals, water consumption, disposal of chemicals and water, and, last but
not least, the costs for the total cleaning process have to be taken into account.
Additionally, it has to be considered that the cleaning processes, including the
chemicals to be used, must be adapted to the specific requirements. In a dairy,
due to different soiling, for example, a staple tank for raw milk or a bulk milk
tanker requires a different cleaning process from a pasteurizing plant, a plant
for ultraheating consumer milk, a plant for the manufacture of yogurt, or a
cheese manufacturer. However, regardless of the difference among the
processes, at a certain point the question of disposal and the related environ-
mental pollution arises for all cleaning agents. So long as a substance contained
in the waste water is biologically degradable it can be discharged without any
problems into the municipal (or, if present, in the company-owned) sewage
treatment plant, and be adequately processed. If small quantities of non-
degradable components occur in the form of waste-water sludge, most of the
remaining components can be discharged in the form of cleaned water into the
natural cycle.
The chemicals used in conventional cleaning processes in the food industry
are primarily biologically non-degradable substances such as sodium or calcium
hydroxide, and nitric and phosphorous acids, which have to be neutralized
because of their pH values (12 to 13 or 1 to 2) to a pH value of 8 to 9 by simple
32 Enzymaticcleaningin foodprocessing
A. Grasshoff, Federal Dairy Research Centre, Germany