4.1 Introduction: disinfection methods
In the food industry worldwide millions of tonnes of safe and healthy food are
produced every year, by many people using a large amount of equipment. In
producing food, the equipment used gets soiled by both product and
microorganisms. In order to avoid recontamination of the fresh product due to
fouled surfaces, each piece of equipment or processing line needs to be cleaned
and disinfected at regular intervals. Therefore, cleaning and disinfection are
important unit-operations that are carried out in each food factory on a regular
basis. Within the dairy industry, for example, cleaning and disinfection is carried
out on a daily basis, sometimes several times a day. For condiments the
frequency differs per batch of product; however, the equipment is cleaned and
disinfected usually after 8±16 hours operation. In the beverage industry, because
of the acid character of fruit juices and soft drinks, cleaning and disinfection is
applied after 60±100 hours of production.
Disinfection is defined as the treatment of surfaces/equipment using physical
or chemical means such that the amount of microorganisms present is reduced to
an acceptable level (Krop, 1990; Donhauseret al., 1991). Prior to disinfecting,
cleaning of the surface is necessary to remove organic compounds adhered to the
surface. Without proper cleaning, disinfection is useless, as remaining product
will inactivate the disinfecting agent and microorganisms present will survive the
disinfecting treatment. In practice 90±95% of the microorganisms present are
removed by an efficient cleaning protocol (Krop, 1990). Disinfection reduces the
amount of remaining microorganisms. This means that, in general, a disinfected
surface/piece of equipment is not sterile and means that disinfection is not equal
to sterilisation where viable microorganisms can no longer be detected.
4 Pathogenresistanceto sanitisers...
A. J. van Asselt and M. C. te Giffel, NIZO Food Research,
The Netherlands