13.1 Introduction: principles of hygienic design
Several guidelines for equipment design have been published in order to produce
foods in a hygienically acceptable way. The principles are to prevent the
contamination of food products by substances that would adversely affect the
health of the consumer. In that respect these guidelines describe design
principles based on:
∑ smooth product contact surfaces;
∑ no dead areas; and
∑ the avoidance of condensation in the equipment.
These principles of design for equipment in the food industry are originally
based on the handling of liquids (EHEDG, 2004). However, food products with
other product characteristics may also need to be taken into consideration. This
means that the principles of design should also count for dry particulate
materials. It is important, therefore, to realise what differences there are in the
characteristics of powders as compared with liquids.
13.2 Dry particulatematerials and hygienicprocessing
In this chapter dry particulate materials, more commonly called powders, fall in
the size range of less than 10m for ultrafine powders up to a several
millimetres for agglomerates and granulates. Generally, powders are defined as
consisting of individual particles that have a diameter smaller than 150m.
Larger particulates are often composed of many smaller particles, and
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Improving the hygienic design of
equipment in handling dry materials
K. Mager, Quest International, The Netherlands