The material of each hose, in addition to its basic component i.e. elastomer (rubber hoses) or polymer (plastic hoses), contains many additives ensuring the appropriate processing properties of a raw material and the best possible mechanical and chemical properties of a finished hose. These include various types of crosslinkers, plasticisers (softening agents), fillers, stabilisers, antioxidants, dyes etc. Impurities coming from the raw materials may also be present.
When the hoses are used in food production and processing, the material of their internal layer is in direct contact with the food substance that flows through the hose – from the beginning to the end of the whole process, so until the cleaning of the hose or the entire system is finished. As a result of this contact, the additives are extracted (drawn) from the rubber or plastic compound and then they pass (permeate, migrate) into the liquid food substance, acting as a solvent. The amount of substances that migrate into food depends primarily on the type of hose material, type of additives, chemical properties of the food substance flowing through, time and temperature.
The additives contained in the food substances may be harmful to human health. Besides, they may alter the organoleptic properties of a food product (e.g. taste or smell). Therefore, the requirements for food contact materials focus on:
- permitted amount of a given additive – some of which are totally prohibited;
- permitted migration of additives into food simulants – model fluids substituting specific types of food