| Abstract: | Investigations into and considerations concerning the use of plastics in contact with foodstuffs. XVIth Communication: Diffusion processes in PVC hoses for food products Milk hoses of PVC react with the constituents of milk and – during the subsequent cleaning operations – also with water and cleaning solutions. The diffusion processes taking place in this connection are studied with the aid of specially designed simulating methods (rotating, milk- filled annular hose, testing apparatus reproducing the operation and cleaning of milking machines). After the tests one has determined in particular the transition of plasticiser into the liquid and the transition of fat into the plastic material, while in the case of cleaning solutions the water absorption by the plastic has been determined. The loss of plasticiser and the absorption of fatty materials depend primarily from the swelling condition of the PVC: the higher the swelling of the plastic, the easier the loss of plasticiser. During the contact with milk the then existing fatty film on the plastic inhibits water absorption, but this effect is eliminated by the cleaning operations. With increasing time embrittlement connected with cracking is observed. |
