EFFECTS OF CONCENTRATION ON FOULING OF WHEY

The aim of the experiments was to study the fouling effects of concent rated whey having various solids content on the hot surface of a model installation. Deposits were formed on the wall of a tubular test sect ion of which the temperature, as well as that of the product, was regu lated. Steam injection into the product ensured instantaneous and unif orm heating even if it was highly concentrated. The deposits were prod uced in a specially constructed unit which made it possible to assess them by optical methods, to determine their mass and to analyse them c hemically. Deposits formed from whey products of increasing solids con centrations were heaviest when the concentration was of about 25%. A c haracteristic of the formation of the heaviest deposits is the volumin ous structure having a high amount of porous protein which contains a large quantity of lactose, too. At higher solids concentrations of the product (up to 35%) the structure changes from a spongy, weak fouling layer to compact, firm, strongly adhering deposits and the total amou nt decreases drastically. At the same time there is a change in the co mposition of deposits. Their main constituents are now proteins, the p roportion of lactose decreases considerably and the proportion of salt s increases and may reach 15% in the case of highly concentrated produ cts.