Produzione di concentrati di sieroproteine con un impianto pilota di ultrafiltrazione. Ottimizzazione della produttività in funzione delle modalità di pretrattamento. [Production of whey proteins concentrates by an ultrafiltration pilot plant. Optimization of throughput versus whey pretreatements.]

The whey is the cheese-making industry by-prod-uci. at the present acid whey effluent of mozzarella cheese production is considered a waste water and it is disposed. Disposal increase the cheese production cost The interest of food industry is mainly focused on protein concentrates obtained through the separation of the proteins (concentrate) from permeate (lactose and salts), in the present paper are described the results obtained using an ultrafiltration (UF) plant (operating capacity 1,2 m'/h) to obtain a whey protein concentrate using acid milk whey. The processing lay-out is based on the following pre-conditioning operation: pasteurization, skimming and cold storage. After these pre-conditioning operations whey has been processed according to the following treatments: demineralization with resins (treatment A); dialysis demoralization (treatment B>; control (treatment C). Conductivity, pH, viscosity, density of whey, concentrate and permeate were monitored during the process. In addition plant operating parameters (pressure, flow and energy consumption) were recorded. From the trials it results that the pH value is the most important parameter for the proteins solubility into the gel cake present on the membranes during the UF process. The pH directly modifies the cake thickness and the diffusion coefficient of the concentrate components through the cake: the permeate flow resulted minimal for pH values near neutrality despite the operating throughput of the UF plant resulted greatly increased at 5.5 pi I value. The collected data showed a different throughput of the UF plant related to operating mode due to polarization and different severity level of fouling of membrane when working on whey with different ions content, the operating throughput resulted of about 9 kg/min of concentrate when the plant operated in treatment B. versus about 5 kg/min in treatment C and about 4 kg/min in the treatment A. Interesting indices of UF performance with the different whey treatments were found through a theoretical approach to the UF validated with the experimental trial results: with the treatment B the UF plant pointed out the best overall performance with respect to the other treatments.