Dairy industry generates contamination due to whey dumping from the manufacture of coagulated products. Ultrafiltration technology has been extensively studied in acid whey; however, research on sweet whey ─which is obtained from the production of fresh white cheese (Campesino cheese)─ is scarce. The objective of this study was to concentrate sweet whey proteins by ultrafiltration and to evaluate the process conditions. A polyethersulfone membrane with a molecular weight cut-off of 10 kDa was used. The effect of volumetric concentration factor between 5 and 18, transmembrane pressure between 2.5 and 5 bar was evaluated on the permeate flow, protein retention coefficient, and retention yield using a response surface methodology. The process optimization was carried out in that same range. Protein and fat were concentrated and underwent ultrafiltration; however, a less stable system was obtained. A higher concentration of protein can result in more collisions between molecules, thus generating flocculation. Whey protein concentrates had 18.2% of total solids out of which protein represents 45%.

The milk protein concentrate (MPC) has been extensively studied; however, the MPC partial demineralization through the diafiltration (DF) and its effect on MPC ability to produce milk coagulate products has not been fully explored; therefore, it was considered studying the MPC demineralization process with DF and evaluate the effect of this treatment on the compositional and textural characteristics of enzymatically and acid-coagulated products. The MPC of ultrafiltration was diafiltered by two cycles, later this MPC was used to make a fresh cheese, a set yogurt and stirred yogurt. The application of a single DF cycle removed 22.2% of the ashes and 8.12% of the MPC calcium, but no statistically significant differences were present (P> 0.05) between the application of two DF cycles. The cheeses with MPC undergone to one cycle and two cycles of DF were less hard and presented less resistance to chewing, and the set yogurt showed lower springiness values due a total solids and calcium content, that was affected by DF. These phenomena increased the coagulation time and the formation of weaker gels. The DF achieved the maximum milk demineralization in a single cycle.