Abstract #T72

# T72
Impact of membrane selectivity on the cheesemaking properties of skim milk concentrates.
A. Lauzin*1, I. Dussault-Chouinard1, M. Britten2, Y. Pouliot1, 1STELA Dairy Research Center, Institute of Nutrition and Functional Foods (INAF), Department of Food Science, Université Laval, Québec, QC, Canada, 2Food Research and Development Center (FDRC), Agriculture and Agri-Food Canada, St-Hyacinthe, QC, Canada.

Ultrafiltration (UF) is a commonly used membrane process in dairy industries, especially for cheese milk concentration. Little attention has been given to other processes such as reverse osmosis (RO) and nanofiltration (NF) for milk concentration and the cheesemaking properties of the concentrates are unknown. The objective of this work was to compare the rennet-induced coagulation kinetics as well as cheesemaking properties of UF, NF, and RO concentrated milks. Batch lots of pasteurized skim milk (SM) were concentrated by means of a pilot-scale filtration system (GEA NIROTM) operated at 50°C until a volume concentration factor of 3× using 3 different spiral-wound membranes (Synder Filtration): UF (10kDa), RO (99.4% rejection of NaCl), and NF (99 and 40% rejection of MgSO4 and NaCl respectively. Rennet-induced coagulation kinetics of concentrates was characterized by dynamic rheology and model cheeses were made to further study the cheesemaking properties. All experiments were performed in triplicate. SM concentrated using UF showed similar rennet coagulation time (RCT) and time to reach maximal firming rate (MFR) than SM (P > 0.05). However, RO and NF milks had longer RCT and MFR (P > 0.05). All concentrates presented higher firming rates than SM (P > 0.05). Model cheeses experiments showed that all concentrates had higher moisture adjusted curd yield as well as higher protein retention (P > 0.05). However, RO and NF curds had higher moisture than UF (P > 0.05). Membrane concentration process and its selectivity deeply modify the composition of milk and affect cheesemaking properties of the concentrate. This study has shown that RO and NF milks have impaired cheesemaking properties, probably because of their higher salts content. Further studies are needed to find proper ways to limit the impact of their high salts content to use these concentrates for cheesemaking.

Key Words: cheesemaking, milk concentrate, reverse osmosis