Abstract #70

# 70
Structural changes and texture development in milk protein concentrates induced by high hydrostatic pressure.
Lee Cadesky*1, Markus W. Ribeiro1, Mukund V. Karwe2, Carmen I. Moraru1, 1Cornell University, Ithaca, NY, 2Rutgers University, New Brunswick, NJ.

Milk protein concentrate (MPC) and micellar casein concentrate (MCC), obtained by membrane filtration, are increasingly available. This research focuses on utilizing high hydrostatic pressure (HHP) to induce structural modifications of milk proteins in MPC and MCC and enable the creation of new textures that may find application in milk protein based products. MPC and MCC powders were reconstituted by dispersing the powders in water to 2.5 and 10% casein (w/v), and allowed to fully hydrate. The concentrates were packaged in flexible pouches and subjected to 15 min HHP treatments at 150, 250, 350, and 450 MPa, at temperatures below 25°C, in a 10 L HHP unit. Pressure induced structural changes to casein micelles in HHP treated samples were assessed by (a) evaluating the renneting behavior of the protein concentrates using dynamic rheology; (b) mineral and proteomic profiling of ultracentrifugation supernatants. The study was replicated, and significant differences among treatments were assessed by statistical analyses. In all samples, HHP treatment increased calcium levels in the serum as compared with untreated controls (P < 0.05). HHP treatments at 250 and 350 MPa resulted in levels of serum calcium over 3.5 times higher than in untreated samples. HHP above 250 MPa induced significant (P < 0.05) concentration and pressure dependent changes in MCC and MPC. In both 10% MCC and 10% MPC, HHP above 350 MPa led to the formation of weak gel structures. HHP treatment also increased G’ values of rennet gels and reduced coagulation times, which indicates a destabilization of casein micelles following pressure treatment. In 10% MCC, maximum gel strength was observed after 150 MPa treatment, with G’ of 140 Pa as compared with 45 Pa in untreated samples. For 10% MPC, HHP treatment enabled rennet coagulation, which did not occur in untreated samples. MPC renneted gels were weak, with 450 MPa treatment resulting in the strongest gels (G’ of 36 Pa). These observations suggest that HHP treatment of milk protein concentrates can be used for developing new types of dairy-based, protein rich foods with unique structure and texture.

Key Words: high-pressure processing, proteins, rheology