PROCESSING METHODS TO MODIFY THE LEVELS OF BIOLOGICALLY ACTIVE COMPOUNDS IN MILK AND CHEESE
Location: Dairy and Functional Foods
Title: Effects of high pressure processing on the composition, functional and rheological properties of fresh Queso Fresco
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 3, 2011
Publication Date: July 13, 2011
Citation: Van Hekken, D.L., Tunick, M.H., Kwoczak, R., Tomasula, P.M. 2011. Effects of high pressure processing on the composition, functional and rheological properties of fresh Queso Fresco. American Dairy Science Association Abstracts. 94:(1)536.
Although Queso Fresco (QF), a popular high moisture Hispanic-style cheese sold in the U.S., is made from pasteurized milk it is subject to post pasteurization bacterial contamination. High pressure processing (HPP) of cheese is being considered because of its lethality to bacteria and potential to extend shelf life. However, little research has been performed to determine the effects of HPP on the functional and rheological properties of QF. Fresh QF, made from pasteurized homogenized milk without starter cultures, was cut into 45x45x150mm3 blocks, double packaged in vacuum bags, and received the following HPP treatments: 200, 400, or 600 MPa for either 0, 5, 10, or 20 min; samples were stored at 4 deg C but were warmed to an internal temperature of either 22 or 40 deg C just prior to HPP treatment. Between days 6 and 10, samples were assayed for compositional, functional (meltability, initial color, and change in color after heating) and rheological (texture profile, torsion, and small oscillatory shear analyses) properties. The moisture content of the cheese was stable when QF was processed at 22 deg C but whey was forced out of the cheese matrix and accumulated in the packaging when processed at 40 deg C. HPP of QF at 22 or 40 deg C did not affect the non-melt property, the initial bright white color, or the changes in color after heating of QF. Compared to HPP at 22 deg C, conducting HPP at 40 deg C resulted in QF having higher values for hardness, chewiness, cohesiveness, shear stress and shear strain. Cheese samples had variable responses to HPP as pressure and length of treatment increased; springiness and cohesiveness were lowest for 600 MPa treatments, shear rigidity at the point of fracture was highest at 600 MPa, and HPP treatment had little effect on viscoelastic properties. High pressure processing altered the rheological properties of QF and, when conducted at 40 deg C, resulted in excessive wheying-off. As new safety intervention processes are explored, it is essential that the quality traits of the cheese be maintained.