|Van Hekken, Diane|
|FARKYE, N. - California Polytechnic State University|
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2013
Publication Date: 7/10/2013
Citation: Van Hekken, D.L., Tunick, M.H., Farkye, N., Tomasula, P.M. 2013. High pressure processing of Queso Fresco: effects on textural and rheological properties over 12 weeks of storage. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 96:E-Suppl., 298. W214.
Technical Abstract: High pressure processing (HPP) is a non-thermal post-packaging process with the potential to improve cheese safety and shelf life because of its lethality to bacteria (spoilage and pathogens) and ability to inactivate many enzymes. Queso Fresco (QF), a high moisture Hispanic-style cheese popular in the US, could benefit from improved safety and shelf life but more information is needed to understand the impact that HPP has on the textural and rheological qualities of the cheese once it is placed in storage. A starter-free QF, made from pasteurized and homogenized milk, was vacuum packaged and then processed at 600 MPa for 3 or 10 min and stored at 4 or 10 deg C; controls were not HPP. After 1, 4, 8, and 12 wk of storage, QF were assayed for compositional, textural (texture profile analysis), and rheological (torsion and small amplitude oscillatory shear analyses) properties. After 1 wk of storage at 4deg C, the control QF consisted of 56.4 +/- 0.3% moisture, 15.4 +/- 1.5% protein, 22.3 +/- 0.3% fat, 2.9 +/- 0.1% lactose, and 2.0 +/- 0.3% salt; pH averaged 6.31 +/- 0.03. Free whey accumulated in packaging following HPP and over time resulting in decreased moisture contents (P < 0.05). Controls decreased 2.0% in moisture over 12 wk while samples lost about 2.5% moisture after HPP treatment and another 2% by the end of the study; HPP QF stored at 10 deg C tended to have the lowest moisture contents. HPP QF were harder, more rigid, and fractured at higher stress than controls (P < 0.05); QF processed for 10 min tended to be firmer than samples processed at 3 min and QF stored at 10 deg C were firmer than QF stored at 4 deg C. Within a treatment, the textural and rheological properties were stable over 12 wk of storage. Loss of free whey, considered a defect by American consumers, was enhanced after HPP treatment and affected the moisture content, texture, and rheology of the cheese. As new post-processing steps are explored, it is essential to monitor texture and rheology in order to maintain the quality traits of the cheese that are expected by the consumer.