58-2 |
Modeling whey drainage from feta cheese using Darcy’s law |
M. S. KALAMAKI, M. J. McCarthy, and K. L. McCarthy. Dept. of Food Science & Technology, Univ. of California, Davis, 1 Shields Ave., 226 Cruess Hall, Davis, CA 95616 Whey drainage, often described as syneresis, is common in soft, high moisture cheeses such as feta, cream, blue and Cheshire cheese. This drainage is considered a defect because it results in overall moisture loss and may lead to dryness and reduced consumer acceptance. To characterize this type of moisture loss, the time dependent internal moisture distribution of feta cheese was experimentally evaluated and mathematically modeled using Darcy’s law. Over a time frame of 3 hrs, changes in the moisture distribution of a 65 x 65 x 31 mm3 piece of feta cheese were experimentally determined using a magnetic resonance imaging (MRI) spin echo based pulse sequence. The moisture content of the feta was evaluated at each imaging time in order to determine the hydraulic diffusivity (D), which characterized the convective draining process. Initially, the moisture content of the feta cheese was relatively uniform at 0.47 (w/w). As fluid drained through the lower surface, the transient moisture distribution was characterized by the hydraulic diffusivity, which ranged from 2.6-3.2 x 10-9 m2/s for the replicates. As this drainage process is considered a defect, this characterization is the first step to understanding ways to reduce moisture loss and maintain cheese quality.
Session 58, Food Engineering: Transport processes and kinetics
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