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    Chemical, microbiological, and physical characteristics of commercial Swiss-type cheeses
    (A V A Agrarverlag, 2009) Kocaoğlu-Vurma, N. A.; Yurdugül, Seyhun; Koca, Nurcan; Harper, W. J.; Courtney, P. D.
    High quality Swiss cheeses vary in sensory, chemical, microbiological, and physical characteristics. Determining the compositional characteristics of commercial Swiss cheeses will establish the typical range for each characteristic in cheeses intended for the American market and will complement descriptive sensory and consumer preference studies. The objective was to determine chemical, microbiological, and physical characteristics of commercial Swiss-type cheeses. Fifteen cheeses (4 US-manufactured baby Swiss, 10 US-manufactured Swiss, and one European Emmental) were analyzed for characteristics including protein, fat, moisture, salt, pH, short chain free fatty acids, and total free amino acids. Lactobacillus spp., Streptococcus thermophilus, and Propionibacterium spp. were enumerated. Physical characteristics such as hardness, springiness, and meltability were determined. The values for compositional characteristics were 23-26% for protein, 46-55% for fat in dry matter, 36-42% for moisture, and 0.7-3.4% for salt-in-moisture. The pH values ranged from 5.4 to 5.8, and the total free amino acid levels ranged from 23 to 105 mmol/kg. The bacterial counts varied widely (3-8 log CFU/g). Emmental cheese had the lowest meltability, and highest acetic and propionic acid levels.
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    High-pressure processing of Turkish white cheese for microbial inactivation
    (Int Assoc Food Protection, 2008) Evrendilek, Gülsün Akdemir; Koca, Nurcan; Harper, J. W.; Balasubramaniam, V. M.
    High-pressure processing (HPP) of Turkish white cheese and reduction of Listeria monocytogenes, total Enterobacteriaceae. total aerobic mesophilic bacteria, total molds and yeasts, total Lactococcus spp., and total Lactobacillus spp. were investigated. Cheese samples were produced from raw milk and pasteurized milk and were inoculated with L. monocytogenes after brining. Both inoculated (ca. 10(7) to 10(8) CFU/g) and noninoculated samples were subjected to HPP in a high-pressure food processor at 50 to 600 MPa for 5 and 10 min at 25 degrees C. Reductions in L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp.. and Lactobacillus spp. in both pasteurized- and raw-milk cheese samples and reductions in total molds and yeasts and total Enterobacteriaceae counts in raw-milk cheese samples increased with increased pressure (P <= 0.05). The maximum reduction of the L. monocytogenes count, ca. 4.9 log CFU/g, was obtained at 600 MPa. Because of the. highly inhibitory effect of pasteurization, the total molds and yeasts and total Enterobacteriaceae counts for the cheese samples produced from pasteurized milk were below the detection limit both before and after HPP There was no significant difference in inactivation of L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp., and Lactobacillus spp. under the same treatment conditions for the raw milk and pasteurized milk cheeses and for 5- and 10-min treatment times (P > 0.05). No significant change was detected in pH or water activity of the samples before and after HPP Our findings suggest that HPP can be used effectively to reduce the microbial load in Turkish white cheese.