14A-13 |
Feasibility trial of freezing Monterey Jack goat milk cheese in relation to shelf life and organic acid profiles |
J. H. LEE, Agricultural Research Station, Fort Valley State Univ., 1005 State University Dr., Fort Valley, GA 31030-4313 and Y. W. Park, Agricultural Research Program, Fort Valley State Univ., College of Agriculture, Home Economics & Allied Programs, 1005 State University Dr., Fort Valley, GA 31030-4313. Even though freezing cheese is not a common industrial practice, it may be essential for dairy goat industry to break the barrier of seasonal milk production and provide year-round goat cheese supply to consumers. However, research data on feasibility of freezing goat cheese is extremely limited. The study was conducted to evaluate effects of freezing on changes in shelf life and organic acid (flavor compound) profiles of Monterey Jack (MJ) goat cheese. MJ cheeses were manufactured three times at the dairy pilot plant of Fort Valley State University. Each batch was divided into two equal portions. One half was stored as fresh at 4oC for 0, 14, 28 days, and other portion was immediately frozen (-20oC), thawed after 24 h at 4oC, then stored as the same way as the fresh samples. Organic acids were determined using a HPLC (Hewlett Packard; LC-1100 Series) equipped with auto sampler, quaternary pump, vacuum degasser, and diode array detector. The column used was Hewlett Packard ODS Hypersil 5um (125 X 4 mm), and solvent was mobile phase 0.5% (wt/vol) ammonium phosphate. There was no apparent adverse freezing effect on shelf life of MJ goat cheeses. Ten organic acids (formic, pyruvic, malic, lactic, acetic, orotic, citric, uric, propionic and butyric) were positively identified and 6 additional unknown peaks were detected. Lactic and isomeric butyric acids were two major acids, and significant difference in lactic acid was found between 0 and 28 days of fresh stored cheeses. Citric acid was decreased in fresh ones, while increased frozen and thawed ones during 28 days storage. Freezing and thawing affected only lactic, citric, orotic and isomeric butyric acids on MJ cheeses, while it caused no significant effect on shelf life of the cheese which would be important for future uniform production and marketing of goat cheeses.
Session 14A, Dairy Foods: General developments in dairy technology I
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