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R. V. POTINENI and D. G. Peterson. Dept. of Food Science, Pennsylvania State Univ., 111 Borland Lab., University Park, PA 16802 Numerous flavor-matrix interactions can result in significant flavor losses in food products during storage and ultimately affect consumer acceptability. Previous studies have reported that in fluid milk products, protein binding to specific flavor compounds, such as benzaldehyde, was a key reason for flavor loss during storage. However, the presence of different intrinsic enzymes in milk may also result in flavor degradation. Therefore, flavor stability may be directly correlated to level of heat treatment in such milk-contain food products. The goal of this research was to investigate the influence of the heat treatment level on benzaldehyde degradation in fluid milk. Benzaldehyde added (110ppm) to four different kinds of heat processed whole milk [raw, pasteurized, pasteurized which was additionally heated to 100ºC (PAH) and UHT] which were stored at 5ºC. Sodium azide (200ppm) was added as an antimicrobial agent (one additional pasteurized milk sample without sodium azide). The concentration of benzaldehyde and benzoic acid were determined at day 0, 1, 2, 4, 6 by quantitative gas chromatography/mass spectrometry in selective ion monitory mode (GC-MS-SIM). The microbial load was also determined on days 0, 2 and 6 (TPC). Over the six-day storage period more than 80% of the benzaldehyde content was converted (oxidized) to benzoic acid in raw and pasteurized milk, while no change in the benzaldehyde concentration was found in PAH and UHT milks. Furthermore, direct comparison of the pasteurized milk samples with and without azide, reported the oxidation rate was more rapid after day 2 for the azide-containing sample. This difference may be attributed to less oxygen utilization by the microflora as the TPC analysis reported no microbial counts in the milks containing azide, after day 2. Flavor stability in fluid milk-containing products can be improved for compounds such as benzaldehyde by processing at temperatures higher than traditional pasteurization.
Session 46, Dairy Foods: General
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