99E-26 |
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D. BERMUDEZ-AGUIRRE, Biological Systems Engineering, Washington State Univ., 213 LJ Smith Hall, Pullman, WA 99164, T. Mobbs, K. Versteeg, Food Science Australia, 671 Sneydes Road, Werribee, Vic, 3030, Australia, and G. V. Barbosa-Cánovas, Dept. of Biological Systems Engineering, Washington State Univ., 220 L.J. Smith Hall, PO Box 646120, Pullman, WA 99164-6120. Ultrasound is an emerging technology that has been tested on some foods successfully, as microbial inactivation seems viable. But few studies have been concerned with the physicochemical and nutritional changes in ultrasonicated food. The objective of this work was to analyze the physicochemical properties of milk (pH, acidity, and color) and the nutritional components (protein and butter fat) of thermal and thermo-ultrasonicated milk. Samples were treated at constant temperature (63º C) and different amplitudes of ultrasonic wave (0, 30, 60, 90 and 100%), in an ultrasonic processor Hielscher® UP400S (400 W, 24 kHz) with a 22 mm probe. Proximal analysis was carried out in Lacticheck® equipment. Results show that pH and acidity were similar for thermal (6.73 ± 0.05, 0.131% ± 0.006) and thermoultrasonic treatments (6.63 ± 0.05, 0.148% ±0.005). Acidity and pH were constant and they remained this way for more than 14 days. Regarding color, an important change was observed in the ultrasonicated milk. These samples showed higher values in the parameter L. Thermo-ultrasonicated samples were whiter (92.19 ± 0.27) and showed a better parameters of color and homogenization over 14 days, compared with thermal treated milk (88.11 ± 0.29) and raw milk (86.99 ± 0.97). As for nutritional properties, butter fat content was higher for ultrasonicated milk (4.26% ± 0.04). Results suggest that the fat globules may have broken up in the milk with use of ultrasound, improving the availability of fat. Protein content of thermoultrasonicated milk was lower than in raw milk, but levels of ultrasonicated samples were around 3.02% (±0.02), which is the normal protein content of raw milk. Nonfat solids were decreased in ultrasonicated samples and additional water was detected. Based on these results, it can be concluded that thermo-ultrasonic treatments are a good option for pasteurization of milk from the physicochemical and nutritional points of view.
Session 99E, Nonthermal Processing: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |