99E-24 |
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J. A. GUERRERO-BELTRAN, Dept. Ingenieria Quimica, Alimentos y Ambiental, Univ. de las Americas-Puebla, Cholula, Puebla, 72820, Mexico 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. Today, UV-C light (254 nm), a novel nonthermal technology to process foods, is currently used to inhibit or inactivate foodborne microorganisms. Generated by UV mercury lamps, UV-C light can have a germicidal effect on bacteria, viruses, protozoa, molds, and yeasts. The UV light effect on microorganisms will depend on the density and type of microorganism, and composition of the food. The objective of this study was to evaluate the UV light effect on S. cerevisiae and polyphenoloxidase inactivation in fresh mango nectar. Two “Infinity” liquid disinfection systems (Atlantic UV) were coupled in a serial arrangement to make one UV-disinfection unit. UV systems containing an inner mercury lamp (intensity of 25 mW/cm2) were also used as germicidal sources. Fresh mango nectar was processed by UV light at five flow rates (0.073 to 0.451 L/min) and five UV light doses (75 to 450 kJ/m2). Pour plating in standard methods agar and Dichloran-Rose Bengal-Chloramphenicol agar was done to assess total microbial count and S. cerevisiae, respectively. PPO activity was evaluated at 30ºC and 420 nm using a spectrophotometer. The first order kinetics modeling found that DUV values in mango nectar ranged from 27.9 – 10.9 (R2 > 0.950) and 26.0 – 11.8 (R2 > 0.962) min for total microbial count and yeast count, respectively. The maximum log reduction (CFU/ml) was 2.71 and 2.94 for total microbial count and yeast count, respectively, after 30 min of UV treatment at 0.451 L/min. DUV values ranging from 156 to 204 min were observed for PPO activity. The remaining PPO activity after 30 min of UV treatment at 0.451 L/min was 19 ± 4%. UV technology can be used for inactivation of yeasts and PPO activity in liquid food products, such as mango nectar, without using thermal treatment, which could alter taste and flavor.
Session 99E, Nonthermal Processing: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |