99E-6 |
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N. MOHD ADZAHAN, R. W. Worobo, and O. I. Padilla-Zakour. Food Science and Technology, Cornell Univ., 630 W. North St., NYSAES, Geneva, NY 14456 Juice producers face the challenge of optimizing issues related to food processing, safety and quality to satisfy consumers' preferences. Previous studies have shown that ultraviolet (UV) irradiation of juices leads to the loss of ascorbic acid. Since juices are often fortified with vitamins to enhance its nutritional content, studies on the level of exposure to UV and the extent of vitamin loss is essential. Our objective was to evaluate the rate of degradation for ascorbic acid, thiamine and pyridoxine in water solutions and apple juice when exposed to UV at various doses. UV treatment was performed using a CiderSure model 3500 UV with various flow rates ranging from 2.8 kg/min to 15.8 kg/min. The UV dose (4.3 to 78.3 mJ/cm2) was calculated based on the irradiance and exposure time. Samples of individual vitamin solutions (10 to 25 mg/100ml), a mixture of vitamins, malic acid and sucrose solutions, and apple juice were treated and analyzed by HPCE. All duplicate samples were protected from heat, light, flushed with nitrogen after treatment and analyzed immediately. UV treatment resulted in consistent losses of vitamins with increasing levels of dose. The degradation pattern fits the first order reaction model. Ascorbic acid was most affected by UV with fortified apple juice showing 40% loss at about 11 mJ/cm2, while at approximately the same dose juice with thiamine and pyridoxine lost not more than 17% and 4% respectively. The degradation rate for samples within thiamine and pyridoxine groups was similar but the rate for ascorbic acid in juice was faster than water solutions, even though there are many UV absorbing compounds in apple juice. UV offers an alternative for safe treatment of minimally processed juices but healthful compounds such as vitamins can be significantly reduced by this process, hence the need to minimize UV dose.
Session 99E, Nonthermal Processing: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |