91E-1 |
Degradation of vitamin C after alternative treatments of juices |
T. KOUTCHMA and M. Shmalts. National Center for Food Safety and Technology, Illinois Institute of Technology, 6502 S. Archer Road, Moffett Campus, Summit-Argo, IL 60501 A variety of non-thermal technologies have been proposed as alternatives to thermal pasteurization to achieve a 5-log reduction of pathogen bacteria. These alternatives promote retention of fresh juices. UV and gamma irradiation along with microwave heating are three potential treatments of juices to inactivate pathogens. To compare the effects of alternative treatments to thermal pasteurization on destruction of vitamin C in fresh juices. Titration analysis was used to measure the amount of vitamin C in carrot, orange and apple fresh juices before and after treatments. Dosage of 5, 10 and 20 kGy were used for irradiation of orange juice. UV treatment of apple and orange juices was performed in static and continuous flow reactors at 254 nm. Two microwave ovens (1300 W each) with centrally located helical coils were used in microwave heating. A water bath was used for conventional heating. D-values were calculated based on the kinetics of vitamin C destruction for each method of treatment. Gamma-irradiation of 20 kGy resulted in 89 % destruction of vitamin C in orange juice and D-value of 22.72 kGy. Destruction of vitamin C in clear apple juice after UV irradiation followed first order kinetics. The destruction of vitamin C after exposure to UV dose of 600 mJ/cm2 ranged from 30% to 40% when present at initial concentrations of 66 to 32 mg/100g. Exposure of orange and carrot juices to a similar UV dosage resulted in 18 % and 25 % destruction of vitamin C. Microwave heating of apple juice to a temperature of 83oC for 50s destroyed 20% of the vitamin C. Knowledge of the kinetics of vitamin C degradation from alternative technologies will allow optimization of microbial inactivation while minimizing vitamin C loss.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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