91E-14 |
The effect of browning and suspended particles on the UV treatment of apple juice/cider |
T. Koutchma1, R. ENGLERT1, C. Adhikari1, and S. Kucuk, V2. (1) National Center for Food Safety and Technology, Illinois Institute of Technology, 6502 S. Archer Road, Moffett Campus, Summit, IL 60501, (2) Chemical Engineering, Illinois Institute of Technology, 10W 33rd Street, #127, Chicag, IL 60616 FDA approved the use of ultraviolet (UV) irradiation for inactivation of pathogenic microorganisms in juice products. Apple cider is a liquid with a high UV absorptivity, and contains both dissolved and suspended solids. Juice composition, solids size and concentration, and color due to browning reactions (enzymatic/non-enzymatic) can have a major effect on the UV transmission and disinfection capability. To optimize effectiveness of UV treatments for use in diverse types of apple juice/cider, information is needed on the effect of critical product parameters on UV light penetration. To characterize the effect of absorbance, suspended solids and non-enzymatic browning on the absorptive properties of apple juice/ cider in the UV light spectrum. Kinetics of the browning reaction in fresh apple juice was studied by measuring an increase absorbance using a double–beam Perkin Elmer UV-Vis spectrophotometer at 254 and 283.9nm (absorbance maximum for Hydroxy Methyl Furfuraldehyde). Turbidity was measured using HACH 2100N Turbidimeter. Particles size distribution in apple cider was estimated in “Microtrac” analyzer. Estimation of the true absorbance of apple cider involves separation of absorbance due to soluble substances, absorbance due to particles, and scattering due to particles. The absorbance of apple cider solution was lower compare to clear commercial apple juice. Turbidity was in the range of 1000 to 1500 NTU for apple cider and 2 or less for clear apple juice. Apple cider particles showed bimodal distribution: 1-26 mm with an average of 7.6mm and 30-592 mm with an average of 225 mm. Color development in apple juice due to browning increased the absorbance of untreated samples of apple juice by 40-50%. The effect of suspended particles and browning of apple juice/cider should be considered when calculating UV dose delivered during UV treatment of juice/cider.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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