Title page for ETD etd-07022012-170502

Type of Document Master's Thesis
Author Hamilton, Jeffrey Hunt
Author's Email Address jhh3m@vt.edu, jeffhamilton08@gmail.com
URN etd-07022012-170502
Title Photochemical Protection of Riboflavin and Tetrapyrroles with Light Scattering Technology
Degree Master of Science In the Life Sciences
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Duncan, Susan E. Committee Chair
O'Keefe, Sean F. Committee Member
Webster, Janet B. Committee Member
  • Titanium Dioxide
  • Milk
  • Dairy
  • Oxidation
  • Chlorophyll
Date of Defense 2012-06-18
Availability unrestricted
The effectiveness of titanium dioxide (TiO2) in polyethylene films at preventing the photooxidation of riboflavin in a model solution was evaluated. Five different TiO2 loads (0.5-8.0 wt%), each at 3 different thicknesses (50-100 um) were evaluated. A photochemical reactor, equipped with a 350W mercury lamp, provided full spectrum light or narrow bandwidth wavelength exposure, using filters allowing transmission at 25 nm wavebands at maximum peak height at 450, 550, or 650 nm. Riboflavin concentration was measured by HPLC over 8 hours of exposure. Increased TiO2 load and thickness significantly affected riboflavin photooxidation (p<0.05). TiO2 load had more influence on protection provided to riboflavin than did film thickness. Film opacity correlated linearly with decreased photooxidation (R2 of 0.831 & 0.783 for full spectrum and 450 nm bandpass-filter sets, respectively). Riboflavin photooxidation proceeded most rapidly with the full spectrum exposure (light intensity 118 ± 17.3 mW). Photooxidation occurred in the 450 nm bandpass-filter, but not for 550 & 650 nm sets (light intensities of 2.84 ±0.416, 3.36 ±0.710, and 0.553 ± 0.246 mW, respectively). Effect of fluorescent light-exposure (2020-1690 lux) on the same system was monitored over 2 days. Riboflavin degradation in the photoreactor proceeded ~300 times faster than under fluorescent lighting. Riboflavin degradation was found to significantly increase with the addition of chlorophyll-like tetrapyrroles (p<0.05). Riboflavin was found to significantly decrease the degradation rate of the tetrapyrroles pyropheophytin a and pheophytin a (p<0.05). The decrease in rate was not significant for chlorophyll a (p>0.05).
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