Photochemical Protection of Riboflavin and Tetrapyrroles with Light Scattering Technology

The effectiveness of titanium dioxide (TiO?) in polyethylene films at preventing the photooxidation of riboflavin in a model solution was evaluated. Five different TiO? 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 TiO? load and thickness significantly affected riboflavin photooxidation (p<0.05). TiO? 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).

Name thesis:degree_name

Master of Science in Life Sciences

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Food Science and Technology

Department dc:contributor.department

Food Science and Technology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2012

Author dc:creator

• Hamilton, Jeffrey Hunt

Chair dc:contributor.committeechair

• Duncan, Susan E.

Committee members dc:contributor.committeemember

• Webster, Janet B.
• O'Keefe, Sean F.

• Titanium Dioxide
• Milk
• Dairy
• Oxidation
• Chlorophyll

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Dc Identifier Other

etd-07022012-170502

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/76811