Details:
Summary:
Commercial news inks consisting of soy or mineral oil with petroleum resins along with four colored pigments and USDA's 100% soy oil based ink consisting of modified soybean oil and pigment were subjected to biodegradation. Each ink sample was inoculated with mixed cultures of Aspergillus fumigatus, Penicillium, citrinum, and Mucor racemosus. Fermentations were allowed to proceed for 5, 12, and 25 days. Percent degradation, determined gravimetrically, was calculated based on vehicle. Results show that pigment slowed the degradation of ink vehicles, and neither the time nor the type of pigment played a significant role. In all cases USDA's ink degraded faster and more completely (for all four colors) than either partial soy oil based or petroleum based inks.