Annatto-colored Poly(3-hydroxybutyrate): A Comprehensive Study on Photodegradation

Annatto natural colorant was extracted from annatto seeds (Bixa Orellana L.) by using ultrasound. Structural characterization of the extract was done by FTIR. The aim of the present work was the developement and characterization of biodegradable colored films based on poly(3-hydroxybutyrate) by using annatto colorant. The annatto content in the films was varied from 0.2 to 3.0% (w/w). The lightfastness of colored films when exposed to UVA radiation was controlled by using RGB color system. In color image processing, a pixel is often defined by three values corresponding to the tristimuli R (Red), G (Green) and B (Blue). With the addition of the annatto colorant, photodegradation of films under UVA exposure seemed to be improved. The good thermal stability of the colored film with 3.0% (w/w) of annatto colorant was confirmed by thermogravimetric analysis. Surface morphology of the colored film with 3.0% (w/w) of annatto colorant was examined by SEM prior and after 240 h of UVA exposure. The SEM micrographs suggested that annatto colorant has acted as hiding agent, reducing the photodegradation processes.