Poly(lactic acid) film incorporated with marigold flower extract (Tagetes erecta) intended for fatty-food application

Bilayer functional film made of poly(lactic acid), PLA incorporated with 2 wt.% marigold flower extract containing astaxanthin (PLA2M) was fabricated by using a blown-extrusion process. The release of astaxanthin, a keto-carotenoid antioxidant, from the PLA-based film towards 95% ethanol (ETOH) was investigated at 30 and 40 °C. PLA and PLA2M that had been in contact with 95% ETOH at 30 and 40 °C were also investigated for their optical, thermal, structural, molecular weight and barrier properties. PLA2M showed approximately 21% reduction in its water vapor permeability (WVP) as compared to PLA (control bilayer functional film). No significant differences were observed between both PLA and PLA2M in terms of their thermal properties and O2 permeability. Molecular weight of PLA2M had a slight decreased than that of PLA after processing. A significant change was observed in the IR spectra of PLA2M especially for the carbonyl stretching (1749 cm−1), and -C-O-C aliphatic ester bending (1132 cm−1), which due to the structure of astaxanthin that consists of polyunsaturated alkenes and carbonyl group. Diffusion of astaxanthin from PLA films into 95% ETOH at 30 and 40 °C were 12.7 and 22.8 × 10−11 cm2/s, respectively. New crystal domains were formed for the samples exposed to 95% ETOH at 30 and 40 °C due to solvent induced crystallization, with higher temperature inducing larger crystallization. Pouches made of PLA2M were able to maintain the freshness of soybean oil at 30 °C, under light exposure to less than 5 days per guideline by the Codex Alimentarius (<10 milliequivalent/kg), and could be attributed to the slow release of astaxanthin.