Antioxidant and prooxidant activities of β-carotene in accelerated autoxidation and photosensitized model systems

Antioxidant or prooxidant activity of beta-carotene was studied in autoxidized or methylene blue photosensitized lard using the depletion of headspace oxygen, p-anisidine value (p-AV), or a modified DPPH methods. beta-Carotene of 1.25 and 2.50 mu M significantly decreased headspace oxygen and beta-carotene from 0.25 to 2.50 mu M increased significantly p-AV in lard oxidized at 60A degrees C for 60 h (p < 0.05), implying beta-carotene acted prooxidantly. beta-Carotene under 0.25 mu M in oxidized lard did not decrease the absorbance of DPPH significantly (p > 0.05), while 1.25 and 2.50 mu M beta-carotene decreased the absorbance of DPPH significantly (p < 0.05), indicating beta-carotene over 1.25 mu M accelerated the formation of radical scavenging compounds from oxidized lipids (RSOLs). However, all the concentration of beta-carotene did not cause significant changes in DPPH absorbance and headspace oxygen content (p > 0.05) in photosensitized lard at 40A degrees C for 24 h, indicating antioxidant properties of beta-carotene in photosensitization.