Thermal degradation of all-trans-beta-carotene in the presence of phenylalanine
1994
Papadopoulou, K. | Ames, J.M.
Solutions of all-trans-beta-carotene in liquid paraffin were stirred under air at 210 degrees C for 15 min in the presence and absence of various amino acids. After cooling, the absorbance values at 460 nm of model systems containing all-trans-beta-carotene and phenylalanine, cysteine or tryptophan were 34-58 times higher than that obtained on heating in the absence of an amino acid. Based on absorbance values at 420 nm, 86% of the coloured material present on heating the all-trans-beta-carotene-phenylalanine model system at 210 degrees C for 15 min was retained by the liquid paraffin on methanol extraction. The liquid paraffin phase remaining after methanol extraction was analysed by reverse-phase HPLC and three major components were identified as all-trans-beta-carotene and two degradation products of all-trans-beta-carotene, ie 9-cis-beta-carotene and a furanoid diepoxy derivative. None could be detected on heating all-trans-beta-carotene alone, suggesting that its degradation was retarded on heating in the presence of phenylalanine.
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