Thermal degradation of all‐trans‐β‐carotene in the presence of phenylalanine
1994
Papadopoulou, Kiriaki | Ames, Jennifer M
Solutions of all‐trans‐β‐carotene in liquid paraffin were stirred under air at 210°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‐β‐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‐β‐carotene‐phenylalanine model system at 210°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‐β‐carotene and two degradation products of all‐trans‐β‐carotene, ie 9‐cis‐β‐carotene and a furanoid diepoxy derivative. None could be detected on heating all‐trans‐β‐carotene alone, suggesting that its degradation was retarded on heating in the presence of phenylalanine.
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