KINETICS OF ALL-TRANS-BETA-CAROTENE DEGRADATION ON HEATING WITH AND WITHOUT PHENYLALANINE

All-trans-beta-carotene was heated in liquid paraffin at 210 degrees C for 15 min in the presence and the absence of phenylalanine to assess the effect of the amino acid on the rate of degradation of all-trans- beta-carotene. The curve that represents all-trans-beta-carotene degra dation in both model systems is formed of two distinct parts that corr espond respectively, to the propagation and termination phases of an a utocatalytic reaction. The reaction over 1-15 min followed first-order reaction kinetics in both systems, and the rate constant obtained was 2.8 times lower in the presence of phenylalanine. The kinetic behavio r and the rate constant for color loss were similar to those for all-t rans-beta-carotene degradation for each model system.