EVALUATION OF COLOUR VALUE AND PIGMENT CONCENTRATION OF CAPSICUM EXTRACTS

摘要

This study on capsicum extracts is designed: (1) to evaluate the response of the major red and yellow pigments to the colour value; (2) to investigate the accuracy of spectrophotometric methods for the estimation of the red, yellow and total pigments; (3) to confirm the trustworthiness of commonly adopted conversions of colour value to pigment concentration and (4) to re-examine the existence of the alleged equilibrium between the red, yellow and total pigments. Firstly, it is shown that the colour value as measured by the classical EOA, ASTA or MSD-10 methods cannot be accepted as a quality determinant of capsicum extracts. Secondly, the spectrophotometric methods of BENEDEK, FEKETE & co-workers and HASPEL-HORATOVIC & HORICKOVA (1976) fail to quantify the red, yellow and total pigments accurately. Thirdly, no equilibrium exists between the red, yellow and total pigment concentrations. However, the MSD-10 colour value divided by 1600 or the ASTA colour value by 40 approaches the total pigment concentration as disclosed by HPLC method. To quantify the red and yellow pigments, HPLC method is par excellence.