Effects of extraction parameters on natural yellow pigment of canistel fruits (Pouteria Campechiana (Kunth) Baehni.)

Abstract

Extracting natural yellow pigment from canistel fruits not only took full advantages of the fruits but also contribute to diversity of natural food colorants. Extraction solvents (n-hexane, dichloromethane and mixture of n-hexane:dichloromethane (v/v 1:1)) and extraction ratios of solvent to sample (v/w) (15:1, 20:1, 25:1, 30:1) showed significant effects on pigment yields. Among solvents used, the mixture of n-hexane and dichloromethane gave the highest yield of pigment extraction with 19.13% obtained. Of four studied ratios, the lowest yield collected from the ratio 15:1; whereas the highest one obtained from the ratio 30:1. These two ratios were selected for further analyses of pigment characteristics including pH, color, solubility, total soluble solids (TSS), pH stability, thermal stability, total carotenoid contents (TCC), total phenolic contents (TPC) and antioxidant capacity (AC). Retentions of TCC, TPC and AC were evaluated at different ranges of pH and temperature. Although the ratio 30:1 resulted in a pigment yield that was twice as higher as that obtained at the ratio 15:1, the latter produced pigment samples containing significantly higher TCC than that resulted from using the former. This observation was correspondent to a significantly higher intensity of the redness (a* value) of the ratio 15:1 samples as compared to those of the 30:1 samples. Retentions of TCC and TPC were highest at neutral pH (6 to 7) and temperature ranging from 60oC to 80oC. More acidic or more alkaline pH was found to be not suitable for maintaining TCC, TPC and AC of the pigments. Also, higher temperature destroyed more TCC, TPC and AC. Key words: Antioxidant properties, Canistel, Extraction parameters, Natural pigment, Physical properties