Analysis of natural colourant extracted from the pericarp of passion fruit

Abstract

The pericarp of passion fruit is typically discarded before consumption. We aimed to demonstrate that pigments extracted from the pericarp could be used as natural colourants. We focused on the stability of the dyes in response to heat, light, and storage, which is the most pressing problem associated with natural colourants. The stability of the pigment in solutions was affected by certain factors. However, colour measurements confirmed that for test samples in powder form or those covered by a coloured commercial plastic bag or light shield, the pigments remain stable with no noticeable colour change. The pigment extracted from the pericarp included anthocyanins such as cyanidin-3-glucoside, peonidin-3-glucoside, callistephin, and cyanidin-3-rutinoside, which have 3-O-glycoside bonding of the C-ring. They were not found in the passion fruit pulp or seeds. The colour value of the pigment was lower than that of the same amount of red cabbage dye or purple sweet potato dye, which are typically used in food manufacturing. The pigment extracted from passion fruit pericarp was used to dye processed food such as jelly, which was coloured pink to red depending on the amount of pigment used. The passion fruit pericarp could be used as a low-cost natural red colourant.