Research on natural pigments has been driven by mounting evidence that synthetic dyes can
cause deleterious health effects. Betalains, excluding anthocyanins, have been proposed as
natural alternatives to synthetic dyes; however, incorporating natural pigments into the food
industry is challenging because they are less stable than their synthetic counterparts.
Accordingly, the objective of this study was to explore the feasibility of using pitaya peel flour,
a coproduct discarded in the environment after processing this fruit, as a natural dye. Initially,
the extraction process was optimized by comparing extracting solutions (50% methanol, water,
95% ethanol, and 80% acetone) in different pH environments (4.0–9.0) and measuring their
absorption after extraction at varying wavelengths (485, 535, and 700 nm). The optimum
conditions were then used to extract the pigments from the pitaya peel, and their stabilities were
studied at 15-day intervals, over a 60-day period, under different temperature conditions
(ambient, frozen, and refrigerated) and in the absence and presence of light. Extraction with
50% methanol or water offered the best yields, and there was no significant effect of pH on the
process. The highest absorbance values were observed at 485 and 535 nm, with the highest
absorbance obtained at 485 nm under optimal conditions. The pigments extracted from the
pitaya peel flour were the most stable when the extract was frozen in the absence of light, and
could remain stable over a 15-day storage period.
|
