Detection of betacyanins pigment stability fromHylocereus polyrhizus(Weber) Britton & Rose fruit pulp and peel for possible use as natural coating

Purpose The purpose of this paper is to evaluate the potential of betacyanin pigment extracted from Hylocereus polyrhizus fruit pulp and peel as a natural colorant and to observe the effects of pH and light on betacyanin contents. Design/methodology/approach In this study, pigment from the pulp and peel of H. polyrhizus fruits was extracted using 80 per cent methanol and 80 per cent acetone. Effects of pH and light exposure during storage on betacyanin content were evaluated. The betacyanin extract, mixed with 20 per cent poly(methyl methacrylate) and coated onto glass slides, was tested with different concentrations of sodium hydroxide (NaCl) to determine its durability. An ultraviolet (UV)–visible spectrophotometer was used for analyzing the betacyanin content. Findings Betacyanin pigment extracted from pulp using 80 per cent acetone as the solvent at pH 1.0 had the highest betacyanin content. Betacyanin content decreased when stored under exposure of light compared to storage in dark. In this study, increasing concentration of NaCl decreased the absorbance values at faster rates for betacyanin-coated glass slides. Research limitations/implications Acetone is volatile and evaporates rapidly. Pigments extracted with acetone were stored in glass vials which were closed tightly to prevent evaporation. Social implications The social implication is the use of natural pigments from cactus species as a valuable and eco-friendly source in a coating system without adverse effects for human health. Originality/value The method for detection of stability and effectiveness of betacyanin pigment used as a natural colorant for coating application was beneficial and recent for environment-friendly and natural plant-based product development.