Extraction and quantification of betalains in fourvarieties of dragon fruit for food coloring

Abstract

The main objective of this research study was to develop a procedure for extracting natural colorants, specifically betalains, from four varieties of dragon fruit (orejona, cebra, lisa, and rosa). Chromatographic and spectrophotometric techniques were employed for their characterization and quantification, aiming to obtain pigments suitable for various food products.The extraction process of the colorants involved several steps. Initially, an initial filtration was performed using a blanket-type sieve, followed by sonication for 30 minutes at a temperature below 30°C. Subsequently, the mixture was agitated for an hour, and a final filtration was conducted using the same blanket-type sieve. The obtained extracts underwent ultrafreezing and subsequent lyophilization to obtain the final product in powder form.Quantification of the betalains was carried out using UV-VIS spectrophotometry as an approximate method. The results for betacyanin quantification were as follows: orejona (0.05 mg/g), cebra (2.92 mg/g), lisa (3.88 mg/g), and rosa (6.02 mg/g), with rosa variety showing the highest content of betacyanins.In addition to quantification, complementary characterization analyses were performed using techniques such as thin-layer chromatography, HPLC (High Performance Liquid Chromatography), UV-VIS spectrophotometry, and FTIR (Fourier Transform Infrared Spectrsocopy).Furthermore, colorimetry analyses were conducted on yogurt and ice cream prepared with the obtained dragon fruit colorant. A sensory analysis was also carried out to evaluate the acceptance of the colorant in food applications.