Corante natural de casca de pitaya: extração, encapsulação e aplicação em alimento

Abstract

Artificial food colorings are important technological aids used in a wide variety of sectors, providing color to mask undesirable qualities or even to draw attention to a product. However, research shows that the indiscriminate use of these colorings can cause health problems. The industry seeks ways to replace them with alternatives considered more natural and healthier. Therefore, plant extracts can be a viable means of obtaining natural colorings. Pitaya is a fruit with an attractive color, with a peel rich in pigments called betacyanins, and can be a promising source for obtaining a natural coloring. Thus, the objective of this study was to obtain an extract with the maximum concentration of betacyanin from the pitaya peel, transform it into a powder by spray drying, and apply it in a powder formulation for the preparation of gelatin. Two gelatin formulations were produced with the M10 and MG10 colorings and a control. They were stored under controlled temperature, humidity, and time conditions over a period of 60 days. The moisture content, pH, water activity, acidity, color, betacyanin content, and texture were evaluated. The optimization of betacyanin extraction from pitaya peel was performed using a Box-Behnken design where the variables were time, temperature, and solid-liquid ratio. To obtain the powder dyes by spray drying, maltodextrin was used in combination or not with gum arabic at concentrations of 10 and 20% solids, resulting in four formulations. The powder dyes were characterized in terms of moisture content, water activity, pH, acidity, solubility, hygroscopicity, apparent density, and evaluated for antioxidant capacity by the FRAP, ABTS, and DPPH methods, as well as phenolic compound and betacyanin content. The powdered dyes, regarding moisture and water activity, presented average values of 4% and 0.1, respectively, apparent density of 0.5, hygroscopicity of 15%, and solubility of 47% on average. For pH, the average was 5%, and acidity ranged from 0.1 to 0.3g./100g. For the antioxidant and phenolic compound analyses, the formulations with lower proportions of solids showed higher results. The phenolic compound content was 44, 32, 70, and 80 µg EAG for M10, M20, MG10, and MG20, respectively; these values were lower than those presented in other literature. The highest betacyanin concentration was 256 mg/100g for formulation M10. Microscopy and particle size analyses showed that the dye encapsulated only with maltodextrin presented smaller particles. During the storage of the three powder formulations for gelatin preparation, there were no changes in pH, acidity, moisture, or water activity. The betacyanin content decreased during storage; however, visually and in terms of color parameters, there was no variation. Gel strength analyses also showed that the addition of the dye to the two formulations did not cause significant changes when compared to the control. Thus, it can be considered that the gelatin formulations with the powdered dyes remained relatively stable and that the dye has the potential to color foods while maintaining its characteristics over time.