Optimal storage conditions for spray-dried chayote juice (Sechium edule (Jacq.) Sw. cv. Perla Negra) microencapsulated with gum arabic

Abstract

Sechium edule Perla Negra cultivar (CPN) chayote juice contains bioactive compounds beneficial for health, but it requires protection to maintain its biological activity during storage. In this study, CPN chayote juice was microencapsulated by spray drying using gum arabic (GA) as the wall material. The resulting microcapsules were evaluated through moisture adsorption isotherms at 25 °C, 35 °C, and 45 °C. A thermodynamic approach, based on the GAB, BET, GDW, and Condon models, was used to describe the adsorption characteristics within a water activity ($a_w$) range of 0.10–0.85. Additionally, microstructure, color, total flavonoid content (TFC), and cucurbitacins in the microcapsules were analyzed while stored at different $a_w$ levels at 35 °C. Two stability phases were identified: a high-stability phase (0.108 ⎼ 0.515 $a_w$) and a lower stability phase (0.515 ⎼ 0.821 $a_w$). Optimal storage conditions were determined based on monolayer moisture content (Mₒ), minimum integral entropy, and minimum change in spreading pressure (MCSP), with $a_w$ values from 0.116 to 0.450. These conditions correlated with minimal changes in microstructure, color, and bioactive compounds (TFC and cucurbitacins). The degradation rate constants for TFC followed first-order kinetics, with half-life times of 125 and 293 days for the first and second phases, respectively. This thermodynamic approach is a valuable tool for determining the optimal storage conditions and ensuring the preservation of the bioactive properties of CPN chayote juice, renowned for its antioxidant, anti-inflammatory, and anticancer activities, making it a promising ingredient for functional foods, dietary supplements, nutraceuticals, and phytopharmaceutical products.