Stability Improvement of Betalains Recovered from Red Dragon Fruit Peels (Hylocereus polyrhizus) by Cellulose-Based Encapsulation

This study promoted a valorization pathway of Red Dragon Fruit Peel, including extraction of betalains and pectin, stabilization of batalains and expanding the application of betalains and pectin in jam and jellies. Betalains were extracted by the same weight of ethanol 96% at 45 ºC for 1 h and obtained with the content of 2.09 ± 0.03 mg/g of dry peels. To minimize the solid wastes, the alcohol-insoluble residues of betalains extraction were utilized to extract pectin by citric acid 0.1 M at 85 °C for 120 min with 19.8% yield and 56.8% DE (degree of esterification). Betalains stabilization focused on the encapsulation in support of the freeze-drying technique and microcrystalline cellulose (MCC) as a wall material. Freeze-dried MCC/betalains complexes were prepared by different weight ratios of betalains and MCC (1:3, 1:5, and 1:10). Encapsulation of betalains promoted significantly higher stability at different storage conditions: cold (4 °C) and room temperature (27 °C) with daylight and without daylight. The stability of encapsulated betalains was improved at high temperatures (80 °C and 100 °C), various pH levels (1.2, 3.6, 5.6, and 7.4) and water activities (0.089 and 0.898) when compared with the nonencapsulated betalains. The incorporation of encapsulated betalains into pineapple jam and gummy candy demonstrated storage stability after a two-week storage period.