Stability of Phytochemical Compounds and Antioxidant Capacity of Garambullo (Myrtillocactus geometrizans) Extract Microencapsulated with Different Concentrations of Wall Material (Gum Arabic) During Storage and In Vitro Digestion

The garambullo fruit (Myrtillocactus geometrizans) is rich in phytochemical compounds; however, once these phytochemical compounds are extracted from the fruit, they are susceptible to degradation caused by environmental conditions, storage and the digestive process. The objective of the present study was to microencapsulate the ethanolic extract of garambullo fruit through spray drying using gum arabic (GA) at concentrations of 10%, 15% and 20%, and to determine its effect on the stability of phenolic compounds (PC), betacyanins (Bc), betaxanthins (Bx) and antioxidant capacity (ABTS; FRAP assays), during both storage and in vitro digestion. Storage at three temperatures (4 °C, 18 °C, and 30 °C) revealed that the degradation of phytochemical compounds and antioxidant capacity depends on both storage temperature and the concentration of the wall material. Through chemical kinetic analysis, it was determined that the degradation of phytochemical compounds and antioxidant capacity during storage followed first-order reaction kinetics. Microcapsules with 20% GA stored at 4 °C exhibited the longest half-life of phytochemical compounds and antioxidant capacity (PC: 3465 days; Bc: 1179 days; Bx: 1732 days; ABTS: 2590 days; and FRAP: 1821 days). After in vitro digestion, microcapsules with 20% GA exhibited the highest bioaccessibility of phytochemical compounds and antioxidant capacity (PC: 94.91%, Bc: 31.51%, Bx: 58.50%; ABTS: 89.17%, and FRAP: 88.46%), followed by microcapsules formulated with 15% GA (PC: 83.71%, Bc: 26.86%, Bx: 49.89%, ABTS: 74.31%, and FRAP: 80.64%), and finally microcapsules formulated with 10% GA (PC: 66.11%, Bc: 19.97%, Bx: 37.08%, ABTS: 63.45%, and FRAP: 52.57%). These results are intended to promote the use of garambullo fruit in the food industry for the formulation of functional foods or nutraceuticals, thereby enabling the exploitation of the benefits associated with the antioxidant compounds present in this fruit.