Garambullo fruit (Myrtillocactus geometrizans) is a rich source of phytochemical compounds that exhibit antioxidant, anti-hyperglycemic, and anti-inflammatory activities, helping to prevent diseases associated with oxidative stress. The objective of this study was to evaluate phenolic compound (PC), betalain (BL), betaxanthin (BX), and betacyanin (BC) contents, and in vitro biological activities (antioxidant, anti-hyperglycemic, and anti-inflammatory) in microencapsulated garambullo extract during in vitro gastrointestinal digestion and storage. Microencapsulation was performed using spray drying. Arabic Gum (GA, 10% in feed solution) and soy protein isolate (SPI, 7% in feed solution) were used as wall materials. After in vitro digestion, the microcapsules (GA, SPI) exhibited higher bioaccessibility (p ≤ 0.05) of PC, BL, BX, and BC, and higher antioxidant activity (AA), compared to the non-encapsulated extract. Both microcapsules showed bioaccessibility in anti-hyperglycemic activity: α-amylase (GA: 90.58%, SPI: 84.73%), α-glucosidase (GA: 76.93%, SPI: 68.17%), and Dipeptidyl peptidase-4 (DPP-4) (GA: 52.81%, SPI: 53.03%); and in anti-inflammatory activity: cyclooxygenase-1 (COX-1) (GA: 78.14%, SPI: 77.90%) and cyclooxygenase-2 (COX-2) (GA: 82.77%, SPI: 84.99%). During storage, both microcapsules showed a similar trend with a significant decrease (p ≤ 0.05) in PC (GA: 39.29%, SPI: 39.34%), BL (GA: 21.17%, SPI: 21.62%), BX (GA: 23.89%, SPI: 23.45%), BC (GA: 19.55%, SPI: 19.84%), and AA (GA: 41.59%, SPI: 42.51%) after 60 days at 30 °C. Both microcapsules retained anti-hyperglycemic activity evaluated by the inhibitory activity of α-amylase (GA: 68.84%, SPI: 70.18%), α-glucosidase (GA: 59.93%, SPI: 58.69%), and DPP-4 (GA: 52.81%, SPI: 53.01%), and anti-inflammatory activity evaluated by the inhibitory activity of COX-1 (GA: 82.18%, SPI: 82.81%) and COX-2 (GA: 81.11%, SPI: 81.08%). Microencapsulation protected the phytochemical compounds and in vitro biological activities by allowing controlled release during in vitro digestion compared to the non-encapsulated extract. However, after 60 days storage at 30 °C, 60% of PC and AA, 80% of BL, BX, and BC, and 20–45% of the anti-hyperglycemic and anti-inflammatory activity were lost.
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