Encapsulation of avocado oil with modified rice starch: thermal and functional properties and gastrointestinal release

Encapsulation is a well-established technology that provides thermal stability and enables controlled release of functional compounds, such as avocado oil (AO). In this study, AO was encapsulated through the spray-drying process at inlet (130 °C) and outlet (80 °C) temperatures using different ratios (2.5–12.5%) of enzymatically modified red rice starch (RRS) as the coating material, with α-amylase and amyloglucosidase. The results demonstrated that emulsions with higher concentrations of modified RRS (10% and 12.5%) exhibited higher zeta potential values (− 37.67 mV and − 38.01 mV), indicating greater stability. For all conditions, the process yield was above 49%, and encapsulation efficiency (EE) ranged from 70.51 to 91.36%. AO microcapsules (5.72–8.15 µm) also showed low water content (3.29–5.58%) and high solubility (66.18–81.55%), enhancing their applicability in various processes. Additionally, AO microcapsules produced with 10% modified RRS (RRS4) exhibited the highest levels of phenolic compounds (5.74 mg GAE/100 g) and antioxidant activity (0.29–0.61 µM Trolox/g). Significant variations (p < 0.05) in thermal properties resulting from different concentrations of modified RRS contributed to higher thermal stability of microcapsules, with greater mass loss (59.01–63.37%) in the temperature range of 160–400 °C. According to in vitro release studies, the microcapsules released AO in simulated salivary fluid, continuing in gastric and intestinal fluids. It is concluded that suitable concentrations of modified RRS (10%, RRS4) provided the best techno-functional properties and higher release rates during digestion simulation, offering promising perspectives for innovative solutions in the functional food industry.