Microcápsulas de óleo de pequi obtidas por coacervação complexa e reticuladas com ácido tânico: digestibilidade e aplicação em alimento funcional

Abstract

Cerrado, Brazil's second-largest biome, is home to a diverse range of plant species that produce fruits with very distinctive sensory characteristics and high nutritional value. Among these species, pequi (Caryocar brasiliense Cambess.) stands out. The oil extracted from its pulp exhibits antioxidant and anti-inflammatory activity, properties mainly attributed to carotenoids. However, these compounds are prone to degradation when exposed to high temperatures, humidity, and oxygen. In this context, microencapsulation through complex coacervation emerges as a promising strategy to enhance the stability of bioactive compounds. Microcapsules obtained via this technique are generally unstable in high salt concentrations, and under pH and temperature variations. Therefore, the incorporation of cross-linking agents, such as tannic acid, can improve the stability of the wall material. In this sense, the present study aimed to evaluate the influence of tannic acid as a cross-linking agent on the characterization, stability, and in vitro digestibility of microcapsules containing pequi pulp oil, using gelatin and gum arabic as wall materials, as well as its application in a food product. To obtain the microcapsules, 7.5 g of pequi oil was used, with a homogenization speed of 15,000 rpm at a temperature of 50°C. Tannic acid was incorporated at concentrations of 0.1, 0.25, and 0.5%. The addition of tannic acid did not significantly affect yield (90.11 to 90.67%), encapsulation efficiency (83.01 to 85.94%), or oil retention (82.11 to 91.76%). Thermogravimetric analysis (TGA) showed that the interaction between the encapsulating agents was efficient, which delayed oil degradation. The 0.5% tannic acid concentration improved the induction period in accelerated oxidation analysis in Rancimat, in addition to increasing antioxidant activity and β-carotene stability. In in vitro digestibility test, greater β-carotene release (87.67%) was observed in the intestinal phase. Microcapsules containing 0.5% tannic acid were applied in yogurt and subjected to spray drying, using whey protein isolate (WPI) and maltodextrin (MD) as carrier agents, following a full factorial design. From this design, two formulations were selected: one with 20 g of WPI, 5 g of MD, and 30 g of mango pulp, and another with the same concentration of carrier agents but without the fruit. The products showed high β-carotene content (115.86 and 263.29 µg/g), as well as retention (45.89 and 78.99%), high protein content (43.98 and 53.81 g/100 g), low moisture (2.49 and 3.10 g/100 g), water activity (0.254 and 0.269), hygroscopicity (13.09 and 14.89%), high solubility (83.43 and 85.32%), and β-carotene stability. However, the product showed acidity (0.34 and 0.39 g lactic acid/100 g) below the level required by Brazilian legislation for a product to be classified as yogurt; therefore, the correct designation would be powdered dairy compound. Sensory analysis indicated that the formulation with mango pulp added had higher acceptability in almost all attributes, as well as a more favorable purchase intention. It was concluded that complex coacervation microencapsulation with added tannic acid is an effective approach for protecting pequi oil. Furthermore, its application in powdered functional food demonstrated favorable characteristics, highlighting the effectiveness of spray drying.