Polifenóis da casca da jabuticaba (Plinia spp.) microencapsulados por spray drying e incorporados em bebida láctea: aspectos físico-químicos, estabilidade, bioacessibilidade e resposta glicêmica

Abstract

The jabuticaba peel (Plinia spp.) is a significant source of polyphenols, such as anthocyanins. However, it is commonly discarded as a byproduct, representing approximately 30% of the fruit. Due to its considerable content of these antioxidant phytochemicals, its utilization in the food industry could be a promising alternative, enhancing the nutritional aspects of products. In this context, the objective of this study was to microencapsulate jabuticaba peel extracts (EJB) using spray drying with maltodextrin (MD) and gum arabic (GA) as carrier agents. The microencapsulated powders, maltodextrin powder (PMD), and gum arabic powder (PGA), were characterized for moisture content, solubility, hygroscopicity, calorimetry, microstructure (SEM), thermal properties, crystallinity, phenolic and anthocyanin content, antioxidant capacity (ABTS, DPPH, and FRAP), and encapsulation efficiency (EE%). The powders (PMD and PGA) and the concentrated extract (EJB) were also incorporated into model dairy beverage systems, and their stability was evaluated during 28 days of storage in terms of pH, acidity, calorimetry, phenolic and anthocyanin content, and antioxidant capacity. The beverages were also subjected to in vitro gastrointestinal simulation (SGI) to assess their bioaccessibility, and their postprandial glycemic response was evaluated in healthy individuals. PMD had the lowest moisture content (4.22 ± 0.03). The hygroscopicity (18.08 ± 0.29 and 19.32 ± 1.16%) and solubility (92.71 ± 1.20 and 91.57 ± 0.69%) of PMD and PGA, respectively, were statistically similar (p>0.05). PMD had the highest a* color parameter value (54.20 ± 0.03), and PGA had the lowest ∆E values (2.87 ± 0.74), indicating that the original color of the pigments was preserved even after spray drying. PGA showed partially smooth surfaces, highlighting it as a good carrier agent, providing greater protection to the core material against potential degradation sources. The polyphenols exhibited higher thermal resistance (>200°C) and lower mass loss after microencapsulation compared to the extract without carrier agents. Both powders exhibited semicrystalline structures, indicating that the materials are potentially more resistant to storage. Regarding the chemical aspects, PGA had the highest total phenolic content (232.63 ± 9.04 mg GAE.100 g-1 ), while the total anthocyanin content was statistically similar (p>0.05) between PMD (53.85 ± 1.84 mg cy-3-glu.100 g-1 ) and PGA (50.20 ± 2.50 mg cy-3-glu.100 g-1 ). The highest ABTS (33.21 ± 1.68 μmol Trolox.g -1 ), DPPH (25.71 ± 0.25 μmol Trolox.g -1 ), and FRAP (86.69 ± 4.40 μmol ferrous sulfate/g-1 ) antioxidant capacities were obtained for PGA. The encapsulation efficiency for PMD was higher in terms of total phenolic content (82.64 ± 0.34%) and for total anthocyanin content, PMD (61.71 ± 0.81%) and PGA (64.39 ± 0.79%), with no significant difference (p>0.05). The dairy beverage with PGA had the lowest pH value (3.91 ± 0.02), and the highest acidity (1.33 ± 0.02). Both parameters remained stable throughout the storage period for all treatments. Regarding color, the beverage incorporated with PMD had the highest values of the a* parameter, but all treatments showed a significant reduction (p<0.05) during the 28 days of storage, mainly due to the degradation of anthocyanins, confirmed by the analysis of the kinetics and half-life of these compounds. The beverage incorporated with PGA had the longest half-life for anthocyanins (49.86 days), indicating that gum arabic promoted the greatest preservation of these pigments. The highest total phenolic content was obtained for the dairy beverages incorporated with PMD (105.33 ± 4.51 mg GAE.100 g-1 ), as well as the highest FRAP antioxidant activity (1661.68 ± 159.58 μmol ferrous sulfate/g-1 ). The dairy beverage incorporated with PGA had the highest ABTS antioxidant capacity (533.78 ± 144 μmol Trolox.100g-1 ). The DPPH antioxidant activity between the beverages incorporated with PMD and PGA was similar (p>0.05), being (2119.46 ± 344.09 and 2144.07 ± 963.70 μmol Trolox/100g-1 ), respectively. The total phenolic content and antioxidant potential remained stable for all treatments throughout the 28 days of storage. The in vitro gastrointestinal simulation (SGI) promoted a higher recovery of bioactives, possibly due to the breakage of the polyphenol-protein association by proteolytic enzymes, which may increase the bioavailability of polyphenols. The highest values of total phenolics after digestion were obtained for the beverages incorporated with PMD and EJB (283.47 ± 10.05 and 315.38 ± 7.61 mg GAE.100 g-1 ), respectively, considered statistically similar (p>0.05). The same applies to the values of total anthocyanins between the two treatments (31.72 ± 1.13 and 34.38 ± 0.10 mg cy-3-glu.100g-1 ). The lowest incremental glucose area under the curve (iAUC) was obtained for the beverages incorporated with PGA and EJB, reinforcing the importance of bioactives in reducing glycemia. In conclusion, both microencapsulated powders and the jabuticaba extract are good alternatives to increase the consumption of polyphenols in the diet, with considerable antioxidant potential, good stability, and a reduction in the glycemic response of food products, thus adding functionality to the incorporated product.