This study proposed the separation of the phenolic compounds from the bracts by microwave‐assisted extraction at 700, 800, and 1,000 W power, in times of 10, 15, and 20 min using water as a solvent. The results showed that the power and time were significant on the yields of phenolic, tannin, and radical scavenging assay. The best extraction condition was obtained at 1,000 W for 20 min, with contents of 47.61, 27.09, and 779.95 mg/g, for total phenolic compounds, total tannins, and condensed tannins; and 427.28 and 467.79 μmol/g for radical scavenging capacity by ABTS·+ and DPPH·, respectively, and it did not present a significant difference with the exhaustive extraction using acetone as a solvent. The colorimetric parameters Hue angle and Chroma showed values of 62.28° and 31.20, respectively. The maximum predicted responses by response surface methodology were also reached at 1,000 W and 20 min. Practical applications Araucaria angustifolia bracts are a source of phenolic compounds, mainly condensed tannins, which are related to potential health benefits, such as antioxidant capacity and antimicrobial, antimutagenic and anticarcinogenic properties. The extract containing these molecules was obtained by microwave‐assisted extraction using water as a solvent, thus employing green separation technologies, which resulted in shorter residence times at high temperatures and lower losses of thermally sensitive components as well as energy consumption. The results obtained from the recovery of phenolic compounds in the extract demonstrated the feasibility of the method to be applied on the industrial scale for its use in food formulations.
The aqueous extract of Araucaria angustifolia bracts was obtained by microwave‐assisted extraction and encapsulated by spray‐drying and freeze‐drying using pectin/hydrolyzed collagen (PEC‐HC) and polydextrose/partially hydrolyzed guar gum (PD‐PHGG) dispersions, added to the extract in the proportions of 0.25:0.75:9 and 0.5:0.5:9 (wt/wt/wt), respectively. The powders encapsulated with the PD‐PHGG mixture by spray‐drying and freeze‐drying showed the highest retention rates for total phenolic compounds (80.57% and 89.94%) and solubility (98.00 and 97.69 g 100 g−1), respectively. The scanning electron microscopy (SEM) images presented spherical forms on the spray‐dried powders, while the freeze‐dried powders exhibited irregular forms. The results obtained by FTIR suggested that the encapsulation occurred in all samples by physical interactions, whereas the thermogravimetric analysis showed that the PEC‐HC powders demonstrated greater thermal stability. Accelerated storage tests indicated that the PD‐PHGG freeze‐dried powders had lower decrease in the antioxidant capacity. Practical applications The industrial use of Araucaria angustifolia bracts (sterile seeds) is currently considered a type of waste. However, the bracts present bioactive compounds, including condensed tannins, considered among phenolic compounds, the most important natural antioxidants. The phenolic compounds of the bracts were extracted by microwave, using exclusively water as a solvent. The application of green technologies is an interesting alternative for the food industry since the use of organic solvents is completely replaced, as well shorter exposure times to high temperatures are obtained and, consequently, lower energy expenditure and lower antioxidant capacity loss. For the encapsulation of phenolic compounds, dietary fibers and protein were used as wall materials, which resulted in a powder containing natural antioxidants, fibers, and essential amino acids, which can be applied in several food formulations.
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