Total phenolic compounds and antioxidant capacity of baru almond and by-products evaluated under optimizing extraction conditions

The baru almond has a high nutrient and phytochemical density, such as monounsaturated fatty acids, dietary fiber, vitamin E, zinc, and phenolic compounds. This study aimed to optimize the extraction conditions of total phenolic compounds from baru almond (with and without skin) and baru almond skin using a fractional factorial 24-1 and the Box-Behnken designs, and to analyze the influence of the extraction factors on total phenolic content and antioxidant capacity (by ABTS, DPPH, and FRAP assays) in the extracts obtained. The optimal extraction conditions were: for whole baru almond (with skin) - 79% ethanol and 2 mg mL-1 solid-solvent ratio at 85 °C; for baru almond without skin - 68% ethanol and 20 mg mL-1 solid-solvent ratio during 34 min; and for baru almond skin - 40% ethanol and 0.2 mg mL-1 solid-solvent ratio at 66 °C. On these conditions, whole baru almond showed high phenolic content and antioxidant capacity, and the almond skin featured about 10% of phenolics and a very high antioxidant capacity. The experimental designs used revealed the baru almond skin as an abundant source of antioxidant compounds. We recommend the consumption of whole baru almond, and the use of its skin in different food systems.