Açaí seeds: An unexplored agro-industrial residue as a potential source of lipids, fibers, and antioxidant phenolic compounds

Açaí (Euterpe oleracea Mart.) is a popular native fruit found in the Amazon region which has high energy value and is rich in bioactive compounds. However, the processing steps to obtain açaí pulp generate a large volume of agro-industrial residues, mainly composed of seeds. In our study, we investigated the use of açaí seeds as a source of lipids, fibers, and phenolic compounds with antioxidant activity. The seeds showed a high content of dietary fibers (86 %) and a low lipid content (2.75 %), of which 49.24 % and 50.76 % corresponded to saturated and unsaturated fatty acids, respectively. An optimized açaí seed extract was obtained using 57 % ethanol at room temperature (25 °C). The extract showed strong in vitro antioxidant activity against DPPH (622.81 μmol/g) and ABTS (763.09 μmol TEAC/g) free radicals. Procyanidin B1 and B2, catechin, and epicatechin were identified in the extract and quantitated by HPLC-DAD. Despite its strong in vitro antioxidant activity, the açaí seed extract did not increase the oxidative stability of soybean oil submitted to accelerated oxidation tests. Yet unexplored, açaí seeds could be considered a potential raw material for the extraction of fibers and bioactive phytochemicals such as catechin, epicatechin, and procyanidins, for industrial applications other than as a natural antioxidant in bulk soybean oil.