Optimized extraction of polyphenolic antioxidant compounds from Brazil nut (Bertholletia excelsa) cake and evaluation of the polyphenol profile by HPLC

BACKGROUND: The solid residue (cake) of pressed Brazil nut oil has high energy value and contains high levels of nutrients and bioactive compounds, such as polyphenols. However, little is known about these components in this by-product. Extraction is the first step in investigating the phenolic compounds in Brazil nut cake because extraction conditions might impact the yields of phenolic compounds and antioxidant capacity. The aim of this study was to select the best phenolic compound extraction conditions for Brazil nut cake by using factorial experimental design and to characterize the phenolic compounds in the extract. RESULTS: The optimal extraction of antioxidant phenolic compounds from Brazil nut cake was achieved under the following conditions: ethanol-water (40: 60; v/v); 2.5 min homogenization; and 1 h extraction at 60 degrees C. The phenolic compound profile of the Brazil nut cake extract using the optimized extraction was determined by high-performance liquid chromatography with photodiode array detection. Six phenolic acids (gallic acid, protocatechuic acid, 2,4-dihydroxybenzoic acid, p-hydroxybenzoic acid, p-coumaric acid and sinapic acid) and one flavonoid ((+)-catechin) were identified, and the contents of the phenolic compounds varied from 70.0 to 421 mg kg(-1). CONCLUSION: Knowledge of the potential bioactivity of Brazil nut cake identified in the present study might promote its use in the food industry. (c) 2015 Society of Chemical Industry