title: Antioxidant potential ofJuglans nigra,black walnut, husks extracted using supercritical carbon dioxide with an ethanol modifier.
abstract: The black walnut,Junglas nigra,is indigenous to eastern North America, and abscission of its fruit occurs around October. The fruit consists of a husk, a hard shell, and kernel. The husk is commonly discarded in processing, though it contains phenolic compounds that exhibit antioxidant and antimicrobial properties. For this study, black walnut husks were extracted using supercritical carbon dioxide with an ethanol modifier. The effects of temperature, ethanol concentration, and drying of walnut husks prior to extraction upon antioxidant potential were evaluated using a factorial design of experiments. The solvent density was held constant at 0.75 g/mL. The optimal extraction conditions were found to be 68°C and 20 wt-% ethanol in supercritical carbon dioxide. At these conditions, the antioxidant potential as measured by the ferric reducing ability of plasma (FRAP) assay was 0.027 mmol trolox equivalent/g (mmol TE/g) for dried walnut husk and 0.054 mmol TE/g for walnut husks that were not dried. Antioxidant potential was also evaluated using the total phenolic content (TPC) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assays and the FRAP assay was found to linearly correlate to the TPC assay.
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wenzel
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Storer Samaniego
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Lihua
authors.initials: L
authors.lastname: Wang
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Laron
authors.initials: L
authors.lastname: Burrows
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Evan
authors.initials: E
authors.lastname: Tucker
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Nathan
authors.initials: N
authors.lastname: Dwarshuis
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Michelle
authors.initials: M
authors.lastname: Ammerman
authors.affiliation: Kettering University 1700 University Ave Flint Michigan 48504.
authors.forename: Ali
authors.initials: A
authors.lastname: Zand
keywords: Antioxidant activity; DPPH; FRAP; TPC; black walnut husk; ethanol; supercritical carbon dioxide extraction