Antioxidant potential of Juglans 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.

Food waste: a potential bioresource for extraction of nutraceuticals and bioactive compounds

“…It was observed that oil obtained by SC-CO 2 extraction had higher resistance against oxidation and higher radical scavenging activity compared to hexane extracted oil. Wenzel et al (2016) extracted phenolic compounds from black walnut (Juglans nigra) husks using SC-CO 2 with an ethanol modifier. The optimal extraction conditions were 68 °C and 20% ethanol in SC-CO 2 .…”

In‐situ extraction and impregnation of black walnut husk into polyethylene film using supercritical carbon dioxide with an ethanol modifier

“…In-situ extraction and impregnation of black walnut husk into polyethylene film using supercritical carbon dioxide with an ethanol modifier | 613 WENZEL Mikulic-Petkovsek, Slatnar, Veberic, Stampar, & Solar, 2011;Oliveira et al, 2008;Tabaraki & Rastgoo, 2014;Wang et al, 2015;Wenzel et al, 2016). Since walnut husks are commonly discarded, despite being a source of antioxidants, walnut husks present a potential for valorization.…”

“…At these conditions, extracts were shown to exhibit antioxidant potential of 0.0554 mmol trolox equivalent/g of walnut using the ferric reducing ability of plasma (FRAP) assay and 7.13 mg gallic acid equivalent/g of walnut using the total phenolic content (TPC) assay (Wenzel et al, 2016). For extraction and impregnation, the mass loading of walnut husk with respect to ethanol content was varied from 0 to 1 g of walnut husk per gram of ethanol.…”

“…The experimental conditions were chosen to match the center point of a factorial design of experiments of a previous study evaluating the effects of processing conditions upon antioxidant potential of walnut husk extract(Wenzel et al, 2016). The experimental conditions were chosen to match the center point of a factorial design of experiments of a previous study evaluating the effects of processing conditions upon antioxidant potential of walnut husk extract(Wenzel et al, 2016).…”

Antioxidant activity of Juglans regia L., Juglandaceae pericarp originated from Sumadija region

“…9,10 The pericarp of walnut fruit (green husk) shows antioxidant, antiproliferative and antimicrobial activity. 14, [16][17][18][19] Since there has not been data on the antioxidant activity of walnut husk from the species naturally distributed in Sumadija region of Serbia, the aim of this paper was to determine its phenol and tannin content, antioxidant activity and to compare it to the current information available on antioxidant activity of walnut parts from other regions.…”