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Article

Recovery of Bioactive Compounds from Hazelnuts and Walnuts Shells: Quantitative–Qualitative Analysis and Chromatographic Purification

1
Chemical and Environmental Engineering Department, University of the Basque Country (UPV/EHU), Plaza Europa 1, 20018 San Sebastián, Spain
2
InnoRenew CoE, Livade 6, 6310 Izola, Slovenia
3
Chemistry and Chemical Engineering Department, Åbo Akademi University, Process Chemistry Centre, Porthansgatan 3, FI-20500 Åbo, Finland
*
Author to whom correspondence should be addressed.
Biomolecules 2020, 10(10), 1363; https://doi.org/10.3390/biom10101363
Received: 19 August 2020 / Revised: 20 September 2020 / Accepted: 22 September 2020 / Published: 24 September 2020
(This article belongs to the Special Issue Biomolecules from Plant Residues)
Hazelnut (HS) and walnut (WS) shells, an abundant by-product of the processing industries of these edible nuts, are traditionally considered as a low-value waste. However, they are a source of valuable compounds with an interesting chemical profile for the chemical and pharmaceutical sectors. In this study, the lipophilic and hydrophilic extracts present in HS and WS were quantified and identified, then the polar fractions were chromatographically separated, and their antioxidant capacity was studied. The experimental work includes the isolation of crude lipophilic and hydrophilic extracts by an accelerated extraction process, chromatographic analysis (gas chromatography-flame ionization (GC-FID), GC-mass spectroscopy (GC-MS), high-performance size-exclusion chromatography (HPSEC), thin-layer chromatography (TLC)), and quantification of the components. In addition, a thorough compositional characterization of the subgroups obtained by flash chromatography and their antioxidant capacity was carried out. The gravimetric concentrations showed different lipophilic/hydrophilic ratios (0.70 for HS and 0.23 for WS), indicating a higher proportion of polar compounds in WS than in HS. Moreover, the lipophilic extracts were principally composed of short-chain fatty acids (stearic, palmitic, and oleic acid), triglycerides, and sterols. The polar fractions were screened by thin-layer chromatography and then separated by flash chromatography, obtaining fractions free of fatty acids and sugar derivatives (97:3 in HS and 95:5 in WS), and mixtures richer in phenolic compounds and flavonoids such as guaiacyl derivatives, quercetin, pinobanksin, and catechin. The most polar fractions presented a higher antioxidant capacity than that of the crude extracts. View Full-Text
Keywords: nutshells; biowaste valorization; accelerated extraction; chromatographic analysis; fractionation; phenolic compounds; antioxidant capacity nutshells; biowaste valorization; accelerated extraction; chromatographic analysis; fractionation; phenolic compounds; antioxidant capacity
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MDPI and ACS Style

Herrera, R.; Hemming, J.; Smeds, A.; Gordobil, O.; Willför, S.; Labidi, J. Recovery of Bioactive Compounds from Hazelnuts and Walnuts Shells: Quantitative–Qualitative Analysis and Chromatographic Purification. Biomolecules 2020, 10, 1363. https://doi.org/10.3390/biom10101363

AMA Style

Herrera R, Hemming J, Smeds A, Gordobil O, Willför S, Labidi J. Recovery of Bioactive Compounds from Hazelnuts and Walnuts Shells: Quantitative–Qualitative Analysis and Chromatographic Purification. Biomolecules. 2020; 10(10):1363. https://doi.org/10.3390/biom10101363

Chicago/Turabian Style

Herrera, René, Jarl Hemming, Annika Smeds, Oihana Gordobil, Stefan Willför, and Jalel Labidi. 2020. "Recovery of Bioactive Compounds from Hazelnuts and Walnuts Shells: Quantitative–Qualitative Analysis and Chromatographic Purification" Biomolecules 10, no. 10: 1363. https://doi.org/10.3390/biom10101363

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