Phytochemical Profile and Bioactivity of Industrial Rapeseed Meal Ethanol-Wash Solutes

• Published in: Waste and biomass valorization 2021-09, Vol.12 (9), p.5051-5063
• Main Authors: Georgiev, Radoslav, Ivanov, Ivan G., Ivanova, Petya, Tumbarski, Yulian, Kalaydzhiev, Hristo, Dincheva, Ivayla N., Badjakov, Ilian K., Chalova, Vesela I.
• Format: Article
• Language: English
• Subjects: Antifungal activity; Biological activity; Brassica napus; Carbohydrates; Dry weight; Engineering; Environment; Environmental Engineering/Biotechnology; Ethanol; Flavonoids; Food; Food industry; Food plants; Functional foods & nutraceuticals; Fungi; Fungicides; Human nutrition; Industrial Pollution Prevention; Ion currents; Iron; Melibiose; Nutrition; Original Paper; Phenolic acids; Phenols; Phytochemicals; Proteins; Rapeseed; Renewable and Green Energy; Scavenging; Sinapic acid; Solutes; Sucrose; Sugar; Waste Management/Waste Technology; Weight reduction
• ISSN: 1877-2641; 1877-265X
• DOI: 10.1007/s12649-021-01373-6

Rapeseed meal is a by-product of oil producing industry which contains a high amount of protein (37–42%). To prepare protein isolates, suitable for human nutrition, the industrial rapeseed meal is often subjected to a pre-treatment with aqueous ethanol solution. The aim of the study was to investigate the phytochemical profile and bioactivity of the ethanol-wash solutes (EWS) obtained as a waste product of the main process of the protein isolate preparation from industrial rapeseed meal. Proximate composition analysis revealed that total carbohydrates were more than half of the product (60.63%). The content of hydrolysable reducing sugars was 44.13%, while glucose was 7.22%. The total phenols amounted 13.38%. EWS contained 1.63% total flavonoids and 242.05 µmol/g dry weight glucosinolates. The major components, as determined by GC–MS analysis, were sucrose, turanose and melibiose with 22.68%, 4.08% and 3.97% of total ion current (TIC) of polar compounds, respectively; cetyl alcohol (2.45% of TIC) and methyl oleate (2.08% of TIC) representing nonpolar compounds, and sinapic acid (73.71% of TIC) which was the prevailing substance of the phenolic acids identified in the EWS. The 0.2% EWS, prepared in aqueous 70% ethanol solution, exhibited 70.68% scavenging capability of DPPH radicals and 585.11 µmol Fe 2+ /g EWS (dry weight) reducing capacity. The product demonstrated limited antibacterial but broad antifungal activity which was expressed against Aspergillus niger (ATCC 1015), Aspergillus flavus , Penicillium sp., Rhizopus sp. and Fusarium moniliforme (ATCC 38932) as determined by the agar-well diffusion assay. Overall, EWS exhibited bioactive capacity, which revealed its potential application as a value-added product in the food and nutraceutical industries or agriculture. The broad-spectrum antifungal activity makes the product a prospective agent for food biopreservation or plant bioprotection. Graphic Abstract