Nutritional and antioxidant profiling of Algerian rapeseed seeds (Brassica napus L.) and its cold-pressed by-products

Kheira Rebbah¹,Samira Meziani^1*,Abbassia Demmouche¹,Lahouaria Labga¹,Lallia Amara¹, Fatima Zohra Badri²,Ibtissem Ghaffari³,Fatima Zohra Chenni¹,Manel Nardjes Toumi⁴, Norredine Menadi¹

¹Djillali Liabes University Laboratory of Biotoxicology, Faculty of Natural Sciences and Life, BP 89 – 22000 Sidi Bel Abbes, Algeria
²Scientific and Technical Research Center in Physicochemical Analysis CRAPC, BP 384, 42004 Bou-Ismail, Algeria
³University of Dr. Moulay Tahar Saida, Laboratory of Biotoxicology, Pharmacognosy and biological valorization of plants, 20000 Saida, Algeria
⁴Djillali Liabes University of Sidi Bel-Abbes, LEDE Laboratory, 22000 Sidi Bel Abbes, Algeria

ARTICLE INFO	ABSTRACT
TYPE: Original scientific paper https://doi.org/10.17508/CJFST.2025.17.1.06 PDF	This study investigated the “Zitna” variety of rapeseed seeds (Brassica napus L.) cultivated in Algeria and their by-product cakes used for animal feed after cold extraction. Physicochemical parameters, mineral profile, phenolic compounds (extracted with acetone, methanol, ethanol, and water), and antioxidant activity by DPPH free radical scavenging were analysed. The methanolic extract of the Zitna variety were analysed using HPLC. The results showed minor differences in physicochemical composition. The protein content was 3.79 ± 0.01 mg/mL in the seeds and 4.92 ± 0.04 mg/mL in the cakes, reflecting an increased protein concentration in the by-products due to the extraction process. Mineral concentrations were determined using the flame atomic absorption spectroscopy (FAAS) technique, which revealed that cakes had higher levels of essential minerals than the seeds and the most abundant element was potassium (K) with a concentration (27.2 ± 0.8 mg/L). The highest total phenolic content (TPC) was observed in acetone extracts, with seeds having 67.7 ± 4.3 mg GAE/g and cakes 61.3 ± 1.1 mg GAE/g. Methanol extracts showed the highest total flavonoid content (TFC), with seeds containing 23.5 ± 0.6 mg QE/g and cakes 18.5 ± 0.6 mg QE/g. Antioxidant activity, measured by IC50 values, was higher in seeds compared to cakes, with acetone extracts having IC50 values of 6.5 mg/mL for seeds and 14.2 mg/mL for cakes. The negative correlations were detected between IC50 and phenolic contents in seeds (-0.98; -0.97) and cakes (-0.98; -0.990) respectively. The chromatogram of the ‘Zitna’ rapeseed extract showed that sinapic acid is the major compound, with antioxidant activity enhanced by the novel discovery of gossypin, a flavonoid with antioxidant and anti-inflammatory properties. These findings demonstrate that cold-pressed extraction of Algerian rapeseed seeds preserves and concentrates valuable nutritional and antioxidant properties in the by-products, making them suitable for various industrial applications.
*CORRESPONDENCE Samira Meziani meziani_samira@yahoo.fr
ARTICLE HISTORY Received: November 11, 2024 Accepted: January 20, 2025
CITATION Rebbah K, Meziani S, Demmouche A, Labga L, Amara L, Badri FZ, Ghaffari I, Chenni FZ, Toumi MN, Menadi N. Nutritional and antioxidant profiling of Algerian rapeseed seeds (Brassica napus L.) and its cold-pressed by-products. Croatian Journal of Food Science and Technology (2025) 17 (1) 81-100
COPYRIGHT: © 2024 by the author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).
	KEYWORDS antioxidant activity; cakes; correlations; minerals; polyphenolic content
	KEY CONTRIBUTION Cold extraction enriched rapeseed cakes with proteins and minerals, particularly potassium, optimizing their nutritional value for animal feed. Acetone and methanol allowed targeted extraction of phenolic and flavonoid compounds, enhancing antioxidant activity, particularly in seeds. Finally, the discovery of gossypin, an antioxidant flavonoid, enriches the functional profile of Algerian rapeseed.