Characterisation of fibre-rich ingredients obtained from defatted cold-pressed rapeseed cake after protein extraction

Fibre-rich ingredients obtained after protein isolate production from cold-pressed rapeseed meal using alkali extraction at pH 12 with ethanol pretreatment (ingredient 1), and natural deep eutectic solvent (NDES) extraction with choline chloride:urea (ChCl:urea) (ingredient 2) and betaine:citric acid (ingredient 3) were compared in terms of chemical profile, minerals, amino acids, antinutrients, and colour. All ingredients were rich in dietary fibres (46.9 f 2.36-63.0 f 1.44 %) and proteins (22.5 f 0.24-35.5 f 0.66 %). Minerals, particularly potassium, magnesium, zinc, manganese, and iron, were significantly present. The ChCl:urea system provided the highest lysine and methionine content, with methionine detected only in NDES-extracted ingredients. Glucosinolates were absent in all ingredients. Alkali extraction minimized total phenolic content and tannins, while betaine:citric acid extraction reduced phytates most effectively. NDES systems resulted in better colour parameters. Fibre-rich ingredients exhibit significant potential as functional components for enriching food products, combining high nutritional value with minimized antinutritional factors.