Comparative study on amount of nutraceuticals in by-products from solvent and cold pressing methods of rice bran oil processing

Abstract

Rice bran oil (RBO) has become a popular oil globally. However, the RBO extraction process leaves various residue products, which contain bioactive substances of varying potency which could be significant sources of functional ingredients for both food production and pharmaceutical manufacture. The objective of our study was to compare the bioactive substances in various by-products derived from the two rice bran oil processing methods; solvent extraction and cold pressing. The residues from solvent extraction processing contained up to 97.37 mg/100 g of γ-aminobutyric acid in defatted rice bran, and the rice acid oil contained high levels of vitamin E (tocopherols, tocotrienols), up to 120.59 mg/100 g, as well as γ-oryzanol (3829.65 mg/100 g), phytosterol (599.40 mg/100 g), and policosanol compounds (332.79 mg/100 g). All of these values are higher than in the residues derived from cold pressing. Importantly, high amounts of total nutraceuticals (8.3 kg/100 kg) were found in residues from both processing methods, indicating the commercial potential of these residues as a source of functional ingredients for food production, as dietary supplements, and in pharmaceutical manufacture.

Keywords: By-products; Cold pressing process; Nutraceutical; Refining process; Rice bran oil.

Fig. 1

Flow chart of rice bran oil (RBO) production (a) RBO from solvent extraction process (b) RBO from cold pressed extraction process.

Fig. 2

LC-MS chromatograms of γ-oryzanol standard compounds (a) RAO γ-oryzanol extract (b). The numbers on the peaks (a) correspond to the cycloartenyl ferulate (1), 24-methylene cycloartenyl ferulate (2), campesteryl ferulate (3), β-sitosteryl ferulate (4).

Fig. 3

GC–MS chromatograms of phytosterol standard (a) FC phytosterol extract (b). The numbers on the peaks correspond to cholestane as internal standard (1), campesterol (2), stigmasterol (3), β-sitosterol (4) and sitostanol (5).

Fig. 4

Chromatogram for PCs standards (a) and HPW PCs extract (b). Docosanol (C22-OH) (1), Tetracosanol (C24-OH) (2), Hexacosanol (C26-OH) (3), Octacosanol (C28-OH) (4), Triacontanol (C30-OH) (5).