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

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. [Display omitted] •Total nutraceuticals contents (6.6 kg/100 kg) found in by-products from solvent extraction and refining processes of rice bran oil production was higher than from cold pressed extraction process (1.7 kg/100 kg).•In Thailand, the total amount of bioactive substances including GABA, γ-oryzanol, phytosterol, vitamin E, and policosanols remained in defatted rice bran, the most abundant by-products discarded from rice bran oil manufacture, is estimated around 3200 tons per year.•Gamma-oryzanol was found to be predominant bioactive component in the by-products from both rice bran oil processes. By products including filter cake, acid oil, and wax contain are interesting source of nutraceuticals including oryzanol, phytosterol, policosanol compound.•The by-products from rice bran oil manufacture both with solvent and cold pressed production system have the potential to turn from low-value agro waste into high-value functional ingredients for food, cosmetics, and pharmaceutical manufacture.