Rice Bran Oil: Extraction Technologies, Composition, and Applications – A Review


 Rice bran is an important source of nutrients that have many good bioactive compounds. This study examined the extraction of bran rice oil using supercritical carbon dioxide. Free fatty acids contained in bran rice were stabilized at 5.25% for 8 months by fluid bed dryer equipment. Supercritical carbon dioxide extraction of rice bran oil at pressure of 400 bar, temperature of 60 oC, CO2 flow rate of 20 g/min for 120 minutes yielded 14.84% oil. The concentration of γ-oryzanol in rice bran oil extracted by supercritical carbon dioxide (0.50%) was higher than in rice bran oil derived from hexane Soxhlet extraction (0.42%). The effect of pressure and temperature on extraction yield and the concentration of γ-oryzanol contained in rice bran oil was observed.
 Keywords
 Rice bran, rice bran oil, γ-oryzanol, free fatty acid, supercritical carbon dioxide.
 References
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Rice bran oil (RBO) is a valuable ingredient extracted from rice bran (RB), a side stream of polishing rice grain in the milling process. RBO is rich in bioactive ingredients with potential health benefits, such as gamma-oryzanol (GO) and gamma-aminobutyric acid (GABA). Despite its benefits, the quality of RBO depends on the degree of stabilisation of the RB, which is easily affected by lipase enzymes, and thus needs an effective treatment prior to RBO production. To assess the potential of the microwave-assisted method for RB stabilisation and RBO extraction, three Carolino rice varieties (Ariete, Teti, Luna) were tested. The effect of RB stabilisation was evaluated via acid value, water absorption, and GO and GABA levels. The RBO yield was optimised by solvent, temperature, and solvent-to-sample ratio, and the GO and fatty acid levels were determined. The RB stabilisation for the Luna variety did not affect the GO and GABA; for the Ariete and Teti varieties, the GO decreased by 34.4% and 24.2%, and the GABA increased by 26.5% and 47.0%, respectively. The GO levels in RBO samples were not affected by RB stabilisation. The RBO nutritional value was confirmed by the suitable ratio (>2) between polyunsaturated (PUFA) and saturated fatty acids (SFA), with the Teti variety presenting the highest ratio.

This report addresses the safety of cosmetic ingredients derived from rice, Oryza sativa. Oils, Fatty Acids, and Waxes: Rice Bran Oil functions in cosmetics as a conditioning agent--occlusive in 39 formulations across a wide range of product types. Rice Germ Oil is a skin-conditioning agent--occlusive in six formulations in only four product categories. Rice Bran Acid is described as a surfactant-cleansing agent, but was not in current use. Rice Bran Wax is a skin-conditioning agent--occlusive in eight formulations in five product categories. Industry did not directly report any use of Rice Bran Wax. Hydrogenated Rice Bran Wax is a binder, skin-conditioning agent--occlusive, and viscosity-increasing agent--nonaqueous in 11 formulations in six product categories. Rice Bran Oil had an oral LD50 of > 5 g/kg in white rats and Rice Wax had an oral LD50 of > 24 g/kg in male mice. A three-generation oral dosing study reported no toxic or teratologic effects in albino rats fed 10% Rice Bran Oil compared to a control group fed Peanut Oil. Undiluted Rice Bran Oil, Rice Germ Oil, and Hydrogenated Rice Bran Wax were not irritants in animal skin tests. Rice Bran Oil was not a sensitizer. Rice Bran Oil, Rice Germ Oil, Rice Wax, and Hydrogenated Rice Bran Wax were negative in ocular toxicity assays. A mixture of Rice Bran Oil and Rice Germ Oil had a ultraviolet (UV) absorption maximum at 315 nm, but was not phototoxic in a dermal exposure assay. Rice Bran Oil was negative in an Ames assay, and a component, gamma-oryzanol, was negative in bacterial and mammalian mutagenicity assays. Rice oils, fatty acids, and waxes were, at most, mildly irritating in clinical studies. Extracts: Rice Bran Extract is used in six formulations in four product categories. Rice Extract is a hair-conditioning agent, but was not in current use. Hydrolyzed Rice Extract is used in four formulations and current concentration of use data were provided for other uses. Hydrolyzed Rice Bran Extract, described as a skin-conditioning agent--miscellaneous, is used in two product categories. Use concentrations are in the 1% to 2% range. Rice Bran Extract is comprised of proteins, lipids, carbohydrates, mineral ash, and water. The content includes palmitic, stearic, oleic, and linoleic acids. Other components include antioxidants such as tocopherols. Rice Extract reduced the cytotoxicity of sodium chloride in male rats. Bran, Starch and Powder: Rice Bran (identified as rice hulls) is an abrasive and bulking agent in one formulation. Rice Starch is an absorbent and bulking agent in 51 formulations across a wide range of product categories. Rice Germ Powder is an abrasive and one manufacturer described an exfoliant use, but it was not reported to be used in 2002. Oral carcinogenicity studies done on components of Rice Bran (phytic acid and gamma-oryzanol) were negative. Rice Bran did not have an anticarcinogenic effect on 1,2-dimethylhydrazine-induced large bowel tumors. In cocarcinogenicity studies done using 1,2-dimethylhydrazine and other agents, with Rice Bran Oil and Rice Bran-derived hemicellulose and saccharide, tumor inhibition was observed; gamma-oryzanol did not inhibit the development of neoplasms. A decrease in cutaneous lesions in atopic dermatitis patients was reported following bathing with a Rice Bran preparation. Proteins: Hydrolyzed Rice Bran Protein and Hydrolyzed Rice Protein function as conditioning agents (hair or skin), but only the latter was reported to be used in a few products. An in vitro phototoxicity assay using UVA light found no photochemical toxicity. Rice bran protein hydrolysates are not acutely toxic, are not skin or ocular irritants in animals, are not skin sensitizers in guinea pig maximization tests, and are not irritating or sensitizing in clinical tests. Isolated cases of allergy to raw rice have been reported, but rice, in general, is considered non allergenic. The Cosmetic Ingredient Review (CIR) Expert Panel considered that safety test data available on certain of these ingredients could be extrapolated to the entire group. Although Rice Bran Extract does contain UV absorbing compounds at low concentrations, clinical experience suggested no phototoxicity would be associated with such materials. Rice derived ingredients generally are considered to be non allergenic. There were no safety test data available for Hydrolyzed Rice Extract and Hydrolyzed Rice Bran Extract, but their safety may be inferred from that of the extracts from which they are derived. Current levels of polychlorinated biphenyls (PCBs) and heavy metals in rice-derived ingredients used in cosmetics are not a safety concern. The Panel was concerned, however, that contaminants such as pesticides have been reported in Rice Bran Oil used for cooking. Pesticides and heavy metals should not exceed currently reported levels for rice-derived cosmetic ingredients. The CIR Expert Panel concluded that these rice-derived ingredients are safe as cosmetic ingredients in the practices of use and concentrations as described in this safety assessment.

Rice bran, a primary by-product from the rice processing industries, containing 10–15% oil, attracts significant attention from consumers due to its many health-promoting effects. The extraction methodology used is one of the most critical factors affecting the quality and yield of oil from rice bran. Using solvents is the current commercial process for rice bran oil extraction, which has its setbacks. It is challenging and expensive, and there is a risk of traces of solvent residue in the oil. Emerging combination extraction technologies offer zero to minimal solvent residues or chemical deformation while considering increasing environmental and energy footprint. Emerging combination processing technologies include new-age methods like supercritical fluid extraction, sub-critical fluid extraction, ultrasound-assisted enzymatic extraction, ohmic heating, and microwave-assisted extraction. These techniques have been reported to extract oil from rice bran, improving extraction efficiency and quality. These techniques demonstrate solid prospects for future applications. The present review discusses and compares these emerging technologies for oil extraction from rice bran commercially.

Conventional and ultrasound-assisted extraction of rice bran oil with isopropanol as solvent

The extraction of rice bran oil using the conventional organic solvent‐based Soxhlet method involves hazardous chemicals, whereas supercritical fluid extraction is a costly high‐temperature operating system. The subcritical carbon dioxide Soxhlet (SCDS) system, which operates at a low temperature, was evaluated for the extraction of rice bran oil in this study. In addition, rice bran that had been subjected to steam or hot‐air stabilization were compared with unstabilized rice bran (control). The yields; contents of tocopherols, tocotrienols and oryzanol; fatty acid profiles; and the oxidative stabilities of the extracted rice bran oils were analyzed. The yields using hexane and SCDS extraction were approximately 22 and 13–14.5 %, respectively. However, oil extracted using the SCDS system contained approximately 10 times more oryzanol and tocol compounds and had lower free fatty acid levels and peroxide values compared with hexane‐extracted oil. Overall, SCDS extraction of steamed rice bran represents a promising method to produce premium‐quality rice bran oil.

Rice bran oil is a type of oil with high nutritional value from rice bran. However, the free fatty acid content in it can increase by more than 60% with sufficient storage time. Free fatty acids contained in rice bran have the potential to be produced into biodiesel (methyl ester). This research aimed to determine the effect of methanol volume and esterification process time on biodiesel yield and to compare methyl ester yield to standard biodiesel. This research was conducted in two stages, namely rice bran oil extraction and esterification. In the extraction stage, rice bran was extracted with n-hexane for 3 hours at an operating temperature of 65oC. The esterification process was carried out by mixing rice bran oil, methanol with a certain volume (100, 125, 150, 175, 200 mL), and calcium carbonate catalyst as much as 1% of the amount of methanol. Esterification was carried out with time variations of 1; 1.5; 2; 2.5 and 3 hours. The results in the form of rice bran oil were analyzed for the value of the biodiesel yield. The result of rice bran oil was analyzed for initial free fatty acid value. Pure biodiesel product in the form of methyl ester was obtained through separation with glycerol as a by-product. The optimum methyl ester yield was 81.70% at 175 ml methanol volume for 3 hours. The methyl ester results are in accordance with SNI biodiesel for density and kinematic viscosity values.

Rice bran oil, not fiber, lowers cholesterol in humans 1–3

Rice bran oil extraction using alcoholic solvents: Physicochemical characterization of oil and protein fraction functionality

Cholesterol-Lowering in Hamsters Fed Rice Bran at Various Levels, Defatted Rice Bran and Rice Bran Oil ,

This research aimed to study the effect of solvents, namely n-hexane and ethanol, on the yield of crude rice bran oil extraction. The effects of extraction temperatures of 50, 60, and 70 ºC and extraction times of 1, 3, 6, 12, and 24 h were investigated. Rice bran composition was determined. It was found that protein, lipid, moisture, fiber, ash, and carbohydrate content were 12.65±0.56, 16.32±0.81, 7.65±0.62, 10.25±0.64, 6.38±0.59, and 46.75 %, respectively. From the results, the rice bran oil yield from n-hexane extraction was significantly higher than ethanol extraction, with p < 0.05. The maximum rice bran oil obtained from n-hexane extraction was 16.23±0.34 %. The highest yield of rice bran oil was obtained from extraction temperature of 60 - 70 ºC for 12 - 24 h. After extraction by the optimum conditions at 60 ºC for 12 h, the rice bran oil was kept for 1, 2, 3, 4, and 8 weeks for investigation of its quality changes. It can be concluded that the optimum conditions for rice bran oil extraction was with using n-hexane as a solvent for extraction at a temperature of 60 ºC for 12 h. Storing oil for 0, 1, 2, 4, and 8 weeks resulted in the increase of free fatty acids (FFA) and peroxide value, whereas iodine value and saponification value were relatively constant. HIGHLIGHTS n-Hexane and ethanol effect the yield of crude rice bran oil extraction The rice bran oil yield from n-hexane extraction was higher than ethanol extraction The optimum conditions for rice bran oil extraction were with using n-hexane as a solvent for extraction at a temperature of 60 ºC for 12 h Storing rice bran oil for 8 weeks resulted in the increase of free fatty acids (FFA) and peroxide value, whereas iodine value and saponification value were relatively constant

Background: Alkaloids are bioactive nitrogenous compounds with significant pharmacological applications, including analgesic, anti-inflammatory, anticancer, neuroprotective, and antimicrobial effects. Conventional extraction methods rely on toxic organic solvents, leading to environmental concerns and inefficiencies in yield and purity. The adoption of green extraction technologies, such as Supercritical Fluid Extraction (SFE), Microwave-Assisted Extraction (MAE), and Ultrasound-Assisted Extraction (UAE), offers a sustainable and efficient alternative. These methods enhance extraction efficiency, reduce processing time, and minimize solvent toxicity, ensuring safer and more effective therapeutic applications. Objective: This study aimed to evaluate and compare the efficiency of SFE, MAE, and UAE in the extraction, isolation, and purification of alkaloids from Papaver somniferous and Erythroxylon coca. The focus was on optimizing extraction conditions to maximize yield, purity, and recovery while minimizing environmental impact. Methods: Plant materials were sourced from authenticated suppliers, processed into fine powder, and stored under controlled conditions. SFE, MAE, and UAE were performed under optimized conditions, with SFE utilizing CO₂ as a supercritical solvent at 40°C and 2500 psi with a 12 g/min flow rate. The extracted alkaloids were quantified using UV-Vis spectrophotometry and high-performance liquid chromatography (HPLC) with an Agilent C18 reverse-phase column and a mobile phase of acetonitrile-water (50:50) at a flow rate of 1.0 mL/min. Statistical analysis, including one-way ANOVA and Tukey’s HSD post hoc test, was conducted to determine significant differences in extraction performance (p < 0.05). Recovery rates, purity levels, and solvent consumption were also assessed for each method. Results: SFE yielded the highest alkaloid concentrations, with P. somniferous producing 25.7 mg/g of morphine and 18.3 mg/g of codeine, outperforming MAE (22.4 mg/g and 15.2 mg/g) and UAE (19.5 mg/g and 13.1 mg/g). E. coca yielded 30.4 mg/g of cocaine via SFE, significantly higher than MAE (26.8 mg/g) and UAE (23.5 mg/g). HPLC purity analysis showed SFE resulted in 97% purity for morphine, 91% for codeine, and 98% for cocaine, surpassing MAE (91%, 87%, and 93%) and UAE (87%, 83%, and 89%). Recovery rates were highest for SFE (96.8% for P. somniferous, 95.6% for E. coca), exceeding those of MAE (93.4%, 91.8%) and UAE (90.1%, 88.2%). Solvent consumption was lowest for SFE, requiring only 15 mL per gram of alkaloid, compared to MAE (27 mL) and UAE (34 mL). The coefficient of variation (CV) was lowest for SFE (4.1%), demonstrating superior precision over MAE (5.7%) and UAE (7.2%). Conclusion: This study confirms that SFE is the most effective, precise, and environmentally sustainable technique for alkaloid extraction, yielding the highest purity and recovery rates while minimizing solvent waste and environmental impact. The findings support the adoption of green extraction methodologies for large-scale pharmaceutical applications, ensuring safer and more efficient production of high-purity alkaloids for therapeutic use.

Globally, 50% of people consume rice (Oryza sativa), which is among the most abundant and extensively ingested cereal grains. Rice bran is a by-product of the cereal industry and is also considered a beneficial waste product of the rice processing industry. Rice bran oil (RBO) is created from rice bran (20-25 wt% in rice bran), which is the outermost layer of the rice kernel; has a lipid content of up to 25%; and is a considerable source of a plethora of bioactive components. The main components of RBO include high levels of fiber and phytochemicals, including vitamins, oryzanols, fatty acids, and phenolic compounds, which are beneficial to human health and well-being. This article summarizes the stabilization and extraction processes of rice bran oil from rice bran using different techniques (including solvent extraction, microwaving, ohmic heating, supercritical fluid extraction, and ultrasonication). Some studies have elaborated the various biological activities linked with RBO, such as antioxidant, anti-platelet, analgesic, anti-inflammatory, anti-thrombotic, anti-mutagenic, aphrodisiac, anti-depressant, anti-emetic, fibrinolytic, and cytotoxic activities. Due to the broad spectrum of biological activities and economic benefits of RBO, the current review article focuses on the extraction process of RBO, its bioactive components, and the potential health benefits of RBO. Furthermore, the limitations of existing studies are highlighted, and suggestions are provided for future applications of RBO as a functional food ingredient.

The utilization of waste cooking oil from rice bran and fish byproducts including their wastes can contribute to mitigate the environmental burden like global warming what already being faced by our society. Converting waste oils /fat bearing materials to biodiesel fuel for recycling and reusing material, and reducing Co2 emission equivalent to the amount that is produced when petroleum derived diesel fuel is used. Waste cooking oil ( rice bran oil) and fish oil have emerged as the most promising sources for biodiesel production. This study was investigated to understand the proper transesterification, amount of biodiesel production (ester) and physical properties of biodiesel. Biodiesel production was higher in rice bran waste oil than in fish byproducts oil. However, crude glycerine was lower in rice bran oil than in fish oil. There was a difference in biodiesel production in different concentrations of methanol and catalyst used in rice bran and fish oil from byproducts. These results indicate that high quality biodiesel can be produced from waste rice bran and fish byproducts oil as environmental recycling process.

Rice Bran Oil Extraction in Sri Lanka: Data for Process Equipment Design