Comparison of isopropanol and hexane for extraction of vitamin E and oryzanols from stabilized rice bran

The effects of solvent-to-bran ratio (2∶1 and 3∶1, w/w), extraction temperature (40 and 60°C), and time (5, 10, 15, 20, and 30 min) were studied for hexane and isopropanol extraction. Increasing the solvent-to-bran ratios and extraction temperature increased the amounts of crude oil, vitamin E and oryzanol recovered for both solvents. An extraction time of 15 min was sufficient for optimum crude oil, vitamin E, and oryzanol extraction. Preheated isopropanol (3∶1 solvent/bran ratio and 60°C) extracted less crude oil (P<.05) but more vitamin E (P<.05) and similar amounts of oryzanol (P>.05) relative to preheated hexane. The data suggest that isopropanol is a promising alternative solvent to hexane for extraction of oil from stabilized rice bran.     

Degumming,Dewaxing and Deacidification of Rice Bran Oil-Hexane Miscella Using Ceramic Membrane: Pilot Plant Study

An indigenously developed low-cost clay-alumina-based ceramic microfiltration membrane of 19-channel configuration has been evaluated for degumming, dewaxing and deacidification of rice bran oil (RBO) miscella having different oil contents at pilot scale. Rice bran wax and soap particles in miscella will aggregate with changes in temperature. This suggests a technique for their effective separation. Low-temperature cross-flow membrane filtration was used for single-stage degumming-dewaxing and showed 70 % and 80 % removal of acetone insoluble residue from two RBO miscella samples, respectively. Color reduction was 50 %, and oryzanol retention was 70 %. NaOH was used for deacidification in a 10 % excess of that required based on the free fatty acid content in oil. This reduced free fatty acids to 0.2 %. Operating for 10 h with a 0.7 bar trans-membrane pressure, permeate fluxes of 15 and 8 L/m² hr were obtained for the degumming-dewaxing and deacidification operations, respectively. The process has advantages, such as high micronutrient content (1.56 % oryzanol) and negligible oil loss (2.6 %). Moreover, ceramic membrane processing of RBO miscella could be an effective pre-treatment step with respect to micronutrient enrichment, elimination of heating, neutral oil recovery and a viable option for solvent separation.     

Physical refining of rice bran oil in relation to degumming and dewaxing

Physical refining of rice bran oil (RBO) with acidity between 4.0 and 12.4% has been investigated in relation to degumming and dewaxing pretretments. It appears that physical refining after combined low-temperature (10°C) degumming-dewaxing produces good-quality RBO with respect to color, free fatty acid, oryzanol, and tocopherol content.     

Rapid equilibrium extraction of rice bran oil at ambient temperature

Rapid equilibrium extraction of soybean flour has been effective in obtaining an oil with reduced phospholipid content. This technique was examined to obtain a low phospholipid and low free fatty acid rice bran oil (RBO). The amount of RBO extracted with hexane from 1 g of rice bran at 22°C was measured over a 10-min period. The amount of oil extracted from variable amounts of bran with a fixed volume of solvent was also studied. Ninety percent of the oil was extracted in one minute, with 93% of the total RBO being extracted after ten minutes. This compares with the 98% yield obtained from soy flour, but increasing the amount of bran used did not reduce the extraction rate. This extraction method produced a good quality RBO with low phospholipid, low free fatty acid and low peroxide values.     

Effect of refining of crude rice bran oil on the retention of oryzanol in the refined oil

The effect of different processing steps of refining on retention or the availability of oryzanol in refined oil and the oryzanol composition of Indian paddy cultivars and commercial products of the rice bran oil (RBO) industry were investigated. Degumming and dewaxing of crude RBO removed only 1.1 and 5.9% of oryzanol while the alkali treatment removed 93.0 to 94.6% of oryzanol from the original crude oil. Irrespective of the strength of alkali (12 to 20° Be studied), retention of oryzanol in the refined RBO was only 5.4–17.2% for crude oil, 5.9–15.0% for degummed oil, and 7.0 to 9.7% for degummed and dewaxed oil. The oryzanol content of oil extracted from the bran of 18 Indian paddy cultivars ranged from 1.63 to 2.72%, which is the first report of its kind in the literature on oryzanol content. The oryzanol content ranged from 1.1 to 1.74% for physically refined RBO while for alkali-refined oil it was 0.19–0.20%. The oil subjected to physical refining (commercial sample) retained the original amount of oryzanol after refining (1.60 and 1.74%), whereas the chemically refined oil showed a considerably lower amount (0.19%). Thus, the oryzanol, which is lost during the chemical refining process, has been carried into the soapstock. The content of oryzanol of the commercial RBO, soapstock, acid oil, and deodorizer distillate were in the range: 1.7–2.1, 6.3–6.9, 3.3–7.4, and 0.79%, respectively. These results showed that the processing steps—viz., degumming (1.1%), dewaxing (5.9%), physical refining (0%), bleaching and deodorization of the oil—did not affect the content of oryzanol appreciably, while 83–95% of it was lost during alkali refining. The oryzanol composition of crude oil and soapstock as determined by high-performance liquid chromatography indicated 24-methylene cycloartanyl ferulate (30–38%) and campesteryl ferulate (24.4–26.9%) as the major ferulates. The results presented here are probably the first systematic report on oryzanol availability in differently processed RBO, soapstocks, acid oils, and for oils of Indian paddy cultivars.     

Structured lipids from rice bran oil and stearic acid using immobilized lipase from Rhizomucor miehei

The major objective of the present study was to prepare structured lipids rich in stearic acid from rice bran oil (RBO) using immobilized lipase (IM 60) from Rhizomucor miehei. The effects of incubation time and temperature, substrate molar ratio, and enzyme load on incorporation of stearic acid were studied. Acidolysis reactions were performed in hexane. Pancreatic lipase‐catalyzed sn‐2 positional analysis and tocopherol analyses were performed before and after enzymatic modification. The kinetics of the reaction was studied and maximum incorporation of stearic acid was observed at 6 h, at 37 °C, when the triacylglycerol and stearic acid molar ratio was maintained at 1 : 6 and the enzyme concentration was 10% of total substrates weight. Stearic acid in RBO after acidolysis was increased from 2.28 to 48.5%, with a simultaneous decrease in palmitic, oleic and linoleic acids. HPLC analysis of tocopherols and tocotrienols was carried out and their content in modified RBO was not significantly affected compared to that of native RBO. The oryzanol content of the modified RBO was reduced from 1.02 to 0.68%. Melting and crystallizing characteristics of the modified fat were studied using differential scanning calorimetry. The total solid fat content at 25 °C increased from 26.12 to 34.8% with an increase in stearic acid incorporation into RBO from 38 to 48%, but it was comparatively less than for cocoa butter and vanaspati. However, the modified RBO completely melted at 37 °C and was useful as plastic fat for various culinary purposes, bakery and confectionary applications. The results of the present study indicated that structured lipids prepared from RBO rich in stearic acid retained their beneficial nutraceuticals; in addition, they do not contain any trans fatty acids.     

Supercritical CO2 extraction of rice bran

Extraction of rice bran lipids with supercritical carbon dioxide (SC-CO₂) was performed. To investigate the pressure effect on extraction yield, two isobaric conditions, 7000 and 9000 psi, were selected. A Soxhlet extraction with hexane (modified AOCS method Aa 4–38; 4 h at 69°C) was also conducted and used as the comparison basis. Rice bran with a moisture content of 6%, 90% passable through a sieve with 0.297 mm opening, was used for extraction. A maximum rice bran oil (RBO) yield of 20.5%, which represents 99+% lipid recovery, was obtained with hexane. RBO yield with SC-CO₂ ranged between 19.2 and 20.4%. RBO yield increased with temperature at isobaric conditions. At the 80°C isotherm, an increase in RBO yield was obtained with an increase in pressure. The pressure effect may be attributed to the increase in SC-CO₂ density, which is closely related to the value of the Hildebrand solubility parameter. RBO extracted with SC-CO₂ had a far superior color quality when compared with hexane-extracted RBO. The level of sterols in SC-CO₂-extracted RBO increased with pressure and temperature.     

Oryzanol decreases cholesterol absorption and aortic fatty streaks in hamsters

Oryzanol is a class of nonsaponifiable lipids of rice bran oil (RBO). More specifically, oryzanol is a group of ferulic acid esters of triterpene alcohol and plant sterols. In experiment 1, the mechanisms of the cholesterol-lowering action of oryzanol were investigated in 32 hamsters made hypercholesterolemic by feeding chow-based diets containing 5% coconut oil and 0.1% cholesterol with or without 1% oryzanol for 7 wk. Relative to the control animals, oryzanol treatment resulted in a significant reduction in plasma total cholesterol (TC) (28%, P<0.01) and the sum of IDL-C, LDL-C, and VLDL-C (NON-HDL-C) (34%, P<0.01). In addition, the oryzanol-treated animals also exhibited a 25% reduction in percent cholesterol absorption vs. control animals. Endogenous cholesterol synthesis, as measured by the liver and intestinal HMG-CoA reductase activities, showed no difference between the two groups. To determine whether a lower dose of oryzanol was also efficacious and to measure aortic fatty streaks, 19 hamsters in experiment 2 were divided into two groups and fed for 10 wk chow-based diets containing 0.05% cholesterol and 10% coconut oil (w/w) (control) and the control diet plus 0.5% oryzanol (oryzanol). Relative to the control, oryzanol-treated hamsters had reduced plasma TC (44%, P<0.001), NON-HDL-C (57%, P<0.01), and triglyceride (TG) (46%, P<0.05) concentrations. Despite a 12% decrease in high density lipoprotein cholesterol (HDL-C) (P<0.01), the oryzanol-treated animals maintained a more optimum NON-HDL-C/HDL-C profile (1.1±0.4) than the contorl (2.5±1.4; P<0.0075). Aortic fatty streak formation, so defined by the degree of accumulation of Oil Red O-stained macrophage-derived foam cells, was reduced 67% (P<0.01) in the oryzanol-treated animals. From these studies, it is concluded that a constituent of the nonsaponifiable lipids of RBO, oryzanol, is at least partially responsible for the cholesterol-lowering action of RBO. In addition, the cholesterol-lowering action of oryzanol was associated with significant reductions in aortic fatty streak formation.     

Effect of high pressure pretreatment on drying kinetics and oleoresin extraction from ginger

The present study reports for the first time the effect of high pressure pretreatment (100–400?MPa, 10?min) on drying kinetics of ginger and its oleoresin extraction. High pressure pretreated samples were dried, powdered and solvent extracted. The increase in drying temperature (55–85°C) increased the moisture diffusivity (2.03–4.87?×?10^?9?m²/s) but resulted in decrease in 6-gingerol (53.98%) and oleoresin yield (57.31%). However, high pressure pretreatment followed by dehydration (55°C) resulted in higher moisture diffusivity (2.84–6.09?×?10^?9?m²/s) as well as enhanced extraction yield of 6-gingerol (34.05%) and oleoresin (28.29%).     

Preparation of diacylglycerol‐enriched palm olein by phospholipase A1‐catalyzed partial hydrolysis

Partial hydrolysis of palm olein catalyzed by phospholipase A₁ (Lecitase Ultra) in a solvent‐free system was carried out to produce diacylglycerol (DAG)‐enriched palm olein (DEPO). Four reaction parameters, namely, reaction time (2–10 h), water content (20–60 wt‐% of the oil mass), enzyme load (10–50 U/g of the oil mass), and reaction temperature (30–60 °C), were investigated. The optimal conditions for partial hydrolysis of palm olein catalyzed by Lecitase Ultra were obtained by an orthogonal experiment as follows: 45 °C reaction temperature, 44 wt‐% water content, 8 h reaction time, and an enzyme load of 34 U/g. The upper oil layer of the reaction mixture with an acid value of 54.26 ± 0.86 mg KOH/g was first molecularly distilled at 150 °C to yield a DEPO with 35.51 wt‐% of DAG. The DEPO was distilled again at 250 °C to obtain a DAG oil with 74.52 wt‐% of DAG. The composition of the acylglycerols of palm olein and the DEPO were analyzed and identified by high‐performance liquid chromatography (HPLC) and HPLC/electrospray ionization/mass spectrometry. The released fatty acids from the partial hydrolysis of palm olein catalyzed by phospholipase A₁ showed a higher saturated fatty acid content than that of the raw material.     

Determination of nonvolatile components in polar fractions of rice bran oils

High-oryzanol rice brain oil (HORBO), rice bran oil (RBO), and partially hydrogenated soybean oil (PHSBO) were used to prepare french fries. Polar fractions of the three oils were analyzed for nonvolatile components by high-performance size-exclusion chromatography (HPSEC) with ELSD. In all frying experiments, both HORBO and RBO yielded predominantly dimeric and monomeric materials. The concentrations of polymeric species in HORBO and RBO were greater than in PHSBO. The major degradation products from HORBO, RBO, and PHSBO were dimers (8.93 mg/100 mg oil), monomers (10.5 mg/100 mg oil), and DG (22.4 mg/100 mg oil), respectively. Thermal degradation via hydrolysis was much greater in PHSBO than in HORBO or RBO. Distribution data indicated that the extent of polymer formation from frying was in the order RBO>HORBO >PHSBO, consistent with the degree of lipid unsaturation and the oryzanol content in these oils. HPSEC-ELSD results from the two RBO showed that the amounts of various polymeric species, including trimers and higher polymers, were lower in HORBO than in RBO. The percentage of polar materials and the percentage of polymerized TG, which were used as indicators of oil quality and stability, decreased with increasing tocopherol and oryzanol contents in the order PHSBO>HORBO>RBO.     

The concentration of tocols from rice bran oil deodorizer distillate using solvent

Tocols (tocopherols + tocotrienols) have been concentrated efficiently from rice bran oil (RBO) deodorizer distillate using solvent at low temperature. The levels of total tocols, total tocopherols, and total tocotrienols in RBO deodorizer distillate (starting material) were 31.5, 14.9, and 16.6 mg/g, respectively. Nine different solvents were tested, and acetonitrile was selected as the optimal solvent for concentrating tocols from the RBO deodorizer distillate. There was a significant (p <0.05) increase in the tocol level of the liquid fractions with decreasing temperature, for incubation temperatures up to –20 °C. In addition, significant differences (p <0.05) were observed in the relative percentages of α‐tocopherol, γ‐tocopherol, α‐tocotrienol, and γ‐tocotrienol between the raw sample and liquid fractions obtained at different temperatures using acetonitrile as the solvent. The concentration of the tocols from the RBO deodorizer distillate was temperature dependent, and a maximum of 89.9 mg/g was attained in the liquid fraction at – 40 °C. The relative percentage of tocotrienol homologs in the liquid fraction obtained at – 40 °C was approximately 80%. With acetonitrile as the solvent, the optimal temperature for concentrating the tocols from RBO deodorizer distillate was –20 °C when yield was considered.     

Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures

Polyacrylamide‐grafted sodium alginate (PAAm‐g‐Na‐Alg) copolymeric membranes have been prepared, characterized, and used in the pervaporation separation of 10–80 mass % water‐containing tetrahydrofuran mixtures. Totally three membranes were prepared: (1) neat Na‐Alg with 10 mass % of polyethylene glycol (PEG) and 5 mass % of polyvinyl alcohol (PVA), (2) 46 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA, and (3) 93 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA. Using the transport data, important parameters like permeation flux, selectivity, pervaporation separation index, swelling index, and diffusion coefficient have been calculated at 30°C. Diffusion coefficients were also calculated from sorption gravimetric data of water–tetrahydrofuran mixtures using Fick's equation. Arrhenius activation parameters for the transport processes were calculated for 10 mass % of water in the feed mixture using flux and diffusion data obtained at 30, 35, and 40°C. The separation selectivity of the membranes ranged between 216 and 591. The highest permeation flux of 0.677 kg/m² h was observed for 93% grafted membrane at 80 mass % of water in the feed mixture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 272–281, 2002     

Processing Parameters on the Extraction of Olive Pomace Oil and Its Bioactive Compounds: A Kinetic and Thermodynamic Study

The effect of temperature (40–60 °C), solid/liquid ratio (1/4–1/12 g mL^?1), and agitation speed (AS) (100–800 rpm) on the extraction yield of olive pomace oil and on the recovery of its unsaponifiable matter (USM) during extraction were studied. Two kinetic models were tested to correlate the experimental data; the first proposed by So and Macdonald and the second by Sulaiman et al. The two models adequately describe the extraction process of both oil and USM. Higher extraction temperatures, solid to liquid ratios, and AS led to increased oil yield and favored USM in the extracted oil, and also increased the calculated mass transfer coefficients of the extraction. Changes in enthalpy and entropy were found to be positive while change in free energy was negative, indicating that the process was endothermic, irreversible, and spontaneous. Under equilibrium conditions, the oil yield was increased by a factor of approximately 1.096 and 1.054 for the model of So and Macdonald and Sulaiman et al., respectively, for every 10 °C rise in temperature.     

Extraction of Total Phenolics of Sour Cherry Pomace by High Pressure Solvent and Subcritical Fluid and Determination of the Antioxidant Activities of the Extracts

Abstract

High pressure liquid extraction (HPE) and subcritical fluid (CO₂+ethanol) extraction (SCE) were used for the extraction of total phenolic compounds (TPC) from sour cherry pomace. Antiradical efficiency (AE) of the extracts was also determined. Ethanol was the solvent for HPE and co‐solvent for SCE. Combinations of pressure (50, 125, 200 MPa), temperature (20, 40, 60°C), solid/solvent ratio (0.05, 0.15, 0.25 g/ml) and extraction time (10, 25, 40 min) were variables for HPE according to the Box‐Behnken experimental design. The variables used for SCE were pressure (20, 40, 60 MPa), temperature (40, 50, 60°C), ethanol concentration (14, 17, 20 wt%) and extraction time (10, 25, 40 min). For HPE, TPC, and AE at the optimum conditions (176–193 MPa, 60°C, 0.06–0.07 g solid/ml solvent, 25 min) were found as 3.80 mg gae/g sample and 22 mg DPPH^?/g sample, respectively. TPC and AE at the optimum conditions (54.8–59 MPa, 50.6–54.4°C, 20 wt% ethanol, 40 min) for SCE were determined as 0.60 mg gae/g sample and 2.30 mg DPPH^?/g sample for sour cherry pomace, respectively.     

Residual solvent and its diffusion in acrylic fibers

A survey showed that some commercial acrylic fiber products contain small quantities of residual solvent (dimethylacetamide). No diffusion of solvent from these products could be detected on laundering, dry cleaning, or exposure to synthetic perspiration. Acrylic carpets containing residual solvent were enclosed in sealed boxes to simulate a closed room. Air in the boxes was monitored for solvent content over a 14-day period at 24°C (75°F) and 38°C (100°F) at both low and high humidity conditions. In all cases the solvent content of the air was below the detection limit of the best analytical procedure available (below 0.1 ppm). Diffusion rates of sol vent from 15-denier carpel fiber into nitrogen were measured over the temperature range of 25–100°C. There was no detectable diffusion below 60°C measured over a 24-h period. Mass diffusivities ranged from 2.5 × 10^?19 cm²/s at 60°C to 6.4 × 10^?14 cm²/s at 100°C. Under the conditions of expected use, the rate of diffusion of residual solvent from acrylic fibers is very low. Based on the low concentrations of residual solvent and its very low diffusion rate, there is an extremely low probability of any exposure to solvent from the residual solvent present in commercial acrylic fiber products.     

Effects of the extraction conditions on the yield and composition of rice bran oil extracted with ethanol—A response surface approach

Rice bran oil was obtained from rice bran by solvent extraction using ethanol. The influence of process variables, solvent hydration (0-24% of water, on mass basis), temperature (60-90 °C), solvent-to-rice bran mass ratio (2.5:1 to 4.5:1) and stirrer speed (100-250 rpm) were analysed using the response surface methodology.The extraction yield was highly affected by the solvent water content, and it varied from 8.56 to 20.05 g of oil/100 g of fresh rice bran (or 42.7-99.9% of the total oil available) depending on the experimental conditions. It was observed that oryzanol and tocols behave in different ways during the extraction process. A larger amount of tocols is extracted from the solid matrix in relation to γ-oryzanol. It was possible to obtain values from 123 to 271 mg of tocols/kg of fresh rice bran and 1527 to 4164 mg of oryzanol/kg of fresh rice bran, indicating that it is feasible to obtain enriched oil when this renewable solvent is used. No differences in the chemical composition of the extracted oils were observed when compared to the data cited in the literature.     

Extraction of Radio-Strontium from Nitric Acid Medium Using Di-tert-Butyl Cyclohexano18-Crown-6 (DTBCH18C6) in Toluene–1-Octanol Diluent Mixture

An alternative extraction system to the SREX solvent using a diluent mixture comprising 4,4′(5′)di-tert-butylcyclohexano-18-crown-6 (DTBCH18C6) in 80% toluene–20% 1-octanol was developed and evaluated for Sr(II) extraction from pressurized heavy water reactor simulated high level waste (PHWR-SHLW). The acid uptake (5.7%) by the present solvent was significantly lower as compared to that by the SREX solvent (21%) which used 100% 1-octanol as the diluent. The extracted species conformed to the ion-pair [Sr(DTBCH18C6)(H₂O)_x]²⁺·2[(NO₃)(H₂O)_y]^?. Studies on Sr(II) extraction as a function of nitric acid concentration indicated more favorable extraction and stripping with the present solvent as compared to the SREX solvent. Loading studies with 0.025 M DTBCH18C6 in the diluent mixture, carried out using the Sr carrier, indicated a decrease in D_Sr from 3.1 with 10 ppm Sr carrier to 1.62 with 100 ppm Sr carrier. Other important physical parameters relevant for the extraction processes such as phase separation time (dispersion number), viscosity, and density were also measured. The radiation stability and reusability of the solvent was also investigated. In sharp contrast to the SREX solvent, with increasing absorbed dose the proposed solvent showed an increase in Sr extraction and an increased acid uptake.     

Purification and identification of rice bran oil fatty acid steryl and wax esters

Fatty acid steryl esters (FASE) and wax esters (WE) of rice bran oil (RBO) have potential applications in cosmetic, nutraceutical, and pharmaceutical formulations. FASE and WE were extracted from RBO by a modified Soxhlet extraction using hexane as the solvent. FASE and WE were then separated by storage in acetone at 10°C for 24 h. The FASE fraction was further purified by silica, gel column chromatography. The contents and compositions of FASE and WE, as well as their saponified products, were identified by GC and GC-MS. The identification of FASE and WE was carried out by comparing the retention time of GC peaks and mass spectral analysis with standards synthesized in our laboratory. FASE and WE accounted for ca. 4.0% of crude RBO, of which 2.8–3.2% and 1.2–1.4% are FASE and WE, respectively. GC-MS of FASE showed five major peaks. Major FA in the FASE fraction were linoleic acid and oleic acid, which were esterified with 4-desmethyl, 4-monomethyl, and 4,4-dimethyl sterols. The contents of 4-desmethylsterol, 4-monomethylsterol, and 4,4-dimethylsterol esters in crude RBO were 76.1, 8.7, and 15.1%, respectively. WE of RBO consisted of both even and odd carbon numbers ranging from C₄₄ to C₆₄. The major constituents were, saturated esters of C₂₂ and C₂₄ FA and C₂₄ to C₄₀ aliphatic alcohols, with C₂₄ and C₃₀ being the predominant FA and fatty alcohol, respectively. The advantages of using a modified Soxhlet extraction over column chromatography are less solvent usage and larger sample size per batch with shorter operation time.