On-line extraction-reaction of canola oil using immobilized lipase in supercritical CO2

Lipase-catalyzed hydrolysis of canola oil in supercritical CO₂ (SCCO₂) was studied as a model reaction to develop an on-line extraction–reaction process to extract oil from oilseeds and convert the oil to other valuable products using SCCO₂. Immobilized lipase from Mucor miehei was used as the catalyst and the process was carried out at 24 MPa and 35°C. Product composition was analyzed using supercritical fluid chromatography. The effect of enzyme load, CO₂ flow rate and canola flake load on the amount of product and its composition was investigated. Hydrolysis occurred to a larger extent to free fatty acids and glycerol with an increase in enzyme load, a decrease in CO₂ flow rate or a decrease in canola load. On-line extraction-reaction process using SCCO₂ shows great potential for new process design to obtain products from agricultural commodities for use as ingredients in food and other industries.     

Production of structured lipids by lipase-catalyzed acidolysis in supercritical carbon dioxide: Effect on acyl migration

Structured lipids were synthesized by the acidolysis of corn oil by caprylic acid in supercritical carbon dioxide (SCCO₂) with Lipozyme RM IM from Rhizomucor miehei. The effects of pressure and temperature on the reaction were studied. To compare the degrees of acyl migration in the SCCO₂ and solvent-free reaction systems, the effects of reaction time on the degree of acyl migration were also studied. The highest mole percentage incorporation of caprylic acid (62.2 mol%) occurred at 24.13 MPa in SCCO₂. The overall incorporation of caprylic acid in the SCCO₂ system remained higher than that in the solvent-free system at every temperature tested. This trend was observed more clearly at lower temperatures (35–55°C) than at higher temperatures (65–75°C). Acyl migration with both reaction systems was low, with a negligible difference between them up to 12 h, after which the degree of acyl migration in the solvent-free system increased rapidly with time up to 24 h compared with the SCCO₂ system.     

Column Fractionation of Canola Oil Deodorizer Distillate Using Supercritical Carbon Dioxide

Semi-continuous column fractionation of canola oil deodorizer distillate using supercritical CO₂ (SCCO₂) was carried out to determine the feasibility of value-added processing of this feed material for the recovery of bioactive components such as sterols and tocopherols and to determine the effect of operating conditions [pressure (20, 25 MPa using a temperature gradient of 70–100 °C), temperature (70, 100 °C) and a linear temperature gradient (70–100 °C at 25 MPa)] on extract yield and separation efficiency. Total extract yield increased significantly (p ≤ 0.05) with pressure, whereas at isobaric conditions (25 MPa) the highest yield was obtained at the lowest temperature tested (70 °C). Fractionation efficiency was reflected in the composition of fractions and was affected by operating conditions. Residue composition was determined by extract yield in addition to selectivity. Use of the thermal gradient (70–100 °C) decreased the content of volatiles, free fatty acids and tocopherols while increasing sterol content significantly (p ≤ 0.05) to a level of 40% (GC area %) in the residue obtained at 25 MPa. The findings indicate the potential of canola oil deodorizer distillate as a source of sterols and warrant further research on the countercurrent column fractionation to improve the separation efficiency.     

Conversion of oils to monoglycerides by glycerolysis in supercritical carbon dioxide media

Glycerolysis of soybean oil was conducted in a supercritical carbon dioxide (SC-CO₂) atmosphere to produce monoglycerides (MG) in a stirred autoclave at 150–250°C, over a pressure range of 20.7–62.1 MPa, at glycerol/oil molar ratios between 15–25, and water concentrations of 0–8% (wt% of glycerol). MG, di-, triglyceride, and free fatty acid (FFA) composition of the reaction mixture as a function of time was analyzed by supercritical fluid chromatography. Glycerolysis did not occur at 150°C but proceeded to a limited extent at 200°C within 4 h reaction time; however, it did proceed rapidly at 250°C. At 250°C, MG formation decreased significantly (P<0.05) with pressure and increased with glycerol/oil ratio and water concentration. A maximum MG content of 49.2% was achieved at 250°C, 20.7 MPa, a glycerol/oil ratio of 25 and 4% water after 4 h. These conditions also resulted in the formation of 14% FFA. Conversions of other oils (peanut, corn, canola, and cottonseed) were also attempted. Soybean and cottonseed oil yielded the highest and lowest conversion to MG, respectively. Conducting this industrially important reaction in SC-CO₂ atmosphere offered numerous advantages, compared to conventional alkalicatalyzed glycerolysis, including elimination of the alkali catalyst, production of a lighter color and less odor, and ease of separation of the CO₂ from the reaction products.     

Viscosity measurement and modeling of canola oil and its blend with canola stearin in equilibrium with high pressure carbon dioxide

During enzymatic reactions carried out in supercritical CO₂ (SCCO₂) media, CO₂ can expand the liquid reactant mixture, especially lipid-type substances, due to pressure increase and dissolution of CO₂, causing viscosity reduction, and improvement of the diffusion of reactants and products. For better understanding of the transesterification reaction of canola oil and canola stearin in SCCO₂ media, the viscosity of canola oil at 40, 50, 65, and 75 °C and its blend with canola stearin (30 wt%) at 65 °C in equilibrium with high pressure CO₂ was measured up to 12.4 MPa using a rotational rheometer equipped with a high pressure cell. The solubility of CO₂ in canola oil at 40 and 65 °C and its blend with canola stearin at 65 °C was also determined at pressures of up to 20 MPa using a high pressure view cell. The viscosity of canola oil at 40, 50, 65, and 75 °C and its blend with canola stearin at 65 °C decreased exponentially to 87.2, 84.7, 74.8, 66.2, and 74.2% of its value at atmospheric pressure, respectively, with pressure increase up to 12.4 MPa. The viscosity of the samples decreased with an increase in temperature, but the effect of temperature diminished above 10 MPa. The viscosities of CO₂-expanded canola oil and its blend with canola stearin at 65 °C were similar up to 12.4 MPa. The samples exhibited shear-thickening behavior as the flow behavior index reached almost 1.2 at elevated pressures. The mass fraction of CO₂ in canola oil at 40 and 65 °C and its blend with canola stearin at 65 °C reached 24 and 21% at 20 MPa, respectively. The Grunberg and Nissan model was used to correlate the viscosity of CO₂-expanded lipid samples.     

Enzymatic Reactions in Near Critical CO2: The Effect of Pressure on Phenol Removal by Tyrosinase

The use of enzymes in supercritical CO₂ (SCCO₂) has received extensive attention in recent years. Biocatalysts have the advantage of substrate specificity and SCCO₂ offers several advantages over liquid solvents. This work deals with the utilization of SCCO₂ as a medium for the enzymatic removal of phenol from aqueous solutions using tyrosinase. Since the presence of oxygen is crucial for the enzyme-catalyzed oxidation, the substantial solvating power of SCCO₂ makes it a promising medium for such reactions. The conversion of phenol was higher at 10 MPa. Under near critical conditions (7 MPa, 35 °C), the addition of air at 5 × 10⁵ Pa of pressure improved phenol removal.     

Canola oil extracted by supercritical carbon dioxide and a commercial organic solvent

Samples of crushed and cooked canola seeds (Okapy Double Zero) were extracted using supercritical carbon dioxide (SCCO₂) (34.0 MPa and 40.0 °C) and a commercial organic solvent (AW406). Oil solubility was obtained through several stepwise extractions under the conditions of this study, and then three additional extractions were performed to measure fatty acid compositions, iodine values, chlorophyll concentrations and unsaponifiable matter. The yield of SCCO₂ extraction was lower than that after extraction with AW406 solvent, due to the incomplete SCCO₂ extraction process. Fatty acid composition analysis showed that the SCCO₂‐extracted oil was slightly higher in polyunsaturated fatty acids and lower in erucic and behenic acids. However, iodine values and unsaponifiable matter did not indicate significant differences (p >0.05) in the two extracted oils. The chlorophyll concentration of SCCO₂‐extracted oil was lower than that in the AW406 solvent, and as a result, the color of SCCO₂‐extracted oil was lighter.     

Extraction of bitumen with sub- and supercritical water

The sub- and supercritical water extractions of Athabasca oil sand bitumens were studied using a micro reactor. The experiments were carried out in the temperature range of 360–380 °C, pressure 15–30 MPa and water density 0.07–0.65 g/cm³ for 0–2 hrs. The extraction conversion of bitumens increased with solvent power and temperature. A maximum conversion of 24% was obtained after 90 min extraction at the supercritical condition. Hydrogen and carbon mono-oxide were not detected in sub-critical region but in the supercritical region. The supercritical condition was favorable to the hydrogen formation for bitumen extraction. The extraction products were upgraded relative to the original bitumens due to direct hydrolysis of low-energy linkage and H₂ formed by water gas shift reaction in supercritical condition. 18% of initial sulfur in bitumen can be removed at maximum conversion condition. The asphaltene contents of the residue were significantly higher than that of original bitumen due to preferential extraction of aromatic compounds in supercritical condition.     

Low erucic acid canola oil does not induce heart triglyceride accumulation in neonatal pigs fed formula

Canola oil is not approved for use in infant formula largely because of concerns over possible accumulation of triglyceride in heart as a result of the small amounts of erucic acid (22∶1n−9) in the oil. Therefore, the concentration and composition of heart triglyceride were determined in piglets fed from birth for 10 (n=4–6) or 18 (n=6) d with formula containing about 50% energy fat as 100% canola oil (0.5% 22∶1n−9) or 100% soybean oil, or 26% canola oil or soy oil (blend) with palm, high-oleic sunflower and coconut oil, providing amounts of 16∶0 and 18∶1 closer to milk, or a mix of soy, high-oleic sunflower and flaxseed oils with C₁₆ and C₁₈ fatty acids similar to canola oil but without 22∶1. Biochemical analysis found no differences in heart triglyceride concentrations among the groups at 10 or 18 d. Assessment of heart triglycerides using Oil Red O staining in select treatments confirmed no differences between 10-d-old piglets fed formula with 100% canola oil (n=4), 100% soy oil (n=4), or the soy oil blend (n=2). Levels of 22∶1n−9 in heart triglyceride and phospholipid, however, were higher (P<0.01) in piglets fed 100% canola oil or the canola oil blend, with higher levels found in triglycerides compared with phospholipids. The modest accumulation of 22∶1n−9 associated with feeding canola oil was not associated with biochemical evidence of heart triglyceride accumulation at 10 and 18 d.     

Lipase-catalyzed esterification of stearic acid with ethanol, and hydrolysis of ethyl stearate, near the critical point in supercritical carbon dioxide

The effect of pressure on the lipase-catalyzed reaction in supercritical carbon dioxide (SCCO₂) was investigated for the esterification of steric acid (SA) with ethanol and the hydrolysis of ethyl stearate (ES) near the critical point, ranging from 6 to 20 MPa in pressure and 35 to 60°C in temperature. The esterification rate of SA began to increase near the critical point and kept increasing steadily with an increase in pressure, reflecting the increase in SA solubility in SCCO₂. The hydrolysis rate of ES showed a maximum at a pressure near the critical point. When the reaction was carried out with an initial overall ES concentration below its solubility limit in SCCO₂, the maximum pressure shifted along the extended line of the gas-liquid equilibrium in the supercritical region in the pressure-temperature phase plane. This seems to be related to the singular behavior of some properties in SCCO₂ along this line reported in the literature. These results show the importance of pressure, as well as temperature, as a parameter to control enzyme reactions in SCCO₂.     

Restructing butterfat through blending and chemical interesterification. 1. Melting behavior and triacylglycerol modifications

Chemical interesterification of butterfat-canola oil blends, ranging from 100% butterfat to 100% canola oil in 10% increments, decreased solid fat content (SFC) of all blends in a nonlinear fashion in the temperature range of 5 to 40°C except for butterfat and the 90∶10 butterfat/canola oil blend, whose SFC increased between 20 and 40°C. The sharp melting associated with butterfat at 15–20°C disappeared upon interesterification. Heats of fusion for butterfat to the 60∶40 butterfat/canola oil blend decreased from 75 to 60 J/g. Blends with >50% canola oil displayed a much sharper drop in enthalpy. Heats of fusion were 30–50% lower on average for interesterified blends than for their noninteresterified counterparts. Both noninteresterified and interesterified blends deviated substantially from ideal solubility, with greater deviation as the proportion of canola oil increased. The change in the entropy of melting was consistently higher for noninteresterified blends than for interesterified blends. Chemical interesterification generated statistically significant differences for all triacylglycerol carbon species (C) from C₃₀ to C_56′ except for C_42′ and in SFC at most temperatures for all blends.     

Utilization of canola oil and lactose to produce biosurfactant withCandida bombicola

The prerequisites for a commercial fermentation process of biosurfactants include the use of low- or negative-cost substrates and maximum conversion yields. Under competitive market conditions, the price of canola oil is expected to decrease in response to its increased supply. Lactose, obtained from cheese whey, is a by-product of the dairy industry. In this work, canola oil with glucose or lactose as carbon sources was used as substrates to produce sophorose lipids (SLs) by means of the yeastCandida bombicola. Fermentations were conducted in either shaker flasks or 1-L Bellco (Vineland, NJ) stirred reactors for 5–7 d at 450 rpm and 30°C. The production of SLs reached 150–160 g/L in a medium consisting of 10% glucose, 10.5% canola oil, 0.1% urea and 0.4% yeast extract. When lactose was substituted for glucose, 90–110 g/L SL was obtained. The apolar SL 17-l-([2′-O-β-d-glucopyranosyl-β-d-glucopyransoyl]oxy)-octadecanoic acid 1′-4″-lactone 6′,6″-diacetate (SL-1) was the major one (73%) when canola oil was used instead of safflower oil (SL-1, 50%). Use of canola oil generally resulted in increased yields of SLs comparable to the yields obtained when safflower oil was used in the medium. Other literature reports present yields of 70 g/L and 120 g/L SLs, respectively, with these substrates.     

Synthesis of Biodiesel from Canola Oil Using Heterogeneous Base Catalyst

A series of alkali metal (Li, Na, K) promoted alkali earth oxides (CaO, BaO, MgO), as well as K₂CO₃ supported on alumina (Al₂O₃), were prepared and used as catalysts for transesterification of canola oil with methanol. Four catalysts such as K₂CO₃/Al₂O₃ and alkali metal (Li, Na, K) promoted BaO were effective for transesterification with >85 wt% of methyl esters. ICP-MS analysis revealed that leaching of barium in ester phase was too high (~1,000 ppm) when BaO based catalysts were used. As barium is highly toxic, these catalysts were not used further for transesterification of canola oil. Optimization of reaction conditions such as molar ratio of alcohol to oil (6:1–12:1), reaction temperature (40–60 °C) and catalyst loading (1–3 wt%) was performed for most efficient and environmentally friendly K₂CO₃/Al₂O₃ catalyst to maximize ester yield using response surface methodology (RSM). The RSM suggested that a molar ratio of alcohol to oil 11.48:1, a reaction temperature of 60 °C, and catalyst loading 3.16 wt% were optimum for the production of ester from canola oil. The predicted value of ester yield was 96.3 wt% in 2 h, which was in agreement with the experimental results within 1.28%.     

Response Surface Analysis and Modeling of Flaxseed Oil Yield in Supercritical Carbon Dioxide

Supercritical fluid extraction of flaxseed oil with carbon dioxide was performed. Effects of particle size, pressure, temperature and the flow rate of supercritical carbon dioxide (SC-CO₂) were investigated. Response surface methodology was used to determine the effects of pressure (30–50 MPa), temperature (50–70 °C) and SC-CO₂ flow rate (2–4 g/min) on flaxseed oil yield in SC-CO₂. The oil yield was represented by a second order response surface equation (R ² = 0.993) using the Box-Behnken design of experiments. The oil yield increased significantly with increasing pressure (p < 0.01), temperature (p < 0.05) and SC-CO₂ flow rate (p < 0.01). The maximum oil yield from the response surface equation was predicted as 0.267 g/g flaxseed for 15 min extraction of 5 g flaxseed particles (particle diameter <0.850 mm) at 50 MPa pressure and 70 °C temperature, with 4 g/min solvent flow rate. Total extraction time at these conditions was predicted as 22 min.     

Extraction and solubility evaluation of functional seed oil in supercritical carbon dioxide

Hemp (Cannabis sativa L.) seed oil is valued for its nutritional properties and for the health benefits associated with it. Its greatest feature is that the ratio of linoleic acid and linolenic acid is the desirable value of 3:1. In this research, supercritical carbon dioxide was applied to extraction of functional oil from hemp seed. In order to determine the effect of temperature and pressure on the yield of extracted components, the oil was extracted from hemp seed at temperatures between 40 and 80 °C, pressures of 20–40 MPa and a CO₂ flow rate of 3 mL/min. The solubility of hemp seed oil in SCCO₂ determined experimentally was fitted to the Chrastil equation to determine the model parameters. The solubility calculated by Chrastil equation was compared with the experimental data. Finally, the fatty acid profile of the oil was evaluated by gas chromatography-flame ionization detection (GC-FID). There are no significant differences in the compositions of five abundant fatty acid components of the oil obtained at different sampling times with SCCO₂ extraction and other extraction methods.     

Supercritical carbon dioxide extraction of evening primrose oil

The oil extracted from the seeds ofOenothera biennis L. (evening primrose) is a major commercial source of gamma-linolenic acid, a fatty acid having potential therapeutic value in the treatment of several diseases. This fatty acid is prone to oxidation and thermal rearrangement; therefore, the conventional recovery of the oil via mechanical expression and hexane extraction must be carried out under very mild and controlled conditions. In this study, supercritical fluid extraction with carbon dioxide has been employed as an alternative method to recover evening primrose oil (EPO). Extractions were performed over the pressure range of 20–70 MPa and at temperatures from 40 to 60°C, with a CO₂ mass flow rate of 18 g/min. The experimental data permitted the determination of EPO solubility in supercritical CO₂ at the tested extraction conditions. Supercritical fluid Chromatographic analysis of fractions collected during the extraction showed a subtle shift in the triglyceride composition. Fatty acid methyl ester analysis on similar fractions indicated that the fatty acid content was invariant with respect to extraction time. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Performance studies of various cracking catalysts in the conversion of canola oil to fuels and chemicals in a fluidized-bed reactor

Studies were conducted at atmospheric pressure at temperatures in the range of 400–500°C and fluidizing gas velocities in the range of 0.37–0.58 m/min (at standard temperature and pressure) to evaluate the performance of various cracking catalysts for canola oil conversion in a fluidized-bed reactor. Results show that canola oil conversions were high (in the range of 78–98 wt%) and increased with an increase in both temperature and catalyst acid site density and with a decrease in fluidizing gas velocity. The product distribution mostly consisted of hydrocarbon gases in the C₁–C₅ range, a mixture of aromatic and aliphatic hydrocarbons in the organic liquid product (OLP) and coke. The yields of C₄ hydrocarbons, aromatic hydrocarbons and C₂–C₄ olefins increased with both temperature and catalyst acid site density but decreased with an increase in fluidizing gas velocity. In contrast, the yields of aliphatic and C₅ hydrocarbons followed trends completely opposite to those of C₂–C₄ olefins and aromatic hydrocarbons. A comparison of performance of the catalysts in a fluidized-bed reactor with earlier work in a fixed-bed reactor showed that selectivities for formation of both C₅ and iso-C₄ hydrocarbons in a fluidized-bed reactor were extremely high (maximum of 68.7 and 18 wt% of the gas product) as compared to maximum selectivities of 18 and 16 wt% of the gas product, respectively, in the fixed-bed reactor. Also, selectivity for formation of gas products was higher for runs with the fluidized-bed reactor than for those with the fixed-bed reactor, whereas the selectivity for OLP was higher with the fixed-bed reactor. Furthermore, both temperature and catalyst determined whether the fractions of aromatic hydrocarbons in the OLP were higher in the fluidized-bed or fixed-bed reactor.     

Time Fractionation of Minor Lipids from Cold-Pressed Rapeseed Cake Using Supercritical CO<Subscript>2</Subscript>

This work explored the possibility of using supercritical carbon dioxide (SC-CO₂) to achieve fractionation of pre-pressed rapeseed (Brassica napus) cake oil at 30–50 MPa, at 40 or 80 °C, and increase the concentration of minor lipids (sterols, tocopherols, carotenoids) in the oil. Minor lipids are partially responsible for desirable antioxidant effects that protect against degradation and impart functional value to the oil. The weight and concentration of minor lipids in oil fractions collected during the first 60 min were analyzed. Cumulative oil yield increased with pressure, and with temperature at ≥40 MPa, but was lower at 80 °C than at 40 °C when working at pressure ≤35 MPa. Differences in solubility between the oil and minor lipids explained fractionation effects that were small for tocopherols. Unlike tocopherols, which are more soluble in SC-CO₂ than the oil, sterols and carotenoids are less soluble than the oil, and their concentration increased in the later stages of extraction, particularly at ≥40 MPa, when there was not enough oil to saturate the CO₂ phase. Because of the fractionating effects on rapeseed oil composition, there was an increase in the antioxidant activity of the oil in the second half as compared to the first half of the extraction. Consequently, this study suggests that SC-CO₂ extraction could be used to isolate vegetable oil fractions with increased functional value.     

Promotional effect of Ce on the activity of In/W–ZrO2 for selective reduction of NO x with methane

The Ce modified In/W–ZrO₂ catalysts were prepared by impregnation and mechanical mix method. Their activities for SCR of NO _x with methane were investigated. The activity of the In/W–ZrO₂ catalyst was enhanced by addition of Ce with both methods, while the promotional effect was more pronounced for catalyst prepared by mechanical mix method compared to impregnation method. The function of Ce was to improve the oxidation of NO to NO₂. The maximum NO _x conversion over the mechanical mixed catalyst can be stabilized at 74% at 450 °C in a dry gas flow and 37% at 500 °C in wet flow (24,000 h⁻¹). For the impregnated catalysts, Ce was found to compete with In to adsorb on strong acid site over W–ZrO₂ support and inhibited the formation of InO⁺, which resulted in the lower activity of these catalysts than mechanical mixed catalysts.     

Microemulsion-Based Vegetable Oil Detergency Using an Extended Surfactant

This work examined the use of a single extended surfactant in the microemulsion-based detergency of vegetable oils. The results showed that good canola oil detergency (>80%) was achieved at 25 °C using a single extended surfactant (C_14,15–8PO–SO₄Na) at concentrations as low as 125 ppm, i.e., significantly lower than the surfactant concentration range of 500–2,500 ppm reported in other microemulsion-based detergency work. It was found that the maximum detergency (95%) was achieved in the type II microemulsion region. These results demonstrate that the microemulsion-based extended surfactant formulation is a promising approach for vegetable oil detergency at low temperature.