Optimization of Solvent Extraction of Moringa (Moringa Oleifera) Seed Kernel Oil Using Response Surface Methodology

Extraction of seed kernel oil from moringa (Moringa oleifera) was investigated with hexane, petroleum ether and acetone as the first extraction medium at various kernel particle size, extraction temperature and residence time, which were called as independent variables. Central composite rotatable design (CCRD) of experiments was used to study the effect of solvent type, particle size, extraction temperature and residence time of solvent on the oil yield, which was called as dependent variable. The maximum oil yield of 33.1% for hexane, 31.8% for petroleum ether and 31.1% for acetone was obtained. Among the three solvents, hexane yielded the maximum oil from moringa seed kernels. Among three process parameters studied, particle size had the most significant effect on the oil yield followed by extraction temperature and time for all the solvents. Response surface methodology technique was used to optimize the independent variables for maximum oil extraction. From the optimized values of particle size (0.62 mm), extraction temperature (56.5°C) and residence time (7 h), maximum oil yield obtained was 33.5%, using hexane. Optimized values of independent variables for maximum yield were varied for other two solvents. This protocol provides improved opportunities for the medicinal use of moringa oil in addition to its popularity as a vegetable in south Asia.     

The Viscosity of cottonseed oil,fractionation solvents and their solutions

Cold fractionation of cottonseed oil is made difficult by the high viscosity of the oil. This study was aimed at demonstrating the effect of solvents on the viscosity of mixtures between 0°C and 25°C with a view to facilitating the fractionation of refined cottonseed oil. The solvents used were acetone, methylethylketone, methylisobutylketone, hexane and heptane. Measurements of viscosity were carried out by means of a capillary viscometer. The ratio of the viscosity of cottonseed oil to that of pure solvents is of the order of 300. The viscosities of solutions of various ratios of solvent to oil (1/3, 1/1, 3/1) are between those of cottonseed oil and the pure solvents. The effect of the solvent/oil ratio overrides that of solvent nature. The effect of solvent in reducing the viscosity of cottonseed oil is by descending order: acetone, hexane, methylethylketone, heptane, methylisobutylketone.     

Cottonseed extraction with mixtures of acetone and hexane

Cottonseed flakes were extracted with mixtures of n-hexane and acetone, with the concentration of acetone varying between 10 and 75%. Adding small amounts of acetone (≤25%) to n-hexane significantly increased the extraction of free and total gossypol from cottonseed flakes. Sensory testing detected no difference in the odor of cottonseed meals produced either by extraction with 100% n-hexane or by extraction with a 10∶90 (vol/vol) mixture of acetone/hexane. More than 80% of the free gossypol was removed by the 10∶90 mixture of acetone/hexane, whereas pure n-hexane extracted about 47% of the free gossypol from cottonseed flakes. A solvent mixture containing 25% acetone removed nearly 90% of the free gossypol that was removable by extraction with pure acetone; the residual meal had only a minimal increase in odor. In contrast, cottonseed meals produced by extraction with pure acetone had a much higher odor intensity. The composition of the cottonseed crude oil was insignificantly affected by the acetone concentration of the extraction solvent. The results indicate that mixtures of acetone and n-hexane can be used as extraction solvents to produce cottonseed crude oil without the concomitant development of odorous meals.     

Alternative hydrocarbon solvents for cottonseed extraction: Plant trials

Hexane has been used for decades to extract oil from cottonseed and is still the solvent of choice for the edible-oil industry. Due to increased regulations as a result of the 1990 Clean Air Act and potential health risks, the edible-oil extraction industry urgently needs an alternate hydrocarbon solvent to replace hexane. Based on laboratory-scale extraction tests, two hydrocarbon solvents, heptane and isohexane, were recommended as potential replacements for hexane. A cottonseed processing mill with a 270 MT/day (300 tons/day) capacity agreed to test both solvents with their expander-solvent process. Extraction efficiencies of isohexane and heptane, judged by extraction time and residual oil in meal, refined and bleached color of miscella refined oil, and solvent loss, were comparable to that of hexane. However, fewer problems were encountered with the lower-boiling isohexane than with the higher-boiling heptane. With isohexane, the daily throughput increased more than 20%, and natural gas consumption decreased more than 40% as compared to hexane.     

Effect of the extraction solvent polarity on the sesame seeds oil composition

This study highlights the effect of solvent polarity on the yield (Y%) and properties of oil extracted from Algerian sesame seeds. Extractions were carried out under Soxhlet conditions with the following solvents: hexane (Hx), ethanol (Eth), acetone (Ac), dichloromethane (Di), isopropanol (Iso), hexane:isopropanol (Hx:Iso), and chloroform:methanol (Chf:Me). The sesame oil yield obtained using different solvents ranged from 28.86 to 52.83%. Fatty acids and sterols analyses were performed by GC on capillary column. γ‐Tocopherol was the major tocochromanol compound detected by HPLC‐fluorescence. Fourteen fatty acids were identified, with the predominance of oleic and linoleic acids. The main sterol in sesame oil was β‐sitosterol, followed by stigmasterol, campesterol, and Δ⁵‐avenasterol which were present in lower concentrations. High correlations were found between arachidic, gadoleic, behenic, and lignoceric acids concentrations; these results were explained by the metabolic biosynthesis pathway of the biologically active long‐chain PUFA by successive elongation and desaturation. Principal component analysis (PCA) of the data obtained from sesame oil composition enabled an easy comparison of the different extraction solvents, and correlated their properties with the most characteristic components of the extracted oils with a view to understand solvent–oil interaction, and to establish the effects of extracting solvent on such oil composition. Practical applications: This study showed that the choice of solvent depends largely on the desired fraction to be extracted. Sesame oil was better extracted with less‐polar solvents but membrane‐associated lipids are more polar and require polar solvents capable of breaking hydrogen bonds or electrostatic forces. Owing to the differences in solvent capacity, the fatty acids, sterols, and tocopherols extracted along with the oil vary, leading to differences in the quality of the extracted oil. The results obtained in this study could be applied in industrial extraction to encourage the use of alternative extraction solvents.     

Ambient-temperature extraction of rice bran oil with hexane and isopropanol

Hexane and isopropanol were compared as solvents for use in ambient-temperature equilibrium extraction of rice bran oil (RBO). Isopropanol was as effective as hexane in extracting RBO when 20 mL of solvent was used to extract 2 g of bran. Free fatty acid levels were 2–3% in both solvents and similar to that previously reported for hexane extraction of RBO hexane extraction by this method. Larger-scale extractions with 30 g of bran and 150 mL of solvent produced oil with a similar free fatty acid content and a phosphorus level of approximately 500 ppm. The oil extracted with isopropanol was significantly more stable to heat-induced oxidation than hexane-extracted oil. Antioxidants that are more easily extracted by isopropanol than hexane may be responsible for the increased stability.     

Membrane processing of crude vegetable oils: Pilot plant scale remoyal of solvent from oil miscellas

The recovery of solvents used in the extraction step of edible oil processing is required for economical, environmental, and safety considerations. The miscella (mixture of extracted oil and solvent) exits the extractor at 70 to 75 wt% solvent content. Currently, the solvent is recovered by distillation. This paper reports the results of a study on separation of vegetable oils from commercial extraction solvents using various types of Reverse Osmosis (RO) and Ultrafiltration (UF) membranes. Solvent permeation rates and separation performances of various RO and UF membranes were determined by using ethanol, isopropyl alcohol and hexane as the solvents. One membrane exhibited a flux of 200 GFD (ethanol) with 1% oil remaining in the permeate. However, hexane rapidly deteriorated all but one of the membranes tested. The membrane that was compatible with hexane had a low flux and unacceptably low oil retention. Industrial-scale membranes were also evaluated in pilot plant trials. A hexane separation was attempted with a hollow-fiber membrane unit, and it was noted that the pores of the fibers swelled almost closed. Some of the commercially available membranes selectively removed solvent (ethanol or isopropanol) from the edible oil miscellas with reasonable flow rates. The research reported has shown that membranes manufactured from polyamide were the least affected by hexane. Fluxes achieved during solvent-oil separations were increased by increases in either temperature or pressure and decreased by increases in oil concentration in the feed. The processing temperature affected the percentage of oil in solution in either ethanol or isopropanol as well as the viscosity of the feed. Both of these factors in turn influenced the flux achieved. Approximately 2 trillion Btu/yr could be saved using a hybrid membrane system to recover solvents used in the extraction step of crude oil production. Studies to date report marginal success. The development of hexane-resistant membranes may make this application viable.     

Performance of Nanofiltration Membranes for Solvent Purification in the Oil Industry

The extraction stage of edible oil in the oil industry is commonly performed by using toxic solvents (e.g. hexane) and processes with high energy consumption (e.g. distillation, evaporation) to recover the solvent, which represents around 70–75 wt% in the oil–solvent mixture. In this paper, a membrane-based extraction method using nanofiltration (NF) membranes is presented. Commercial nanofiltration membranes made of different polymers (Desal-DK-polyamide NF from GE-osmonics^®, NF30 polyethersulfone NF from Nadir^®, STARMEM^TM122 polyimide from MET^® and SOLSEP NF030306 silicone base polymer SOLESP^®) were selected and tested to recover the solvent from soybean oil/solvent (10–20–30% w/w oil) mixtures at various separation pressures and constant temperature in a dead-end filtration set up. The selection of the solvent was made in order to compare solvents obtainable from renewable resources, such as ethanol, iso-propanol and acetone, with solvents traditionally used in the industry (i.e. cyclohexane and n-hexane). The structural stability of the membranes towards the different solvents used in this work was verified visually, by the variation of the membrane area and by means of permeate flux assessments. Desal-DK and NF30 showed poor filtration performance and even visible defects after exposure to acetone but a good performance was obtained for the nanofiltration membranes STARMEM^TM122 and SOLSEP NF030306 with ethanol, iso-propanol and acetone. For example, considering a mixture with 30% edible oil in acetone, STARMEM^TM122 shows a flux and oil rejection of 16.8 L m^?2 h and 70%, respectively. For the same conditions, SOLSEP NF030306 exhibited a flux of 4.8 L m^?2 h with 78% rejection, which shows the potential application of nanofiltration membranes in the oil industry.     

Phase relations pertaining to the solvent winterization of cottonseed oil in hexane and in acetone-hexane mixtures

Summary Systematic phase relation data pertaining to the solvent winterization behavior of a refined cottonseed oil have been obtained for two additional solvents; namely, commercial hexane and a mixed solvent consisting of 85% by weight of acetone and 15% of hexane. Graphs have been constructed to show the effect of oil-solvent ratio, chilling temperature, holding-time, and agitation on the percentage of solid removed, the degree of winterization and the settling qualities of the solid separating. These data, with those previously reported for acetone (1), afford a basis for the selection of the optimum conditions and procedures in the application of solvent winterization to cottonseed oil and bring out the relative advantages, disadvantages, and limitations of the three solvents. The acetone-hexane mixture seems to combine the advantages and eliminate the disadvantages of either of these solvents alone. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Hexane and heptane as extraction solvents for cottonseed: A laboratory-scale study

For many years, commercial-grade hexane has been the preferred solvent for extracting oil from cottonseed. Recent environmental and health concerns about hexane may limit the use of this solvent; therefore, the need for a replacement solvent has become an important issue. Heptane is similar to hexane, but does not have the environmental and health concerns associated with the latter. On a laboratory scale, delinted, dehulled, ground cottonseed was extracted with hexane and heptane. The solvent-to-meal ratio was 10:1 (vol/wt). The yield and quality of the oil and meal extracted by heptane were similar to that extracted by hexane. Extraction temperature was higher for heptane than for hexane. A higher temperature and a longer time were required to desolventize miscella from the heptane extraction than from the hexane extraction. Based on these studies, heptane offers a potential alternative to hexane for extracting oil from cottonseed.     

Alternative hydrocarbon solvents for cottonseed extraction

Hexane has been used for decades to extract edible oil from cottonseed. However, due to increased regulations affecting hexane because of the 1990 Clean Air Act and potential health risks, the oil-extraction industry urgently needs alternative hydrocarbon solvents to replace hexane. Five solvents,n-heptane, isohexane, neohexane, cyclohexane, and cylopentane, were compared with commercial hexane using a benchscale extractor. The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36 mL/min/sq cm (9 gal/min/sq ft) at a temperature of 10 to 45°C below the boiling point of the solvent. After a 10-min single-stage extraction, commercial hexane removed 100% of the oil from the flakes at 55°C; heptane extracted 100% at 75°C and 95.9% at 55°C; isohexane extracted 93.1% at 45°C; while cyclopentane, cyclohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35, 55, and 35°C, respectively. Each solvent removed gossypol from cottonseed flakes at a different rate, with cyclopentane being most and neohexane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents, heptane and isohexane are the alternative hydrocarbon solvents most likely to replace hexane. Presented in part at the AOCS Annual Meeting & Expo, Atlanta, Georgia, May 1994.     

Canola Oil with High Antioxidant Content Obtained by Combining Emerging Technologies: Microwave,Ultrasound, and a Green Solvent

In this work, the ultrasound‐assisted extraction (UAE) of canola oil from canola seeds pretreated with microwaves using ethanol 99% as solvent is studied. Different process parameters are evaluated, such as extraction time, temperature, solid:solvent ratio, and ultrasound amplitude, optimizing the process using response surface methodology. Under optimum conditions, the extraction time is decreased by up to 75% with respect to conventional extractions, obtaining an oil with a higher content of total tocopherols and canolol, and with oxidation indexes within the established standard limits. The addition of a microwave pretreatment to the UAE with ethanol 99% shows a synergic effect between both processes, improving the oil yield. The results obtained in this study show the potential of the use of UAE for the extraction of canola oil using a green solvent, reducing processing times, environmental pollution, and achieving an oil of high quality and antioxidant concentration. Practical Application: The industrial use of petroleum‐derived solvents such as hexane has problems concerning sustainability, environment, and safety. In recent years, the use of “green” solvents for the extraction of vegetable oils began to be studied; however, it is necessary to develop stages that allow improving the extraction process by increasing the yield, reducing the processing times, and optimizing the oil quality. In this sense, ultrasound allows to shorten the extraction times while microwave pretreatments applied to canola seeds generate an increase in the concentration of antioxidants in the oil, facilitating the implementation of a “green” process in the industrial production.     

First approach on rice bran oil extraction using limonene

Edible oil extraction with petroleum derivatives as solvents has caused safety, health, and environmental concerns everywhere. Thus, finding a safe alternative solvent will have a strong and positive impact on environments and general health of the world population, considering the scale of oil extraction operations worldwide. The extraction of oil from rice bran by d‐limonene and hexane (for comparison) has been carried out at their respective boiling points at various solvent‐to‐meal ratios and for various extraction times. The preliminary data suggested that the optimum solvent‐to‐meal ratio and extraction time required for d‐limonene extraction of rice bran oil to be 5:1 and 1 h respectively. The initial quality characteristics (free fatty acid content, oil color, phospholipid content) of crude oil extracted under these optimum conditions were analyzed using various analytical methods based on the standard methods of AOCS and were found to be comparable to the oil extracted with hexane. The initial positive result has paved the way for further studies on issues related to meal qualities as well as to a scale‐up of the method in the near future.     

Extraction of jojoba oil by pressing and leaching

Jojoba oil extraction by pressing alone, pressing followed by leaching, and leaching alone were investigated. The extraction process by first and second pressing followed by leaching gave about 50% by weight oil with reference to total seed, which is in agreement with what has been reported previously. The extraction by leaching process was carried out using different solvents. These solvents were; hexane, benzene, toluene, petroleum ether, chloroform, and isopropanol. Hexane, benzene, and petroleum ether gave the highest yield (all about 50% by weight oil with reference to total seed), but when cost is considered, petroleum ether is recommended as the best solvent to leach jojoba oil. The yield obtained in this work for leaching by hexane and benzene are 3–5% and about 10% for isopropanol more than those reported in the literature. Traces of solvent remained with the extracted oil after simple distillation followed by a second stage distillation via a Rotavapour apparatus. These traces slightly affected some of the oil properties such as pour point and flash point.     

Jatropha curcas L. oil extracted by switchable solvent N,N-dimethylcyclohexylamine for biodiesel production

Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction from oilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO_2,and can be used for oil extraction. N, N-dimethylcyclohexylamine(DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were:1:2 ratio of seed mass to DMCHA volume, 0.3–1 mm particle size, 200 r·min-1agitation speed, 60 min extraction time, and 30 °C extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and is much less volatile. By bubbling CO_2 under 1 atm and 25 °C for 5 h, the oil was separated, and DMCHA was recovered after releasing CO_2 by bubbling N_2 under 1 atm and 60 °C for 2 h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.     

Extraction of lipids from cotronseed tissue: I. Comparison of hexane-acetone-water,its nonqueous components and chloroform-methanol

Flaked cottonseed was extracted with chloroform-methanol-water, chloroform-methanol, hexane-acetone-water, hexane-acetone, hexane and acetone. Amounts of total material in the miscellae were greatest with chloroform-methanol-water and decreased to acetone in the order given above. The first three solvents extracted 6% more neutral oil and over 100% more lipophilic phosphorus than the latter three solvents. All solvents showed similar rates of extraction, each removed over 70% of extractables with the first of four passes.     

Solvent effects on phase transition behavior of canola oil sediment

Differential scanning calorimetry (DSC) was used to study the melting and crystallization behavior of waxy sediment in canola oil and in mixtures (1:1, w/w) of oil and acetone or hexane under dynamic heating/cooling regimes. In the presence of a solvent, the DSC melting peak of sediment shifted to lower temperatures, suggesting that sediment was more soluble in the solvent/oil systems than in oil alone. This effect was greater with hexane than with acetone. The influence of a solvent on crystallization was more complex. With inclusion of hexane, the crystallization temperature of sediment was always lower than that in oil. With acetone, however, the crystallization temperature of sediment was slightly lower at high sediment content, but higher at low sediment content than in oil alone. The differences in melting and crystallization behavior of sediment in canola oil and the solvent/oil systems were attributed to solubility and viscosity effects. Variation in the crystalline solid structures of sediment was not evident from the melting enthalpies associated with the phase transformation.     

Biorenewable solvents for vegetable oil extraction

A review of the literature pertaining to possible alternatives for hexane as solvent in the extraction of vegetable oils was made. The review was restricted to solvents obtainable from renewable resources and included the most recent technological advances in oil extraction processes. The most promising systems surveyed were based on the use of water, alcohols, ketones, halocarbons, or of liquified and supercritical gases as solvents for oils. Presented at the 31st Oilseed Processing Clinic March 1982, New Orleans, LA.     

Extraction of corn oil by three petroleum solvents

Summary and conclusions Rate-extractions of corn germ oil by heptane, isoheptane, and hexane at the same temperature showed the latter two to be better solvents than heptane. Extraction rate increased with the temperature. Countercurrent extraction in a continuous laboratory pilot plant showed hexane at 157°F. apparently equal to iso-heptane at 192°F. It is suggested that the boiling of the hexane at 157°F. might account for the better extraction. It can be concluded that hexane is at least as good a solvent for the extraction of corn oil from whole germ as is iso-heptane.     

Alternative Bio-Based Solvents for Extraction of Fat and Oils: Solubility Prediction,Global Yield,Extraction Kinetics,Chemical Composition and Cost of Manufacturing

The present study was designed to evaluate the performance of alternative bio-based solvents, more especially 2-methyltetrahydrofuran, obtained from crop’s byproducts for the substitution of petroleum solvents such as hexane in the extraction of fat and oils for food (edible oil) and non-food (bio fuel) applications. First a solvent selection as well as an evaluation of the performance was made with Hansen Solubility Parameters and the COnductor-like Screening MOdel for Realistic Solvation (COSMO-RS) simulations. Experiments were performed on rapeseed oil extraction at laboratory and pilot plant scale for the determination of lipid yields, extraction kinetics, diffusion modeling, and complete lipid composition in term of fatty acids and micronutrients (sterols, tocopherols and tocotrienols). Finally, economic and energetic evaluations of the process were conducted to estimate the cost of manufacturing using 2-methyltetrahydrofuran (MeTHF) as alternative solvent compared to hexane as petroleum solvent.