Simultaneous Enzymatic Transesterification and Esterification of an Acid Oil Using Fermented Solid as Biocatalyst

This work studied the enzymatic synthesis of fatty acid ethyl esters (FAEE) for potential use as biodiesel via simultaneous esterification and transesterification of acid oil from macaúba in a solvent-free system. A fermented and dry babassu cake with lipase activity from Rhizomucor miehei was used as biocatalyst. FAEE content above 85% was achieved after 96 h of reaction with enzyme loading of 13 U per g of oil, 120 mmol of hydrous ethanol (95% ethanol and 5% water)/20 mmol of oil (molar ratio ethanol:oil of 6:1), at 40 °C. After two consecutive enzymatic reactions, 90.8 wt% FAEE content was obtained. These results demonstrate a promising transesterification/esterification method for FAEE production from an acid and low-cost oil and the process has potential to decrease the costs of enzymatic biodiesel production.     

Optimization of rubber seed oil extraction using liquefied dimethyl ether

The objective of this study was to find the optimal condition for the extraction of rubber seed oil (RSO), using liquefied dimethyl ether (DME). Response surface methodology with a spherical central composite design model was employed to determine the optimal extraction condition, consisting of a seed moisture content (%wt), a solvent to solid ratio (g/g), and an extraction temperature (°C). A quadratic regression equation suggested the optimal extraction condition was a moisture content of 56.4%wt, a solvent to solid ratio of 6.7 (g/g), and a temperature of 33.3?°C. At this condition, the RSO yield predicted by the model gave a slight deviation of 0.68% from the experimentally validated results (41.48 versus 41.20%). RSO has a kinematic viscosity of 36.8 cSt, an acid value of 10.7 KOH/g oil, a fatty acid content of 5.1% and an unsaturated fatty acid content of 80%, resulting in the potential production of biodiesel, biolubricants, and biodegradable plastics.     

Biodiesel Feedstock from Emulsions Produced by Aqueous Processing of Yellow Mustard

The multi-stage treatment of stable oil-in-water emulsions produced during non-enzymatic aqueous processing of dehulled yellow mustard flour with cyclic ethers [tetrahydrofuran (THF) and 1,4-dioxane] was investigated to produce a single-phase oil-solvent-water miscella suitable for biodiesel production. While the single-stage treatment of yellow mustard emulsion recovered 97 % and 95 % of the oil by using 4:1 THF:oil and 9:1 dioxane:oil weight ratios, respectively, miscella phases containing more than 7 % water formed, which made them unsuitable as biodiesel feedstock. Multi-stage treatments of the emulsion using lower THF:oil and dioxane:oil weight ratios were further developed to produce oil-solvent-water miscella phases with low water content. While three-stage extraction of emulsions using 0.5:1, 1:1, 1.5:1, and 2:1 dioxane:oil weight ratios did not destabilize the emulsion, three-stage extraction using 0.5:1 and 0.75:1 THF:oil weight ratios effectively recovered over 97 % of the oil, resulting in the production of oil-rich miscella phases containing only 1 % and 1.5 % water, respectively. These miscella phases were analyzed for free fatty acid and phosphorus contents and proved to be excellent feedstocks for the preparation of high-purity methyl esters through single-phase base-catalyzed transmethylation.     

In situ transesterification of coconut oil using mixtures of methanol and tetrahydrofuran

The conventional biodiesel production method requires oil extraction followed by transesterification with methanol. The solubility of vegetable oils in methanol is low which decreases the overall rate of reaction. To eliminate the oil extraction step and improve the overall reaction rate, simultaneous extraction, esterification and transesterification were conducted by directly mixing methanol and tetrahydrofuran (THF) co-solvent and sulfuric acid catalyst with ground, desiccated coconut meat (copra) in a batch process and continuing the reaction until the system reached steady state. After separation of the mixture, yield was obtained by measuring the content of triglycerides, diglycerides and monoglycerides in the biodiesel phase. The yield increases with THF:methanol ratio, methanol:oil molar ratio and temperature. Within the range of conditions tested, the highest yield achieved was 96.7% at 60 °C, THF:methanol volume ratio of 0.4 and methanol:oil molar ratio of 60:1. The methanol:oil molar ratio is necessarily high in order to completely wet the copra mass, but is still lower than in previous studies by other researchers on in situ transesterification. Product assays show that the resulting biodiesel product is similar to conventionally produced coconut biodiesel. The results indicate that the in situ transesterification of copra using methanol/THF mixtures merits further study.     

Optimum process and energy density analysis of canola oil biodiesel synthesis

Biodiesel has been recommended as an environmentally benign alternative fuel because it emits a comparatively small amount of air pollutants. Biodiesel can be processed from canola oil, which has a low liquefaction temperature owing to its high unsaturated fatty acid content, which also limits its engine-clogging effects. In this study, optimum conditions such as the amount of methanol, the alkali catalyst, and the reaction temperature were determined for production of biodiesel from canola oil. A maximum biodiesel yield was shown at an oil/methanol mole ratio of 1:6. The optimum amount of catalyst was 1 wt% of potassium hydroxide. The biodiesel yield and the methyl ester content were high when the reaction temperature was 55 °C. The consolute temperature for determining the maximum biodiesel yield was proposed in consideration of the boiling point of methanol. The energy density was analyzed for the final products of biodiesel in comparison to the raw canola oil and other plant oil based biodiesels.     

Aqueous Extended-Surfactant Based Method for Vegetable Oil Extraction: Proof of Concept

The use of hexane to extract vegetable oil from oilseeds is of growing concern due to hexane’s environmental impact and because of worker exposure concerns. The goal of our work is to demonstrate that the aqueous extended-surfactant-based method is a viable alternative for vegetable oil extraction. In our method, ground oilseeds were dispersed in the aqueous surfactant solution, allowing the oil to be liberated from the seeds as a separate phase from the aqueous phase. The impact of pH, shaking intensity, shaking time and seed to liquid ratio on oil yield are presented. Extended-surfactants are a new type of surfactant with propoxylate (PO) and/or ethoxylate (EO) groups inserted between the hydrophilic head and the hydrophobic alkyl chain of the surfactant molecule. This unique structure of extended-surfactants enables them to produce ultralow interfacial tension with vegetable oils. We have found that at low aqueous concentrations (less than 0.3 wt%), extended-surfactant solutions are able to produce ultralow interfacial tension between aqueous extraction and vegetable oil phases. At optimum condition (seed to liquid ratio of 1–5, 30 min extraction at 150 shakes/min and 30 min centrifugation at 2,170×g) we achieved 93–95% extraction efficiency for peanut and canola oils at 25 °C. The oil quality produced from the aqueous extended-surfactant-based method was found to be comparable or even superior to that obtained from hexane-based extraction, further demonstrating the viability of aqueous extended-surfactant based extraction.     

Minor Constituents in Canola Oil Processed by Traditional and Minimal Refining Methods

The minimal refining method described in the present study made it possible to neutralize crude canola oil with Ca(OH)₂, MgO, and Na₂SiO₃ as alternatives to NaOH. After citric acid degumming, about 98 % of the phosphorous content was removed from crude oil. The free fatty acid content after minimal neutralization with Ca(OH)₂ decreased from 0.50 to 0.03 %. Other quality parameters, such as peroxide value, anisidine value, and chlorophyll content, after traditional and minimal neutralization were within industrial acceptable levels. The use of Trisyl silica and Magnesol R60 made it feasible to remove the hot-water washing step and decreased the amount of residual soap to <10 mg/kg oil. There were no significant changes in chemical characteristics of canola oil after using wet and dry bleaching methods. During traditional neutralization, the total tocopherol loss was 19.6 %, while minimal refining with Ca(OH)₂, MgO, and Na₂SiO₃ resulted in 7.0, 2.6, and 0.9 % reductions in total tocopherols. Traditional refining removed 23.6 % of total free sterols, while after minimal refining free sterols content did not change. Both traditional and minimal refining resulted in almost complete removal of polyphenols from canola oil. Total phytosterols and tocopherols in two cold-pressed canola oils were 774 and 836 mg/100 g, and 366 and 354 mg/kg, respectively. The minimal refining method described in the present study was a new practical approach to remove undesirable components from crude canola oil meeting commercial refining standards while preserving more healthy minor components.     

Improving Waste Cooking Oil Quality for Biodiesel Production with the Ethanolic By-product of Soybean Oil Extraction

Waste cooking oils (WCO) can be used as feedstock for biodiesel (fatty acid ethyl or methyl esters—FAEE or FAME) production. Their usual high acidity, high moisture, and low stability can impair the reaction yield and generate a low-quality biodiesel. Here, we performed liquid–liquid washings using WCO and ethanol-based solvents with the goal of generating oil-rich miscella as FAEE feedstocks with a higher quality than WCO. Three different solvents were evaluated: 99% ethanol, 95% ethanol, and the soybean oil extraction ethanolic phase (SEP), a by-product with immense unexplored antioxidant potential obtained by extracting soybean oil using ethanol. Washings were performed in a 1000 mL flat-bottom flask at 78.1 °C, using a 1:2 (w/v) oil/solvent ratio, under magnetic stirring (1200 rpm) for 10 min. Ethyl esters were prepared via homogeneous alkali transesterification using WCO and oil-rich miscella as feedstocks. Treatments reduced the acid value by 40–61% and the peroxide value by 15–50%. Improvements in feedstock quality generated 24–54% higher biodiesel yields. The oil-rich phase produced with SEP was 15% more resistant to oxidation than WCO. This was attributed to the transference of isoflavones from the SEP. However, biodiesel from treated samples presented equal or lower oxidative stability than FAEE from WCO. High-performance liquid chromatography (HPLC) analysis showed that no isoflavones remained in biodiesel after purification. Pretreatment of WCO with ethanol-based extracts such as the SEP has great potential to improve WCO quality for biodiesel production as it can be a source of plant-based antioxidants.     

Using SPME-GC/MS to Evaluate Acrolein Production in Cassava and Pork Sausage Fried in Different Vegetable Oils

This work presents the quantification of acrolein in cassava and pork sausage fried (temperature of 170 °C) in five different vegetables oils: canola, palm, sunflower, soybean and corn using a method of solid-phase microextraction (SPME) combined with gas chromatography and mass spectrometry. The results showed that the highest concentration of acrolein was found in samples fried in sunflower oil and canola oil. The concentration of acrolein in pork sausage (3.7 and 2.0 ng/g/g) was lower than in cassava (10.2 and 3.8 ng) when fried in sunflower and soybean oils, respectively. In contrast, when the denser oils (canola and palm) were used for frying, the concentration of acrolein in pork sausage (6.3 and 3.8 ng/g) was higher than in cassava (3.7 and 2.8 ng/g). Using corn oil, the concentrations of acrolein in both cassava and sausage were similar (approximately 5 ng/g). The viscosity of the oil, the fatty acid composition, especially the level of saturated and unsaturated fatty acids from the food, and oil uptake are factors that influence the acrolein concentration found in fried food.     

Attenuation of sinapic acid and sinapine-derived flavor-active compounds using a factorial-based pressurized high-temperature processing

De-oiled canola meals are sources of protein-containing flavor-active phenolic compounds. Conventional canola oil processing utilizes an excess amount of solvents and is associated with the release of high-intensity bitter flavor-active phenolic compounds, limiting the use of the canola meal. Recent advances in the extraction and isolation of the bitter favor-active phenolic compounds from canola by-products produce protein isolates, however, would benefit the industry by producing a side-stream ingredient rich in phenolics. High temperature and pressure-aided processing, namely the accelerated solvent extraction (ASE) was investigated to extract the flavor-active bitter molecules from the canola meal. The extractability of flavor-active phenolic compounds including the major sinapates, kaempferol derivatives, and other thermo-generative compounds including thomasidioc acid (TA) was evaluated. The effects of temperature, solvent extractant and concentration, and the particle size of the meal were examined on the extraction efficiency of these phenolic compounds. Extraction temperature (180°C) was the primary determinant (p < 0.05) for the attenuation of major sinapates including sinapine and sinapic acid. Both ethanol and methanol extractants at a concentration of 70% (v/v) significantly (p < 0.05) extracted the flavor-active phenolic compounds. The pressurized high temperature through optimized ASE conditions attenuated the bitter undesirable flavor-active phenolic molecules from canola meal, thereby facilitating a potential value-added phenolic-rich by-product.     

Cooking and Sun Drying Effects on Properties of Allanblackia stanerana Kernels’ Oil

Previous studies have evaluated the nutritive potential of Allanblackia oils. Oil extraction from Allanblackia is done after a pretreatment of the kernels which has an influence on oil quality. In Cameroon, the pretreatment consists of cooking, followed by drying of the almonds in the sun. The oil is either edible or used as a body cream. Because of these important applications, it is necessary to determine treatment conditions that maximize extraction yields and preserve its quality. This study was aimed at finding the mathematical models that simulate the best pre-treatment conditions. The use of multiple linear regression analysis allowed developing satisfactory models and surface response plots that predict the evolution of the extraction rate as well as the quality of the extracted oil, depending on cooking and sun drying times. The coefficients of correlation obtained were 72.03 % for water content; 53.06 % for extraction yield; 71.06 % for acid; 76.48 and 83.29 % for iodine and refractive values respectively, indicating a suitable model of the experiment according to the studied variables. The response surface curves were superimposed to obtain a single optimal range that satisfies all response factors. The average cooking time of 12.5 min and the mean residence time of 8.5 days drying gave the following optimal values for the different response factors studied: moisture content 21.60 %; oil yield 70.69 %; refractive index 1.4546; iodine value 34.72; and acid value 0.38 mg KOH/g oil. The conditions to obtain a maximum extraction yield and low acidity were those that gave a residual water content of about 10–15 %. The quality indicators measured in this work generally remained within the threshold.     

Impact of the North Dakota Growing Location on Canola Biodiesel Quality

Canola biodiesel (fatty acid methyl esters, FAME) may have superior cold flow properties when compared to other biodiesel feedstocks, which is attributed to canola’s high unsaturated and low saturated fat content. The objective of this study was to evaluate canola biodiesel fatty acid composition, cloud point (CP) and oil stability index (OSI) among several ND locations and production years. In Experiment 1, bulked canola varieties from seven growing seasons (2003–2009) were analyzed and in Experiment 2 a single canola variety (Interstate Hyola 357RR) harvested at two locations (2003–2005, and 2007) were analyzed. FAME was produced directly from seed via in situ alkaline transesterification methods. CP ranged from −0.1 to −2.4 °C and was significantly impacted by year and location. FAME generally met the ASTM B100 specification for OSI (3 h), but increased seed storage decreased stability. No significant differences were detected in FAME composition, and iodine value ranged from 108 to 123 g I₂/100 g. A significant relationship between fat saturation and location with CP and stability was not detected among the samples in this study. Variation in fatty acid composition was small; thus, the significant variability in CP and OSI suggests either differences in minor constituents (antioxidants, waxes) or environmental seed stress impacted biodiesel quality. Our study supports the value of examining biodiesel quality in a canola breeding program.     

Optimization of an Aqueous Extraction Process for Pomegranate Seed Oil

Response surface methodology employing a five-level, four-variable central composite rotatable design was applied to study the effects of extraction time, extraction temperature, pH and water/solid ratio on the extraction yield of pomegranate seed oil using an aqueous extraction approach. In addition, quality indices, fatty acid composition and antioxidant activity of the obtained oil were studied and compared with those of typical hexane-, cold press- and hot press-extracted oil. Aqueous extraction resulted in the maximum oil recovery of 19.3% (w/w), obtained under the following critical values: water/solid ratio (2.2:1.0, mL/g), pH 5.0, extraction temperature = 63 °C and extraction time = 375 min. This yield is lower than that obtained via hexane extraction (26.8%, w/w) and higher than the yields from cold press (7.0%, w/w) and hot press (8.6%, w/w) extraction. A comparison of the characteristics of the oils based on extraction method revealed that the unsaturated fatty acid content was highest for the oil obtained by aqueous extraction. In addition, higher levels of iodine and peroxide and lower levels of acid, p-anisidine and unsaponifiable matter were observed. The oil obtained with aqueous extraction also exhibited higher antioxidant activity than oils obtained by hexane or hot press extraction.     

Biodiesel Production from Soybean Oil Catalyzed by Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>

In the present study, we synthesized biodiesel from soybean oil through a transesterification reaction catalyzed by lithium carbonate. Under the optimal reaction conditions of methanol/oil molar ratio 32:1, 12 % (wt/wt oil) catalyst amount, and a reaction temperature of 65 °C for 2 h, there was a 97.2 % conversion to biodiesel from soybean oil. The present study also evaluated the effects of methanol/oil ratio, catalyst amount, and reaction time on conversion. The catalytic activity of solid base catalysts was insensitive to exposure to air prior to use in the transesterification reaction. Results from ICP-OES exhibited non-significant leaching of the Li₂CO₃ active species into the reaction medium, and reusability of the catalyst was tested successfully in ten subsequent cycles. Free fatty acid in the feedstock for biodiesel production should not be higher than 0.12 % to afford a product that passes the EN biodiesel standard. Product quality, ester content, free glycerol, total glycerol, density, flash point, sulfur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value fulfilled ASTM and EN standards. Commercially available Li₂CO₃ is suitable for direct use in biodiesel production without further drying or thermal pretreatment, avoiding the usual solid catalyst need for activation at high temperature.     

Use of an Adsorption Process for Purification of Pollock-Oil-Based Biodiesel Comprises Methyl Esters

The quality of biodiesel from crude pollock oil and the effect of a purification process on the physicochemical properties of pollock oil biodiesel were evaluated. Unpurified pollock oil (PO) was transesterified to biodiesel from pollock oil (BPO) using methyl alcohol (1:6 molar ratio) and NaOH (1 % w/w of the oil weight); and the resulting fatty acids methyl esters (FAME) were purified with 10 % (w/w) activated earth to yield purified biodiesel from pollock oil (PBPO). The samples were evaluated for yield, FAME composition, free fatty acids (FFA), peroxides value (PV), moisture, bulk density, cloud point, flash point, free and total glycerin, color, rheological properties, and minerals. BPO and PBPO were evaluated for the kinetics of lipid oxidation. The transesterification and purification processes had no effect on the FAME composition of PO. The yield of PBPO was significantly (P < 0.05) reduced after the transesterification and purification processes. Moreover, the transesterification process significantly (P < 0.05) reduced the FFA, moisture, bulk density, flash point, total glycerides, redness, viscosity, arsenic and silicon content in PO. Meanwhile, the purification process significantly (P < 0.05) reduced the PV, redness, and sulfur content of BPO. The flash point of BPO was significantly (P < 0.05) increased by the purification process from 79 to 84 °C. PO, BPO, and PBPO behaved as non-Newtonian and Newtonian fluids at 0 and 25 °C, respectively. BPO showed a lower oxidation rate and activation energy compared to those of PBPO. BPO and PBPO met the ASTM biodiesel standard D6751 for moisture, bulk density, cloud point, free and total glycerin, Na, P, and S. The study demonstrated that high viscosity crude pollock oil could be converted into low viscosity purified pollock oil biodiesel.     

Two approaches in preparation for cogeneration α‐tocopherol and biodiesel from cottonseed

A two‐step process and a direct alkaline transesterification process in preparation for cogeneration α‐tocopherol and biodiesel (fatty acid methyl esters, FAME) from cottonseeds were studied in this article. The effects of some factors on recovery of α‐tocopherol and conversion of cottonseed oil (triacylglycerols, TAGs) to biodiesel in the two processes were systematically studied by single factor experiments and orthogonal design method. In the two‐step process, α‐tocopherol and biodiesel were produced from extraction with two‐phase solvent followed by base‐catalysed transesterification. Approximately 95.5% TAGs was converted into biodiesel, and 1.008 mg/g (wet basis) α‐tocopherol was detected on the condition: 1:3 petroleum ether/methanol volume rate, 40°C extraction temperature; 7:1 methanol/cottonseed oil molar ratio, 1.1% KOH (w/v) concentration in methanol and 60°C esterification temperature. And in the direct alkaline transesterification reaction, 98.3% conversion of TAGs and 0.986 mg/g content of α‐tocopherol could be achieved at 60°C in 2 h. Both of the two processes were feasible from the economic point of view for further utilisation of cottonseed. © 2011 Canadian Society for Chemical Engineering     

Effects of Different Oil Sources and Residues on Biomass and Metabolite Production by Yarrowia lipolytica YB 423-12

Yarrowia lipolytica is known to have the ability to assimilate hydrophobic substrates like triglycerides, fats, and oils, and to produce single-cell oils, lipases, and organic acids. The aim of the present study was to investigate the effects of different oil sources (borage, canola, sesame, Echium, and trout oils) and oil industry residues (olive pomace oil, hazelnut oil press cake, and sunflower seed oil cake) on the growth, lipid accumulation, and lipase and citric acid production by Y. lipolytica YB 423-12. The maximum biomass and lipid accumulation were observed with linseed oil. Among the tested oil sources and oil industry residues, hazelnut oil press cake was the best medium for lipase production. The Y. lipolytica YB 423-12 strain produced 12.32 ± 1.54 U/mL (lipase activity) of lipase on hazelnut oil press cake medium supplemented with glucose. The best substrate for citric acid production was found to be borage oil, with an output of 5.34 ± 0.94 g/L. The biotechnological production of valuable metabolites such as single-cell oil, lipase, and citric acid could be achieved by using these wastes and low-cost substrates with this strain. Furthermore, the cost of the bio-process could also be significantly reduced by the utilization of various low-cost raw materials, residues, wastes, and renewable resources as substrates for this yeast.     

Study on Streptomycin Sulfate Recovery by Batch Foam Separation

The feasibility of foam separation as a technique was assessed for the recovery of streptomycin sulfate from the waste solution by using an anionic surfactant sodium dodecyl sulfate (SDS). The experimental parameters examined were SDS concentration, superficial gas velocity, initial pH, and liquid loading volume. The results showed that sodium dodecyl sulfate as the surfactant for foam separation had good foaming quality and could effectively concentrate streptomycin sulfate of the aqueous solution by technology of foam separation. The enrichment ratio and the recovery rate of streptomycin sulfate were 4.0 and 85%, respectively under the best operating conditions of sodium dodecyl sulfate concentration 0.4 g/L, superficial gas velocity 300 mL/min, liquid loading volume 300 mL and initial pH 6.0 when streptomycin sulfate concentration was 0.5 g/L.     

Implementing an In Situ Alkaline Transesterification Method for Canola Biodiesel Quality Screening

Increasing demand for canola (Brassica napus) as an edible oil crop and biodiesel (B100) feedstock has encouraged genetic development for increased oil yields and expanded acreage in the US Northern Plains. Crop production environment and plant genetics influence metabolism and fatty acid composition, but the influence of this interaction on the resulting fatty acid methyl esters (FAME) is not clearly understood. The objective of this study was to develop a canola in situ transesterification (TE) method for facilitating the identification of genetic, abiotic or biotic factors impacting B100 quality, and to evaluate FAME quality properties from conventional TE (degummed oil) and in situ TE methods. In situ reactions containing 40 g canola flour conducted for 6 h at 60 °C with a 275:1:1.05 M ratio of methanol:triacylglycerol (TAG):KOH provided 80% conversion of seed lipid to FAME. Replicated reactions provided sufficient FAME volume for measuring several ASTM D6751-09 standards including cloud point, kinematic viscosity, acid value, moisture content, oxidative stability, and total glycerin, but adjustments are necessary to provide sufficient volumes for routine analysis of cold soak filtration test. The established in situ protocol would permit weekly analysis of 40 samples and the in situ TE method provides an opportunity to evaluate the impact of genetic or environmental factors on B100 quality.     

Biodiesel production from mixtures of canola oil and used cooking oil

Used cooking oil (UCO) was mixed with canola oil at various ratios in order to make use of used cooking oil for production of biodiesel and also lower the cost of biodiesel production. Methyl and ethyl esters were prepared by means of KOH-catalyzed transesterification from the mixtures of both the oils. Water content, acid value and viscosity of most esters met ASTM standard except for ethyl esters prepared from used cooking oil. Canola oil content of at least 60% in the used cooking oil/canola oil feedstock is required in order to produce ethyl ester satisfying ASTM specifications. Although ethanolysis was proved to be more challenging, ethyl esters showed reduced crystallization temperature (−45.0 to −54.4 °C) as compared to methyl esters (−35.3 to −43.0 °C). A somewhat better low-temperature property of ester was observed at higher used cooking oil to canola oil ratio in spite of similar fatty acid compositions of both oils.