Solvent cooking of cottonseed meats for extraction

Data have been presented for a solvent-cooking method of preparing cottonseed meats for extraction. The study includes experiments in which the flake moisture contents were increased to as high as 40% during the initial solvent cooking phase and decreased to about 10% by the end of the cooking cycle, and in which hexane and heptane were used as the cooking solvent in the presence of chemicals such as NaOH, NaCl, CaCl₂, and NH₃. Results showed specific trends with varying condiditions. Examples are: increase in the initial moisture content during cooking increases granulation and consequently the mass velocity; increase to 30% moisture content is sufficient to result in mass velocities above the desirable 2,000 lbs. per square foot per hour; free gossypol content of the extracted meals is lower with the higher initial cooking moisture contents and with the addition of certain chemicals (NaOH-CaCl₂) ; and the addition of the combination of NaOH and NaCl resulted in better overall filtration-extraction characteristics than either the NaOH-CaCl₂ or the NH₃-NaCl combinations. On the basis of the above results the following general conclusions can be made:

1. Solvent cooking offers the possibility of combining cooking, crisping, and slurrying (extraction) steps into a single operation in a process, such as filtration extraction for the direct solvent extraction of cottonseed.
2. Chemicals can be introduced as needed to promote free gossypol reduction and possibly maintain a high alkali protein solubility in the solvent extracted meal.
3. Agglomeration and extractability of the solvent-cooked cottonseed meats can be controlled.

     

Crambe seed processing: Filtration-extraction on a bench scale

Crambe abyssinica is a potential source of erucic fatty acid and of good quality protein, provided satisfactory methods for processing the seed can be developed. Among the oil recovery methods currently under study is that of filtration-extraction, a direct solvent process for high-oil content seeds. Good oil recovery at satisfactory filtration rates was accomplished by a series of processing steps including dehulling, flaking, cooking, drying, crisping and extracting with hexane. When the conventional cook procedure was modified to incorporate an enzyme-conversion step, significant improvement in rat feeding tests was obtained without loss in subsequent extraction efficiency. The recovered oils from the nonconversion cooks were refined and bleached by conventional procedures to oils of light color. The oil product from the conversion cook apparently contained sulfur compounds, even after refining and bleaching, whose removal will require special treatment as yet undeveloped in order to produce a hydrogenatable oil. Presented in part at AOCS Meeting, New Orleans, 1964. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Present status of the filtration-extraction process for cottonseed

Summary Improvements and refinements in the process for filtration-extraction of cottonseed resulting from further pilot-plant development studies are described as well as their adaptation to the first commercial plant. These improvements which depict the present status of the process for cottonseed include principally certain modifications in the method of conditioning of the meats or flakes prior to cooking and in the procedure for crisping; selection of best conveyor type for conveying cooked material over relatively long distances without objectionable comminution; selection of filter medium combining the desired properties of durability, non-fouling, and low fines retention; determination of optimum filter-cake thickness; and development of a method for clarification of the product miscella by continuous recycling through the formed cake on the filter. Also discussed is the quality and color stability of the oil produced from comparable lots of cottonseed by the filtration-extraction process, as compared with that by hydraulic pressing, and by solvent extraction of uncooked flakes. Presented at the 45th annual meeting of the American Oil Chemists' Society, San Antonio, Tex., April 11–14, 1954. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Direct extraction of jojoba seed

Summary Data for the application of the versatile filtration-extraction process to jojoba seed on a bench-scale has been presented. Based on experience with other oil-seeds, there should be good correlation between the bench-scale and its commercial application. Moisture contents of the material during cooking were optimum at 10 and 15%. Mass velocities in excess of 2,000 and extraction efficiencies of over 98% were obtained. These results are considered suitable for commercial application. Hexane is recommended over heptane as the extraction solvent. The use of uncooked flakes is not considered feasible for large-scale application. Presented at the Fall Meeting, American Oil Chemists’ Society, Los Angeles, Calif., September 28–30, 1959. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Direct extraction of sunflower seed by filtration-extraction

Conclusions The influence of certain variables upon the direct, continuous, solvent extraction of sunflower seed meats has been discussed. It has been shown that the ideal preparation consisted of first reducing the hull content to about 10% by weight. Then the dehulled meats were rolled, cooked, crisped, and re-rolled prior to solvent extraction. Drying before rolling, followed by cooking and crisping, was also helpful in the reduction of residual lipids content but to a lesser degree than was re-rolling after cooking. It has been shown that the use of relatively low solvent/meats ratios required initially high mass velocities and that mass velocity during extraction was higher than that realized during cake washing. The full industrial-scale run confirmed the experimental findings; thus the direct, continuous, solvent extraction of sunflower seed meats is a commercial reality. An oil-content reduction from 53% to 1.68% in one operation is a technological advance of great magnitude. Except for periods when rice bran is processed, the plant is in continuous operation on sunflower seed meats and consistently produces meals containing between 1.5% and 1.7% oil content.     

Screw pressing of whole and dehulled flaxseed for organic oil

Flaxseed oil, a rich source of dietary n−3 FA, is commonly obtained by cold pressing whole seed. Furthermore, flaxseed hulls are emerging as a valuable lignan-rich product for functional food use; therefore, the pressing characteristics of dehulled seed need to be understood. Screw press performance was measured for pressing of whole and dehulled flaxseed. When whole Omega flaxseed was pressed through a 6-mm choke, an inverse relationship between seed moisture content (6.1–11.6% range) and oil recovery (70.1–85.7%) was observed. However, peak oil recovery from pressing dehulled Omega flaxseed of 72.0% was found at 10.5% moisture content in the moisture content range of 7.7–11.2%. Although oil recovery from dehulled Omega flaxseed was lower than from whole Omega flaxseed, the weight of oil produced from dehulled Omega flaxseed per unit time was higher. The dependence of capacity on moisture content was less evident with the 6-mm choke than with the 8-mm choke. An inverse relationship between moisture content of whole flaxseed and oil and meal temperature was observed. The oil and meal temperatures from pressing dehulled flaxseed were significantly lower than those from whole flaxseed. Therefore, pressing dehulled flaxseed appears to offer advantages in organic flaxseed oil production.     

Extraction of oil from meadowfoam flakes

As part of a program to improve meadowfoam seed processing, the authors examined the effects of seed moisture, seed temperature, and flaking roll opening on oil extraction efficiency in meadowfoam flakes. Flakes were prepared using a Wolf Mill with dual horizontal, unheated 12-in. diameter rolls. Roll openings of 0.005, 0.013, and 0.020 in. (0.127, 0.330, and 0.508 mm, respectively) gave average flake thicknesses of 0.013, 0.021, and 0.031 in., respectively (0.330, 0.533, and 0.787 mm). Seed moistures of 9, 12, and 15% and seed temperatures of 65, 190, and 210°F (18, 88, and 99°C) chosen for flaking were known to provide a range of conditions suitable for enzyme inactivation during seed cooking prior to flaking. Experimental flakes were examined for extractable oil content (petroleum ether extraction); this was compared to total oil content (31.5%) determined on finely ground flakes. Roll opening was the dominant variable determining flake thickness, the primary parameter affecting oil extraction efficiency. Thus, the thinnest flakes at 0.013 in. were only slightly less extractable (29.8%) than finely ground flakes (31.5%), but intermediate (0.021 in.) and thick (0.031 in.) flakes were significantly less extractable (28.0 and 26.0%, respectively). There was a slight but significant (P<0.01) trend toward thicker flakes with increasing seed moisture (15>12>9%) during flaking. A similar trend to thicker flakes with increasing temperature was significant (P<0.01) only for the thickest flakes produced at the largest roll opening (0.020 in.). Lower seed moisture and higher seed temperature significantly impacted extractable oil content of the thickest flakes, but negligibly affected extractability of the thinnest flakes. The authors conclude that meadowfoam flakes must be as thin as possible (e.g., <0.015 in.) for efficient oil extraction. Further, seed cooking temperatures >190°F at moistures >10% and <15% that are adequate for efficient enzyme inactivation in the whole seed are also suitable for seed flaking.     

Pilot plant development of the alkali cooking process for cottonseed meats. I. Effect of flake,thickness and of time,temperature, and moisture content during cooking

Summary and Conclusions Results obtained from alkaline cooking experiments show that all of the four variables studied—cooking mousture content, temperature, time and flake thickness—influenced the properties of the resultant meals in varying degrees. Under the experimental conditions used a high initial moisture content, above 18%, is necessary to lower the free gossypol content in the finished meal to less than 0.04%. When this amount of moisture is used, a plastic mass results at the beginning of the process which requires special equipment to supply the mechanical action necessary to break the pigment glands at a low temperature. In the presence of high moisture content and alkali the gossypol, which is released when the glands are ruptured, is bound to the meal. When sufficient initial moisture is present (24–31%), only traces of gossypol (0.010% or less) are found in the extracted crude oil. High temperatures in the presence of high moisture content reduce the solubility of the meal protein (in 0.02N NaOH). Under the conditions of moisture, temperature, and time of cooking used in the experiments the maximum nitrogen solubility obtained under conditions necessary to produce low free gossypol content was 64%. This differs from results obtained in previous work performed under different conditions. A probable reason for the difference is given based on the interrelationship of the three variables. The results demonstrated further that finer comminution of the raw meats by rolling to 0.005-in. thick flakes results in lower free gossypol content in the finished meal and lower gossypol content of the oils as well as more complete removal of the oil by the filtration-extraction procedure used. One of the laboratories of the Southern Utilization Research Branch. Agricultural Research Service, U. S. Department of Agriculture.     

Effect of flaxseed processing on engineering properties and fatty acids profiles of pasta

Flaxseed contains numerous bioactive compounds which induce various biological effects. Among bioactive compounds, flaxseed contains 38–45% oil, of which up to 59% is α-linolenic acid. Focus has recently been put on the technical difficulties of processing flaxseed pasta and studies have shown that flaxseed could tolerate some processing conditions. A close link between pasta processing conditions and the in vitro digestion of the food matrix has also been identified. The aim of this study were (1) to understand the impact of flaxseed processing and content on engineering properties of pasta after the extrusion, the drying and the cooking process; (2) to characterize the fatty acids profile of flaxseed-enriched pasta during the processing and after the in vitro digestion. Two processes were considered prior to the incorporation of flaxseed into pasta at levels of 15% and 30% (dry basis): (Process A) conditioning and milling of flaxseed; (Process B) conditioning of flaxseed, oil pressing, milling of flaxseed cake and reformulation. Results showed that pressing oil from flaxseed and then milling the flaxseed cake (Process B) allowed obtaining an average particle size smaller than milling the whole flaxseed (Process A) which doubled the flaxseed-to-semolina particles ratio. Flaxseed processing, prior to the incorporation into pasta, and content had impacts on engineering properties after the extrusion, the drying and the cooking process and, affected the protection and the release of free fatty acids during in vitro digestion. While free fatty acids profiles remained relatively stable through all steps of pasta processing, they were affected by the in vitro digestion. Decrease in the proportion of omega-3 fatty acid (C18:3) was more important for the Process A compared to the Process B.     

Cottonseed preparation

Conventional methods of cottonseed preparation are reviewed and described, including seed cleaning, saw delinting, dehulling, conditioning, and flaking. The use of screw presses for prepress conditioning ahead of solvent extraction is discussed as compared to conditioning for direct solvent extraction. Newer methods and proposed alternate methods of cottonseed preparation are discussed including: abrasive delinting, acid delinting by gas and liquid acid, and the decorticating of undelinted seed. The effect of cracking rolls, moisture addition, moist cooking and flaking on gossypol gland rupture, the binding of gossypol to protein, and the effect of these processing or preparation variables on the residual oil in the extracted meal and on the oil quality are discussed.     

Effects of different drying methods on the extraction rate and qualities of oils from demucilaged flaxseed

Effects of different drying methods, i.e., oven drying, freeze drying, vacuum drying, and microwave drying, on the extraction rate and qualities of oil extracted from demucilaged flaxseed were investigated. The results show that microwave drying and freeze drying have higher extraction rate and yield (46.36 and 46.16% vs. 33.90%) of oil compared with native flaxseed. The oil extracted from dried flaxseed, especially the one freeze dried, had higher peroxide value (21.63 vs. 6.15?meq/kg) and specific ultraviolet extinction at 232?nm (4.56 vs. 3.67) and 268?nm (1.23 vs. 1.12), as well as a shorter induction time (1.8 vs. 3.3?h) than the one from native sample. Demucilaging and drying have no significant effect on fatty acid composition of flaxseed oil. However, these processes increased the content of total phenols and total sterols while reduced the content of chlorophyll and carotenoid pigment. In addition, the oil extracted from vacuum dried flaxseed contained more tocols when compared with native sample (447.29 vs. 370.99?mg/kg).     

Factors affecting the pressure extraction of oil from flaxseed

The effects of moisture content, age, growing location, and genotype of flaxseed on the efficiency of pressure extraction of oil, when extracted in a Carver press cylinder, were examined. Decreasing the seed moisture content from 7.8% to 2.3% increased the proportion of oil extracted from 31.4% to 49.6%, respectively. Oil was more difficult to extract as the age of the seed increased. The proportion of the total oil extracted varied from 25.0% to 41.4% depending upon the location where the seed was grown. The effect of genotype was less pronounced, ranging from a mean of 46.9% in Redwing to 54.2% in Redwood 65 for samples analyzed at normal storage moisture. Samples with high oil contents usually yielded the highest proportion of total oil recovered (r=0.893^**, 9 df). Contribution No. 153, Morden Research Station.     

Effect of moisture and temperature on the phosphorus content of crude soybean oil extracted from fine flour

Analysis of total oil content in soybeans is usually done by extracting flours, whereas commercial extraction for recovery of oil is done by extracting flakes. It has recently become apparent that phosphorus content of crude soybean oil extracted from flours can vary depending on extraction temperature and flour moisture. In this study, flour moistures below 6% yielded crude oil with low phosphorus (15 ppm), but phosphorus in the oil increased rapidly to 260 ppm at 9% moisture. When temperature of the extraction was increased from 25 to 60°C, the phosphorus in extracted oil also increased for moisture contents of 6.6% and 8.3%, but not for moisture contents of 5% and 3%. In addition to the effects of extraction temperature, it was found that preheating whole soybeans at various temperatures affected phosphorus in oil from extracted flour. Preheating at 130°C caused high phosphorus content regardless of how dry the flour was, whereas preheating at 100°C or below caused phosphorus content that increased with increased moisture. The response of phosphorus content in crude oil to temperature and moisture may be useful in improving the quality of commercially extracted soy oil.     

Effect of Various Pressure Cooking Conditions on Gossypol Content of Cottonseed Meal and Oil

Egyptian cottonseed meats were obtained from one of the largest Egyptian factories dealt with oil production in Egypt. Studies were carried out to demonstrate the favorable conditions for cooking meats to produce oil and meal low or even free of gossypol. Cottonseed meats were conditioned to four different levels of moisture and cooked at three different levels of pressure for two different cooking periods. The decrease (91.1%) of the free gossypol content in the meals depended mainly upon the moisture content of the conditioned meats and the cooking temperature rather than on the cooking period. While the decrease (96.5%) of the total gossypol content of oil was more pronounced by the increment of both the cooking period and the level of moisture content to which the meat was conditioned. Generally, moist pressure cooking decreased the protein content of meats by 8% and the free fatty acids of oil were decreased to 1.12–1.18%. Laboratory produced meats and oils were compared with those produced in the factory.     

The influence of moisture content and cooking on the screw pressing and prepressing of corn oil from corn germ

Samples of corn germ were obtained from a commercial corn wet mill (factory dried to about 3% moisture) and a commerical corn dry mill (undried, produced in the mill with about 13% moisture). The germ samples (200 g each) were cooked for various times in either a conventional oven at 180°C or a microwave oven at 1500 W. Bench-scale single screw pressing was then performed. With the dry milled corn germ, no oil was obtained from the uncooked germ. A maximal yield of about 5% oil [26% of total oil recovery (TOR), relative to hexane extraction] was obtained by cooking the dry-milled germ for 6.5 min in a conventional oven at 180°C before pressing. A maximal yield of about 7% oil (37% TOR) was obtained by cooking the dry-milled germ for 4.5 min in a microwave oven at 1500 W before pressing. With the wet-milled germ, yields of about 7% oil (18% TOR) were obtained with the uncooked germ and yields increased to a maximum of about 22% oil (56% TOR) by cooking in a conventional oven at 180°C for 5 min or a maximum of about 17% oil (44% TOR) by cooking for 4 min in a microwave oven at 1500 W. These results indicate that microwave and conventional oven cooking are both effective pretreatments before pressing. Microwave preheating resulted in higher oil yields with dry-milled germ, and conventional oven pretreatment resulted in higher oil yields with factory-dried wet-milled corn germ.     

Comparative absolute yields of crude and neutral oils from variously prepared cottonseed meats

Summary Experiments utilizing cottonseed meats of diverse origin and composition were conducted for the purpose of determining the effect of the method of meats preparation on the yields of crude and neutral oil obtainable from differently prepared, comparable meats by solvent extraction. Three methods of meats preparation were employed,i. e., simple flaking of raw meats “as is”, tempering of cracked meats prior to flaking, and cooking by the modified hydraulic method developed for use with the filtration-extraction process. Commercial hexane was used as the extraction solvent. The experiments were carried out by procedures which eliminated the effects of any variables other than the method of preparing the meats for extraction The results of the studies showed that the method used in preparing cottonseed meats for extraction had a significant effect on the yields of crude oil obtained but that the yields of neutral oil, the valuable constituent of crude oils, were virtually unaffected. Analyses of the crude oils showed that the differences in crude oil yields were caused by the relative amounts of non-neutral oil materials in the crudes from the differently prepared meats. The greatest yields of crude oil were obtained from raw flakes, intermediate yields from tempered flakes, and the smallest yields from cooked flakes. The impurities content in the respective crude oils followed the same order,i. e., crudes from raw flakes were highest in impurities and lowest in neutral oil, crudes from tempered flakes were lower in impurities and higher in neutral oil, and the crudes from the cooked meats were outstandingly low in impurities and high in neutral oil. Virtually equal amounts of neutral oil were obtained from equivalent quantities of comparable meats regardless of the method used in preparing the meats for extraction. Presented at the meeting of the American Oil Chemists’ Society, Chicago, Ill., September 24–26, 1956. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U.S. Department of Agriculture.     

Supercritical CO2 extraction of flaxseed

Extraction of flaxseed oil was performed with supercritical carbon dioxide (SC-CO₂). To investigate the effects of pressure and temperature on the solubility of oil and oil yield, three isobaric (21, 35, and 55 MPa) and two isothermal (50 and 70°C) extraction conditions were selected. Although the maximal solubility of flaxseed oil, 11.3 mg oil/g CO₂, was obtained at 70°C/55 MPa, the oil yield obtained after 3 h of extraction at this condition was only 25% (g oil/g seed×100), which represented 66% of the total available oil of the flaxseed. Lipid composition and FFA and tocol (tocopherol and tocotrienol) contents of the oils obtained by both SC-CO₂ and petroleum ether extraction were determined. The α-linolenic acid content of the SC-CO₂-extracted oil was higher than that obtained by solvent extraction.     

Simultaneous recovery of wax and oil from rice bran by filtration-extraction

Summary Hard rice waxes of high melting points have been obtained directly from rice bran while simultaneously producing oil. These waxes were produced by the following two methods. 1. selective cold hexane-extraction of cooked rice bran to remove the oil, hot hexane-extraction to remove the wax, chilling of the hot miscella and separation of the precipitated wax by centrifugation; 2. single hot hexane-extraction of raw or cooked rice bran, hot water washing and chilling of the miscella, separation of the wax precipitate by settling or centrifugation, and multiple cold hexane-washings of the wax. Wax can also be processed from rice oil settlings by the latter method after a miscella has been prepared. The cold extraction-hot extraction method should be preferable as a process when conducted on a single continuous filtration-extraction unit without reslurrying. Indications are that oil refining losses may be decreased by this method. Yields of rice wax varied from 0.22 to 0.31% of the original rice bran, or 1.29 to 1.82% of the extracted oil. Presented at the annual fall meeting, American Oil Chemists’ Society, Nov. 2–4, 1953, Chicago, Ill. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, United States Department of Agriculture.     

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.     

Pilot plant extraction of oil fromVernonia galamensis seed

Vernonia galamensis seed containing 40–42% oil and 30–34% epoxy acid, (cis-12,13-epoxy-cis-9-octadecenoic) was processed to oil and meal. Seed conditioning, pressing and solvent extraction research were conducted in pilot facilities at the French Oil Mill Machinery Co. (Piqua, OH). The robust lipase system was successfully inactivated by treating 200 lb. batches ofV. galamensis seed in a cooker/conditioner at 195–200°F and >10% moisture. Conditioned seed was mechanically pressed and the press discharge cone setting was varied during operation from 1/32″ to 3/32″ to demonstrate the feasibility of both full pressing and prepressing. Prepressing successfully reduced oil level in the press cake to ca. 20%. Press cake was extracted with hexane in a 1.5-ft³ batch-type, four-stage percolation unit with a 6″ square extraction cross section. Solvent extraction reduced oil level in the defatted meal to 1–2%. The defatted meal was desolventized and toasted. Excessive foaming of the vernonia oil extract made complete solvent stripping in the oil stripping unit difficult.