Phase relations pertaining to the solvent winterization of cottonseed and peanut oils in acetone

Summary and Conclusions Systematic physical chemical data on the solventwinterization behavior of cottonseed and peanut oils with acetone have been obtained which should serve as a basis for selecting the conditions necessary for the effective solvent winterization of these oils in acetone. Cottonseed and peanut oils are only partially miscible with acetone below certain temperatures which have been determined. In peanut oil this phenomenon may interfere with the winterization process within a certain range of concentrations. For cottonseed oil however the separation into two liquid phases does not occur until some 5°C. below the temperature required for adequate winterization. Complete data for a 3-hour holding-time have been obtained for three cottonseed oils ranging in iodine value from 106.1 to 116.4. Tables and graphs have been constructed to show the effect of oil-solvent ratio, chilling temperature, holding-time, agitation, and iodine value of the original oil on the percentage of solid removed and on the degree of winterization and iodine value of the winterized oil. Similar data have been obtained for a refined peanut oil insofar as possible without interference from separation into two liquid phases. It seems probable that if acetone were used as the winterization solvent for peanut oil, the separation into two liquid layers and the sensitivity of this phenomenon to moisture might be a source of processing difficulties especially if filtration instead of centrifugation were used to separate the solid from the supernatant. Resigned: September 2, 1949. Resigned: August 13, 1948. Resigned: January 28, 1949. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Spectrophotometric estimation of soybean oil in admixture with cottonseed and peanut oils

Conclusion A spectrophotometric method has been described for the determination of soybean oil in admixture with cottonseed oil. The method provides a simple and rapid means of detecting gross adulteration of one oil with another and permits an accurate determination of linolenic acid for use as a criterion of the economic value of an oil mixture and as a guide in oil processing. The factor limiting the precision of the method is variation in composition of the cottonseed and soybean oils in the mixtures to be analyzed. Variations in composition affect the proportion of measured triene conjugation, due to the linolenic acid content of the soybean oil and the apparent linolenic acid content of the cottonseed oil. Thus, for unknown mixtures only average value corrections can be made for apparent linolenic acid content and the accuracy of a particular analysis will depend upon how well the composition of the oils in the particular mixture follows those of the average mixture. The method described can be extended to mixtures other than those of soybean and cottonseed oils. Thus, soybean oil may be determined in admixture with a peanut oil. In general, any oil which has an unsaturated fatty acid capable of producing triene conjugation upon alkali isomerization can be determined in the presence of any other oil containing no appreciable quantity of unsaturated fatty acids which can produce triene conjugation by such treatment. Presented before The American Oil Chemists’ Society, New Orleans, Louisiana, May 10–12, 1944. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Enzyme-assisted aqueous extraction of peanut oil

Enzyme-assisted aqueous extraction of oil from oilseeds is a relatively recent technique. In the present study, peanut oil was extracted under optimized aqueous extraction conditions using Protizyme^™, which is predominantly a mixture of acid, neutral, and alkaline proteases. The optimal conditions were: enzyme concentration of 2.5% (w/w) in 10 g of peanut seeds, pH 4.0, 40°C, and 18 h incubation with constant shaking at 80 rpm. Centrifuging the mixture at 18,000 × g for 20 min separated the oil with a recovery of 86–92%. The merits of this process over existing solvent extraction and/or mechanical pressing methods are discussed.     

Dilatometric investigations of fats II. Dilatometric behavior of some plastic fats between 0° C. and their melting points

Summary 1. Dilatometric curves between 0°C. and their melting points have been obtained for the following fats: lard, butterfat, cottonseed oil, peanut oil, a commercial margarine oil, a commercial all-hydrogenated vegetable shortening, three samples of soybean oil hydrogenated to different degrees, a hard butter fractionally crystallized from hydrogenated peanut oil, a mixture of tristearin and soybean oil, and a synthetic fat containing equal molar proportions of stearic and oleic acids. 2. The dilatometric curves, of volume change in the fat against temperature, were in every case composed of a series of straight lines, separated by sharp breaks or transition points. 3. The number of linear sections in the dilatometric curves corresponded in a general way with the known degree of complexity in the glycerides of the fats, and varied from two in the case of the relatively simple stearic-oleic glyceride mixture, to at least seven in the case of the all-hydrogenated shortening. Since each break in the curve must correspond to the disappearance of a distinct class of solid glycerides or glyceride complexes, the application of dilatometry to the qualitative and quantitative determination of glyceride composition in fats is suggested. 4. Only two of the fats examined, the mixture of tristearin and soybean oil, and the synthetic stearicoleic glyceride mixture, exhibited polymorphism, even after rapid solidification in ice water. Presented before the American Oil Chemists’ Society Meeting, New Orleans, Louisiana, May 10 to 12, 1944. This is one of four regional research laboratories operated by the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Possibilities of peanut,pecan and safflower seed oils as supplements for olive oil

Summary Samples of completely refined peanut oil, semirefined pecan oil, imported edible grade olive oil and crude safflower seed oil have been examined for composition, spectral transmittance and other properties. Compositions were determined by means of the modified Bertram oxidation method and application of the iodine-thiocyanogen number technique. None of the oils examined simulate olive oil in composition. Peanut and pecan oils appear capable of modification to produce a product chemically similar to olive oil and for certain purposes can replace olive oil without modification. The production of pecan oil under present market conditions with regard to prices for edible oils and seedling pecan nuts does not appear to be very attractive unless the costs of processing pecans for oil can be greatly reduced. Presented before the American Oil Chemists’ Society Meeting, Houston, Texas, April 30 to May 1, 1942.     

Phase relations pertaining to the solvent winterization of crude peanut oil in 85-15 Acetone-hexane mixture

Fundamental phase relation data have been obtained on a laboratory scale which show that solvent winterization of crude peanut oil is feasible in a solvent consisting of 85 parts by weight of acetone and 15 parts of commercial hexane. The results show the effect of oil-solvent ratio, chilling temperature, and holding-time upon the percentage of solid removed. The behavior of crude peanut oil is very similar to that of the refined oil in the same solvent except that a slightly lower chilling temperature is required and that the crystals tend to form a little more slowly and do not settle out as readily. The advantage of winterizing hexane-extracted peanut oils before refining is discussed.     

Water-in-triglyceride oil emulsions. Effect of fat crystals on stability

The influence of low concentrations (0.1-5%) of fat crystals on the stability of water-in-soybean oil emulsions was examined by light scattering and sedimentation experiments. Both the initial flocculation/coalescence rate and long-term stability against water separation were determined. The initial flocculation/coalescence rate increased upon addition of small amounts of fat crystals. When the crystal concentration was increased above a critical concentration (specific to a system), a decrease in the flocculation/coalescence rate occurred. The increased flocculation/coalescence rate is likely the effect of bridging of water droplets by fat crystals. Fat crystal wetting by water is an important criterion for this phenomenon to occur. Emulsion stabilization for crystal concentrations above critical is caused by a mechanical screening of water droplets. The presence of considerable amounts of crystals in oil also lowered the density difference between droplet and medium, and enhanced viscosity. The degree of increase in viscosity depended upon the emulsifier. Both a decrease in density difference and an increase in viscosity play a role in hindering flocculation/coalescence of droplets. In long-term studies of water separation, all concentrations of fat crystals stabilized the water-in-oil emulsions. The droplet size of these emulsions increased until the critical droplet size was approached where the screening effect of crystals on the droplets no longer stabilized the emulsions. The stabilizing effect for emulsions with monoolein was continuously improved by increasing the amount of crystals up to 5%. For lecithin-stabilized emulsions, an optimal effect was achieved for fact crystal concentrations of 1–2%.     

Changes in carotenoid and oil content during maturation of peanut seeds

To understand the changes in the color of peanut oil during maturation of the seeds, measurements were made of carotenoid and oil contents per kernel and carotenoid concentration of extracted peanut oil between the 4th and 12th weeks from pegging. Initially carotenoid concentration in the oil declined rapidly followed by a 50% decline between the 6th and 12th week. Changes in the carotenoid content and oil content of the peanut kernel indicated that the decrease in carotenoid concentration was due to a dilution produced by the rapid increase in oil content. Evidence is presented to indicate that the carotenoids are in areas separated from the oil containing spherosomes of the peanut kernel. Paper number 2872 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, N.C. MQRD. ARS, USDA. SURDD, ARS, USDA. North Carolina State University, Raleigh, N.C.     

Aqueous enzymatic extraction of peanut oil and protein hydrolysates

The aqueous enzymatic process of simultaneously preparing oil and protein hydrolysates from peanut was investigated. The optimum parameters for hydrolysis using Alcalase 2.4L were established by the single-factor and orthogonal test. The optimal processing conditions were as follows: hydrolysis temperature 60 °C, pH 9.5, ratio of material to water 1:5 (w/w), alkaline extraction time 90 min, enzyme amount 1.5% (w/w) and hydrolysis time 5 h. Under these conditions, the free oil and protein hydrolysates yields were 79.32% and 71.38% respectively. In order to improve these yields, As1398 was chosen to hydrolyze the residue and emulsion. The total free oil and protein hydrolysates yields were increased to 91.98% and 88.21% respectively.     

Determination of moisture in peanut butter

Summary and Conclusion The moisture and volatile content of whole peanuts has been determined by A.O.C.S. Official Method Ab 2-49 and has been compared with the moisture content of the sliced peanuts determined by a toluene distillation procedure described by Tryon (5). For practical purposes the results obtained by these methods are in agreement. Moisture of peanut butter has been determined by an over loss-in-weight technique corresponding to the conditions of A.O.C.S. Official Method Ab 3-49 for “second” moisture, and by the toluene distillation method. The results indicate that less dehydration was attained by A.O.C.S. Official Method Ab 3-49 than by the toluene distillation procedure. Losses in weight of peanut butter samples have been determined in vacuum and forced-draft ovens at 130° C. No differences were observed which would indicate that the conditions of A.O.C.S. Official Method Ab 3-49 produce low results because of oxidation. It can be concluded that the toluene distillation procedure, using apparatus described by Tryon (5), is suitable for determining the relatively small amounts of moisture present in peanut butter. The unique features of this apparatus seem to make the method particularly adaptable to peanut butter. This information is presented to provide the peanut butter industry with an additional method for use in problems involving determination of small amounts of moisture and for comparison with other prevailing methods. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Effects of dietary peanut oil on serum lipoprotein patterns of rats

Oils prepared from two varieties of peanuts and from a hybrid corn having linoleic acid concentrations substantially different from the respective commercial oils were compared with commercial oils for their effects on serum lipids of weanling female rats. In the first experiment, serum lipid patterns appeared to reflect linoleic acid content of the dietary oil. However, with a longer feeding period in the second experiment, serum lipid patterns were determined by the plant source of the dietary oil rather than its linoleic acid content; all peanut oils differed from both corn oils in their physiological effects. Diets containing triglyceride, hydrocarbon and sterol fractions obtained by liquid chromatography of peanut and corn oils were fed to female rats. The data provide no evidence that the hydrocarbon or sterol fractions of peanut oil are responsible for its unusual atherogenicity when fed as the sole fat source or that similar fractions from corn oil are protective against the effects of peanut oil.     

Key operations in the wet-rendering of peanut for the isolation of protein,oil and starch

Separation of oil and suspended solids from peanut slurry are two important interdependent operations in wet rendering of peanuts. A 3-way centrifuge cannot be used efficiently for the separation of the different phases due to the large volume of fibrous suspended solids in peanut slurry. Removal of suspended solids from the slurry by filtration is too slow and incomplete, as the fine particles tend to block the screen. The alternative method of centrifugal sedimentation of the suspended solids causes emulsification of the oil and results in the inefficient separation of the oil. It is shown in the paper that efficiency of the separation of oil and carbohydrate fraction from peanut by wet rendering method depends on careful conditioning of the seed.     

Effect of composition and polymorphic form on the hardness of fats

Summary Hardness is an important index in the performance of confectionery and other fats. Using an instrument and technique which were essentially a modification of those used in the Brinell test as applied to metals, the effect of composition and polymorphic form on the hardness of fats was investigated. It was found that the hardness of a given sample of fat was influenced by the degree of tempering to which the sample had been subjected. Hardness always increased as the components of a fat were converted to higher-melting polymorphs. However the hardest test specimens were not obtained with the highest tempering temperatures. Presumably the use of too high a temperature in tempering melted some of the lowermelting polymorphs and allowed them to resolidify in larger crystals producing a softer matrix. Adding progressively larger amounts of one fat to another generally increased or decreased the hardness of the mixture in a more or less uniform manner. Adding small amounts of liquid oil to a hard fat greatly decreased the hardness index. Apparently the hardness index of a given fat decreases as the crystal size increases. It is believed that fats containing a sizable proportion of liquid component will become softer on prolonged storage because the presence of the liquid component makes possible a gradual increase in crystal size. Presented at the 50th Annual Meeting, American Oil Chemists' Society, New Orleans, La., April 20–22, 1959. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Extraction of peanut skin oil by modified supercritical carbon dioxide: Empirical modelling and optimization

ABSTRACT

Peanut skin is a waste by-product from peanut industries. It is rich in antioxidants and bioactive compounds. Therefore, the objective of this study was to empirically model and optimize supercritical CO₂ extraction of oil from peanut skin. The extraction conditions were pressure (100, 200 and 300 bar), temperature (313, 328 and 343 K) and rate of modifier ethanol (0.075, 0.15 and 0.225 mL/min). The extraction process was subsequently examined using modified Brunner and Esquivel models. The optimum conditions for extraction peanut skin oil were 279 bar, 70°C and rate of modifier of 7.5% with a maximum yield of peanut skin oil of 0.83 g and initial slope of 0.568 g/min.     

Carotenoid pigments of peanut oil

A method for analysis of carotenoid pigments in peanut oil is described. The major carotenoid pigments found in peanut oil were beta-carotene and lutein. A sample of oil from immature peanuts contained 60 μg of beta-carotene and 138 μg of lutein per liter of oil. The total carotenoid concentration in oil from mature peanuts appears to be less than 1 μg per liter of oil. Contribution from the Departments of Botany and Food Science, North Carolina State Experiment Station, Raleigh, N. C., in cooperation with the US Department of Agriculture, ARS, Market Quality Research Division, and SURDD. Paper No. 2273 of the Journal Series. MQRD, ARS, USDA. SURDD, ARS, USDA.     

Molecular distillation of a hydrogenated cottonseed oil and certain characteristics of the distilled fractions

Summary 1. A hydrogenated cottonseed oil has been molecularly distilled, and the distilled fractions examined. 2. Fractionation of a molecularly distilled oil occurs, as is to be expected, on the basis of variations in molecular weight of the glycerides. The composition of cottonseed oil is such that there is a considerable separation of the glycerides according to their degree of unsaturation. The composition of peanut oil is such that similar separation can only be slight. Soybean oil is in this respect intermediate between cottonseed oil and peanut oil. 3. Molecular distillation of hydrogenated cottonseed oil causes a segregation of tocopherols and related compounds similar to that observed in peanut oil. However, the fractions first distilled from the oil are relatively weak in antioxygenic properties. It appears probable that their lack of effectiveness is due to the presence of unknown substances capable of inhibiting or counteracting the action of tocopherols. However, the presence of substances other than tocopherols, which respond to or interfere with the Emmerie-Engel test is not to be excluded. The tocopherols in the potent fractions are more effective thana-tocopherol, but less effective than γ-tocopherol. This is one of four regional research laboratories operated by the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Biodiesel production via peanut oil extraction using diesel-based reverse-micellar microemulsions

Vegetable oils have been studied as a feasible substitute for diesel fuel, and short term tests using neat vegetable oils have shown results comparable to those of diesel fuel. However, engine problems arise due to the high oil viscosity after long-term usage. Vegetable oil/diesel blending as biodiesel fuel has been shown to be one technique to reduce vegetable oil viscosity. The goal of this research is to demonstrate the feasibility of producing this biodiesel fuel via vegetable oil extraction using diesel-based reverse-micellar microemulsions as an extraction solvent. In this extraction technique, peanut oil is directly extracted into the oil phase of the microemulsion based on the “likes dissolve likes” principle and the product of the extraction process is peanut oil/diesel blend. The results show that diesel-based reverse micellar extract oil from peanuts more effectively than both diesel and hexane alone under the same extraction condition. An extraction efficiency of 95% was achieved at room temperature and short extraction time of 10 min in just a single extraction step. The extracted peanut oil/diesel blend was tested for peanut oil fraction, viscosity, cloud point and pour point, which all meet the requirements for biodiesel fuel.     

Pre-treatment of peanut kernels for effective skin removal

Summary A new method for the removal of skins from peanut kernels by water-treatment, drying, and blanching in a standard split-nut blancher has been developed on a pilot-plant scale. Optimum conditions for approximately 98% skin removal from U. S. No. 1 shelled Spanish peanuts by this method are water-treatment at room temperature, to gain not less than 20%, drying with forced circulated air at 120° to 125°F. to approximately 4.5% moisture in the peanuts, and blanching. The lipids and protein losses resulting from the water-washing action on the kernels were relatively low and less than those losses obtained by lye treatment of the kernels. The method however did not give satisfactory results with either shelled U. S. No. 2 or oil mill stock kernels. Meal prepared by hexane extraction of de-skinned (98%) water-treated U. S. No. 1 kernels had color and flavor characteristics superior to other hexane solvent-extracted peanut meals for food utilization. Protein prepared from this meal had a light color equal to that produced from peanut kernels treated with 0.5% lye solution. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U.S. Department of Agriculture.     

The absorption and transport of dietary cholesterol in the presence of peanut oil or randomized peanut oil

Peanut oil has been shown to be unexpectedly atherogenic for cholesterol-fed rats, rabbits and rhesus monkeys. However, randomization (rearrangement of fatty acids to random distribution) of peanut oil significantly reduced its atherogenicity for rabbits and monkeys. This study was conducted to investigate whether the absorption and transport of dietary cholesterol was altered in the presence of peanut oil or randomized peanut oil, thereby accounting for the difference in the atherogenicity of the two diets. Intestinal lymph fistula rats were infused intraduodenally with a lipid emulsion at a rate of 3 ml/hr. The lipid emulsion contained either peanut oil (control) or randomized peanut oil (experimental) (10 mM),¹⁴C-cholesterol (1.3 mM) and sodium taurocholate (19 mM) in phosphate-buffered saline, pH 6.4. Lymph triglyceride, cholesterol and phospholipid outputs were similar in both groups of rats during fasting and subsequently during lipid infusion. Comparable recovery of¹⁴C-cholesterol from the intestinal lumen and the intestinal mucosa of the control and the experimental rats showed that the absorotion and transport of dietary cholesterol were similar in both groups of rats. Analyses of thefatty acid of both lymph and intestinal mucosal lipid again failed to reveal a difference between the 2 groups of rats. It is concluded that the difference in the atherogenicity between the peanut oil and the randomized peanut oil is probably caused by events subsequent to the release of cholesterol containing chylomicrons and very low density lipoproteins by the small intestinal epithelial cells.     

Oil-binding capacity of plastic fats: Effects of intermediate melting point TAG

The oil-binding capacity (OBC) of fat crystals was investigated as a function of intermediate melting point TAG (IMP-TAG) and stearin composition. Samples were prepared by melting 14% hard fraction (palm-canola stearin and IMP-TAG blends) in 86% liquid oil (olive, canola, safflower, and triolein) and crystallizing the mixture under fast and slow cooling conditions. Under fast cooling conditions, the OBC increased as the IMP-TAG/stearin ratio increased. The OBC is the grams of bound oil (determined by centrifugation) divided by the grams of solid fat (determined by pulse NMR). The maximum OBC was observed at 14% IMP-TAG and 0% stearin. In constrast, under slow cooling conditions, the 14% IMP-TAG and 0% stearin sample did not form crystals, and only free oil was present. The OBC for each liquid oil was lower under slow cooling conditions than under fast cooling conditions when compared at the same IMP-TAG/ stearin ratio. Solid fat content and RP-HPLC analyses indicated that IMP-TAG were retained in the crystal structure when processed under fast cooling conditions. RP-HPLC analyses also revealed that TAG with two saturated FA were retained in the crystal structure and that the monosaturated TAG were not. It was concluded that the TAG composition and cooling conditions played an important role in determining the OBC.