Rice brain oil. I. Oil obtained by solvent extraction

1. Freshly milled rice bran has been extracted with commercial hexane and the recovered oil and extracted meal examined for their respective content of wax. The oils were refined and bleached by standards as well as several special methods. The crude, caustic soda refined, and several refined and bleached oils were examined spectrophotometrically.
2. When freshly milled rice bran of good quality is extracted with commercial hexane, an oil of relatively low free fatty acid content is obtained. This oil possesses good color and is as stable as other similar types of crude oils.
3. If the oils is extracted from the brain at a temperature below about 10°C. and the extraction is discontinued at the right time, the extracted oil represents 90–95% of the total lipids in the brain and contains very little wax. This wax, which is readily extracted with hot commercial hexane as well as other types of solvents, amounts to about 3–9% of the total extractable lipids.
4. When subjected to ordinary caustic soda refining methods, good rice brain oils behave much like cottonseed oils of comparable free fatty acid content. Both caustic soda refining in a hydrocarbon solvent and refining with sodium carbonate result in refining losses approximating the absolute or Wesson loss.
5. Some of the refined oils when bleached according to usual practice produce products acceptable for use in the edible trade. However, refined rice bran oil has a definitely greenish cast resulting from the presence of chlorophyll, but this color can be removed by bleaching with a small amount of activated acidic clay.

     

Rice bran oil. V. The stability and processing characteristics of some rice bran oils

1. The extraction, processing, characteristics, and stability properties of nine batches of hexane-extracted rice bran oil were investigated. The oils were refined, bleached, and deodorized and their color and stability determined. Samples of the bleached oils were hydrogenated to approximately shortening consistency, deodorized, and the stability of the hydrogenated products determined.
2. Pilot plant extractions of five batches of rice bran yielded crude oils equivalent to 91% of the hexane-soluble portions of the bran.
3. The nine crude oils whose content of free fatty acids ranged from 2.0 to 6.3% were refined by the cup method with losses ranging from 12.0 to 23.5% although the neutral oil content of six crude rice bran oils ranged from 89.9 to 92.6%.
4. The Lovibond color of the nine refined oils ranged from 35 yellow and 4.5 red to 70 yellow and 9.5 red, and the color of the bleached oils ranged from 15 yellow and 1.5 red to 35 yellow and 3.2 red.
5. Steam-refining, employed in conjunction with alkali-refining, proved effective as a means of reducing the losses in refining rice bran oil.
6. The nine batches of refined, bleached, and deodorized rice bran oils had iodine values ranging from 101.3 to 105.7 and stabilities averaging 24 hours.
7. Nine bleached oils hydrogenated to approximate shortening consistency had iodine values averaging approximately 66 and stabilities averaging 370 hours.
8. Refined, bleached, and deodorized rice bran oil is bland but has some tendency toward flavor reversion.
9. The most outstanding characteristics of rice bran oil is its exceptional stability after hydrogenation.

     

Sesame oil.I. Properties of a solvent-extracted sesame oil

Summary Data and information have been presented with respect to the extraction, processing characteristics, and the chemical and physical characteristics of oil obtained from white sesame seed. Extraction of sesame seed with hexane yielded a crude oil low in free fatty acids and in color. The oil was refined with caustic soda under a variety of conditions with low losses and bleached with comparatively small quantities of several bleaching earths each of which produced a light-colored oil. Data have been presented on progressive changes which occurred in the composition, stability, plasticity, and refractive index of the fat during selective hydrogenation of the refined and bleached oils. Sesame oil hydrogenated to shortening consistency exhibited extremely high stability when tested by the accelerated active oxygen method. This stability confirms previous suggestions that sesame oil contains one or more antioxidants of greater activity than those present in most of the other vegetable oils of commerce. Presented at the International Sesame Conference, Clemson Agricultural College, Clemson, South Carolina, August 15–16, 1949. Trainee at the Southern Regional Research Laboratory, August 26, 1947 to April 1, 1948. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Steam-Refined soybean oil: I. effect of refining and degumming methods on oil quality

A lot of commercially extracted crude soybean oil was water degummed with and without a phosphoric acid pretreatment. The degummed oils were bleached and then deacidified-deodorized in a single step to yield physically (steam) refined soybean salad oils. Their flavor and oxidative stability were compared to caustic-refined oils given otherwise identical processing treatments. Physically refined oils without a phosphoric acid pretreatment were of poor initial quality compared to those given the phosphoric acid pretreatment. However, caustic- and steam-refined oils processed with the phosphoric pretreatment were of comparable quality. Presented in part at the AOCS-AACC Symposium, Current Concepts of Food Ingredients, Chicago, March 1977.     

Processing of cottonseed

Summary Processing of cottonseed by the hydraulic press method has been carried out at two mills, one located about 100 miles farther south than the other. The varieties of seed processed and conditions during processing, which included cooking of moistened seed, were essentially the same at both mills. Seed was also processed at the more southerly mill by the screw press method for which seed was cooked without added moisture. The crude hydraulic- and screw-pressed oils produced at the two mills were stored at different temperatures for a total of ten months, and samples of the oils were periodically refined and bleached. Seed was also stored at the two mills, and was periodically processed for comparison of the oils produced from stored seed with the stored oils. The absorption spectra of the crude, refined, and bleached oils were determined. The rate of increase of bleach color in the oils during storage of the seed and crude oils has been correlated with temperature of storage and changes in the absorption spectra of the oils. Presented before the 38th Annual Meeting of the American Oil Chemists' Society, New Orleans, Louisiana, May 20–22, 1947. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Effect of refining of crude rice bran oil on the retention of oryzanol in the refined oil

The effect of different processing steps of refining on retention or the availability of oryzanol in refined oil and the oryzanol composition of Indian paddy cultivars and commercial products of the rice bran oil (RBO) industry were investigated. Degumming and dewaxing of crude RBO removed only 1.1 and 5.9% of oryzanol while the alkali treatment removed 93.0 to 94.6% of oryzanol from the original crude oil. Irrespective of the strength of alkali (12 to 20° Be studied), retention of oryzanol in the refined RBO was only 5.4–17.2% for crude oil, 5.9–15.0% for degummed oil, and 7.0 to 9.7% for degummed and dewaxed oil. The oryzanol content of oil extracted from the bran of 18 Indian paddy cultivars ranged from 1.63 to 2.72%, which is the first report of its kind in the literature on oryzanol content. The oryzanol content ranged from 1.1 to 1.74% for physically refined RBO while for alkali-refined oil it was 0.19–0.20%. The oil subjected to physical refining (commercial sample) retained the original amount of oryzanol after refining (1.60 and 1.74%), whereas the chemically refined oil showed a considerably lower amount (0.19%). Thus, the oryzanol, which is lost during the chemical refining process, has been carried into the soapstock. The content of oryzanol of the commercial RBO, soapstock, acid oil, and deodorizer distillate were in the range: 1.7–2.1, 6.3–6.9, 3.3–7.4, and 0.79%, respectively. These results showed that the processing steps—viz., degumming (1.1%), dewaxing (5.9%), physical refining (0%), bleaching and deodorization of the oil—did not affect the content of oryzanol appreciably, while 83–95% of it was lost during alkali refining. The oryzanol composition of crude oil and soapstock as determined by high-performance liquid chromatography indicated 24-methylene cycloartanyl ferulate (30–38%) and campesteryl ferulate (24.4–26.9%) as the major ferulates. The results presented here are probably the first systematic report on oryzanol availability in differently processed RBO, soapstocks, acid oils, and for oils of Indian paddy cultivars.     

Refining cottonseed oil at high rates of shear

Summary Ten crude cottonseed oils obtained from different areas in the South and Southwest were refined with and without the use of high-shear agitation in the step involving the initial mixing of the crude oil and caustic soda solution. In each instance the use of high shear produced a lower color in the refined oil. The improvement with some oils was not marked because they either refined very well by the ordinary method or failed for some unexplained reason to respond readily to high-shear mixing. However a good proportion of the oils which were quite dark after refining by the ordinary method refined to a much lighter oil when high shear was used. It was established that in high shear refining the color of the refined oil decreased as the temperature at which high shear was used decreased, the time at high shear increased, and the rate at which shear was applied increased. However an increase in the latter above a certain value had no effect. Also it was found that the color of the refined oil decreased as the amount and strength of the caustic soda solution increased. Absorption spectra of some of the processed oils indicated that high shear was more effective than ordinary mixing in removing from an oil the gossypol-like and carotenoid color bodies. Presented at the 28th fall meeting of The American Oil Chemists’ Society, Minneapolis, Minn., Oct. 11–13, 1954. One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Characteristics and composition of libyan olive oil

Chemical and physical characteristics of local olive oil (both virgin and refined) were determined. The moisture levels in olive fruit, cake and oils were 11.77, 12.7 and 0.16% respectively. The total crude fat on dry basis was: fruit, 39%; and cake, 7%. The free fatty acids (FFA) in both virgin and refined oils were high (4.4 and 4.3%). The samples of virgin as well as refined oil were found to have relatively low oleic acid contents (43.7 and 46.4%). However, linoleic acid was found to be higher than expected and the total of oleic and linoleic acids was more than 75% in the fraction of neutral lipids. The total saturated and unsaturated fatty acids in olive oil samples was ca. 20 and 80%, respectively.     

Effects of plant‐scale alkali refining and physical refining on the quality of rapeseed oil

The physical refining of soybean oil was introduced as an energy saving and environmentally friendly procedure alternative to the traditional alkali refining, and the process was successfully applied to other vegetable oils. We had compared the two procedures in industrial refining under conditions, which enable a clear comparison. In nine plant‐scale experiments, crude rapeseed oil, taken from the same tank of crude oil, was processed on the same day both by alkali refining and by physical refining. Quality changes (free fatty acids, peroxide value, conjugated fatty acids, polar lipids, minor constituents) were determined, and also their stability against oxidation (Rancimat and Schaal Oven Test), and the fatty acid composition. In refined oils, the sensory acceptabilities and the sensory profiles were assayed. Finally deodorized oils, produced by the two methods, did not appreciably differ in their sensory characteristics and chemical composition, excepting slightly higher concentration of isomeric polyunsaturated fatty acids in physically refined oils. During storage for one year in commercial packagings at 15 °C, oxidative and sensory changes were negligible.     

The properties ofCucurbita foetidissima seed oil

Oils from the seeds of 15 different selections of the buffalo gourd,Cucurbita foetidissima, were characterized in terms of their physical and chemical properties, which indicate that this oil is similar to other common edible oils. Xanthophylls were the predominant carotenoid pigments present in the crude oil, ranging from 51~232 mg/kg oil. Linoleic acid, the predominant fatty acid, ranged from 39~77% with an average level of 61%. Although conjugated unsaturated acids are a significant component in some other xerophytic cucurbit oils, the levels of conjugated dienoic and trienoic fatty acids in this species are only 2.3 and 0.03%, respectively. Arizona Agricultural Experiment Station No. 3081.     

Effect of the full refining process on rice bran oil composition and its heat stability

The effects of the chemical refining process on the minor compounds of rice bran oil and its heat stability were investigated. After 8 h of heating, about 50% and 30% of total tocopherols remained in crude and refined rice bran oil, respectively. The individual tocopherols were differently affected by the refining process. The order of heat stability of tocopherols and tocotrienols in crude oil was found to be different from that in fully refined oil. A similar tendency was observed for sterols. After 8 h of heating, 65% and 72% of total sterols, and 14% and 46% of sterol esters, of crude or fully refined rice bran oil, respectively, disappeared. The heating process led to a 4% and 10.3% increase in polymer contents in crude and refined rice bran oil, respectively. Although refined rice bran oil showed good heat stability, when compared to crude oil its heat stability was decreased to some extent.     

Study on the composition of rice bran oil and its higher free fatty acids value

The compositions of rice bran oils (RBO) and three commercial vegetable oils were investigated. For refined groundnut oil, refined sunflower oil, and refined safflower oil, color values were 1.5–2.0 Lovibond units, unsaponifiable matter contents were 0.15–1.40%, tocopherol contents were 30–60 mg%, and FFA levels were 0.05–0.10%, whereas refined RBO samples showed higher values of 7.6–15.5 Lovibond units for color, 2.5–3.2% for unsaponifiable matter, 48–70 mg% for tocopherols content, and 0.14–0.55% for FFA levels. Of the four oils, only RBO contained oryzanol, ranging from 0.14 to 1.39%. Highoryzanol RBO also showed higher FFA values compared with the other vegetable oils studied. The analyses of FA and glyceride compositions showed higher palmitic, oleic, and linoleic acid contents than reported values in some cases and higher partial glycerides content in RBO than the commonly used vegetable oils. Consequently, the TG level was 79.9–92% in RBO whereas it was >95% in the other oils studied. Thus, refined RBO showed higher FFA values, variable oryzanol contents, and higher partial acylglycerol contents than commercial vegetable oils having lower FFA values and higher TG levels. The higher oryzanol levels in RBO may contribute to the higher FFA values in this oil.     

Effect of processing on the oxidative stability of low erucic acid turnip rapeseed (Brassica rapa) oil

The effect of various processing conditions on the composition and the oxidative stability of mechanically pressed (90–95°C) rapeseed oil was investigated. The five different rapeseed oils included crude (nondegummed), superdegummed, steam stripped (at 140°C for 4h, nondegummed), physically refined (degummed, bleached and deodorized at 240°C), and cold pressed (40°C) oils. Oils were autoxidized in the dark at 60°C and under light at 25°C. Oxidation was followed by measuring changes in the peroxide values (PV) and the consumption of tocopherol and carotenoid was measured. In the dark the oils reached PVs of 10 meq/kg in the order: cold pressed > superdegummed > steam stripped ≅ crude > refined. However, under light conditions the order changed as follows: cold pressed > crude ≅ steam stripped > superdegummed > refined. Processing had no effect on fatty acid composition nor α-tocopherol content of the oils. Superdegumming and steam stripping decreased the carotenoid content of the oils while cold pressing and refining reduced also chlorophyll, γ-tocopherol and phosphorus content of the oils.     

Iodine values of acidulated coconut oil soapstock

Summary Analyses and comparisons of a number of representative samples have shown that acidulated coconut oil soapstock may have an iodine value as much as 100% greater than that of the corresponding refined oil without any contamination being involved. Exactly what the spread between any given soapstock and oil will be apparently depends on the free fatty acid content of the original crude oil and the relative efficiency of the refining process. It was found that, for coconut soapstocks produced by standard laboratory refining tests, the relation between free fatty acid content and iodine value spread can be represented by the formula I.V. Spread=9.5–759 FFA. The efficiency of the refining process affects results insofar as it reduces the entrainment of neutral oil. Removing all of the neutral oil from four laboratory-produced soapstocks prior to acidulation raised the iodine value approximately two units in all cases. The practical significance of these results is obvious. A refiner processing high grade crude coconut oil of 9.5, iodine value by a highly efficient refining procedure cannot be expected to produce an acidulated soapstock of less than about 18.0 in iodine value. With higher free fatty acid crude oil and less efficient refining procedures lower iodine values are possible, but since soapstock is of minor economic value compared to refined oil, the trend will always be toward better grade crude oils and more efficient refining processes.     

Lipase‐catalyzed production of biodiesel from rice bran oil

Biodiesel has attracted considerable attention as an alternative fuel during the past decades. The main hurdle to the commercialization of biodiesel is the cost of the raw material. Use of an inexpensive raw material such as rice bran oil is an attractive option to lower the cost of biodiesel. Two commercially available immobilized lipases, Novozym 435 and IM 60, were employed as catalyst for the reaction of rice bran oil and methanol. Novozym 435 was found to be more effective in catalyzing the methanolysis of rice bran oil. Methanolysis of refined rice bran oil and fatty acids (derived from rice bran oil) catalyzed by Novozym 435 (5% based on oil weight) can reach a conversion of over 98% in 6 h and 1 h, respectively. Methanolysis of rice bran oil with a free fatty acid content higher than 18% resulted in lower conversions (<68%). A two‐step lipase‐catalyzed methanolysis of rice bran oil was developed for the efficient conversion of both free fatty acid and acylglycerides into fatty acid methyl ester. More than 98% conversion can be obtained in 4–6 h depending on the relative proportion of free fatty acid and acylglycerides in the rice bran oil. Inactivation of lipase by phospholipids and other minor components was observed during the methanolysis of crude rice bran oil. Simultaneous dewaxing/degumming proved to be efficient in removing phospholipids and other minor components that inhibit lipase activity from crude rice bran oil. Copyright © 2005 Society of Chemical Industry     

Crude oil analysis

Summary It has been shown that it is easily possible to obtain the exact amount of refined oil in a given sample of crude by an accurate analytical method. The refining efficiency in a well operated refinery is 96.5 per cent on prime crude oils. That proper settling of crude oil results in an increase of the absolute oil of 1.5 per cent and upwards. That the free fatty acid test may show acidity due to other causes than free fatty acids.     

Sesame oil. VI. Determination of sesamin

Summary A new method for the determination of sesamin in sesame oils is described. It is based on the measurement of the ultraviolet absorption of sesame oil following the removal of sesamol by treatment with alkali and correction for the absorption resulting from the presence of sesamolin. The advantages of the new method over the previously described colorimetric method are discussed. The accuracy of the method is attested by a comparison of the determined values with those for known added amounts of sesamin in cottonseed and sesame oils. When applied to four crude oils, the content of sesamin was found to range from 0.50 to 0.96%. Ultraviolet absorption spectra curves are reported for sesamin, sesamolin, sesamol, and sesame oil. Rockefeller Foundation Fellow from the Ministerio de Agricultura y Crfa, Division de Quimica, El Valle, D. F. Venezuela. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Membrane degumming and dewaxing of rice bran oil and its refining

A combined degumming-dewaxing batch by filtration through a ceramic membrane followed by earth bleaching and physical or alkali refining was studied for crude rice bran oil. The results were compared with the conventional centrifugal process for gum and wax removal. The characteristics of the refined oils obtained by the two processes were comparable. However, the former process was promising with respect to higher recovery of oil and better recovery of the byproducts gum and wax. Oil content of the mixed gum-wax phase was 7.6–8.1%. The recovery of oil using the membrane technique was always 2–3% higher than the centrifugal process. The membrane process was also found to be more effective and the quality of the final product was acceptable.     

Note on gossypol and its relation to color fixation in cottonseed oil

1. The crude oils studied contained from 0.00 to 0.04% gossypol.
2. Much of the gossypol added to crude cottonseed oils disappeared in one hour.
3. The disappearance of gossypol from refined, bleached, and deodorized cottonseed oil, from highly purified tripelargonin, and from ethyl acetate is demonstrable after the lapse of one hour.
4. It is suggested that the initial reaction of gossypol in the oils is an ester exchange reaction.
5. It is further suggested that secondary reactions result in the production of a red coloration product that is not removable from the oil by the standard refining and bleaching methods.

     

A modified method for determining free fatty acids from small soybean oil sample sizes

A modification of the AOCS Official Method Ca 5a-40 for determination of free fatty acids (FFA) in 0.3 to 6.0-g samples of refined and crude soybean oil is described. The modified method uses only about 10% of the weight of oil sample, alcohol volume, and alkali strength recommended in the Official Method. Standard solutions of refined and crude soybean oil with FFA concentrations between 0.01 and 75% were prepared by adding known weights of oleic acid. The FFA concentrations, determined from small sample sizes with the modified method, were compared with FFA percentages determined from larger sample sizes with the Official Method. Relationships among determinations obtained by the modified and official methods, for both refined and crude oils, were described by linear functions. The relationship for refined soybean oil had an R ² value of 0.997 and a slope of 0.99±0.031. The values for crude soybean oil are defined by a line with R ²=0.9996 and a slope of 1.01±0.013.