Isolation and identification of the causative factors responsible for color fixation in rice bran oil

To understand the chemical nature of the dark coloring constituents responsible for color fixation in rice bran oil, crude and dewaxed rice bran oils of 6.8% free fatty acids were fractionated on a silica gel column to get a dark-colored material (0.57% of the oil). Thin-layer chromatographic analysis of the material showed a spot corresponding to monoglycerides, but there were no spots corresponding to other glycerides. It contained traces of phosphorus (<0.1 ppm, which is equivalent to 2.5 ppm phospholipids) and iron (1.3 ppm) that could not be attributed to phospholipids or to any iron-complex. Upon saponification it yielded 12% nonsaponifiable matter. Gas-liquid chromatographic analysis of the saponifiable matter (after acidification and methylation of fatty acids) showed the presence of palamitic, oleic and linoleic acids. Further, on the basis of comparison with spectroscopic data of synthetic monoglyceride, the constituent was characterized to be a mixture of monoglycerides with side chains of oxidized unsaturated fatty acids.     

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     

Fatty Acid Composition of Indica-and Japonica-Types of Rice Bran and Milled Rice

Fatty acid compositions of 10 cultivars each of Indicaand Japonica types of rice bran and milled rice were investigated. The Indica-type, as compared with the Japonica-type, had significantly higher palmitic, stearic, linolenic, and arachidic acid contents and lower linoleic and eicosenoic acid contents in the bran and milled rice, and lower oleic acid content in the bran. The correlation coefficient between oleic and linoleic acid contents of bran and milled rice was negative in the Indica-and Japonica-types and was the highest between all fatty acids. The regression line in the scatter diagrams between oleic and linoleic acid contents of bran and milled rice divided the Indica and Japonica lines.     

Genetic diversity for lipid content and fatty acid profile in rice bran

Rice (Oryza sativa L.) bran contains valuable nutritional constituents, which include lipids with health benefits. A germplasm collection consisting of 204 genetically diverse rice accessions was grown under field conditions and evaluated for total oil content and fatty acid (FA) composition. Genotype effects were highly statistically significant for lipid content and FA profile (P<0.001). Environment (year) significantly affected oil content (P<0.05), as well as stearic, oleic, linoleic, and linolenic acids (all with P<0.01 or lower), but not palmitic acid. The oil content in rice bran varied relatively strongly, ranging from 17.3 to 27.4% (w/w). The major FA in bran oil were palmitic, oleic, and linoleic acids, which were in the ranges of 13.9–22.1, 35.9–49.2, and 27.3–41.0%, respectively. The ratio of saturated to unsaturated FA (S/U ratio) was highly related to the palmitic acid content (r ²=0.97). Japonica lines were characterized by a low palmitic acid content and S/U ratio, whereas Indica lines showed a high palmitic acid content and a high S/U ratio. The variation found suggests it is possible to select for both oil content and FA profile in rice bran.     

Isolation and Evaluation of Stearin and Olein Fractions from Rice Bran Oil Fatty Acid Distillate by Detergent Fractionation and Conversion into Neutral Glycerides by Autocatalytic Esterification Reaction

Detergent fractionation (Lanza process) offers a valuable separation process for edible oils that contain varying amounts of saturated and unsaturated fatty acids. The rice bran oil fatty acid distillate (RBOFAD), obtained as a major byproduct of rice bran oil deacidification refining process, was fractionated by detergent solution into a fatty acid mixture as follows: low-melting (19.00 °C) fraction of fatty acids as olein fraction (44.50 g/100 g) and high-melting (49.00 °C) fatty acids as stearin fraction (37.15 g/100 g). A high amount of palmitic acid (42.75 wt%) is present in stearin fraction, while oleic acid is higher (48.21 wt%) in the olein fraction. The stearin and olein fractions of RBOFAD with very high content of free fatty acids are converted into neutral glycerides by autocatalytic esterification reaction with a theoretical amount of glycerol at high temperatures (130–230 °C) and at a reduced pressure (30 mmHg). Acid value, peroxide value, saponification value, and unsaponifiable matters are important analytical parameters to identity for quality assurance. These neutral glyceride-rich stearin and olein fractions, along with unsaponifiable matters, can be used as nutritionally and functionally superior quality food ingredients in margarine and in baked goods as shortenings.     

<Emphasis Type="Italic">cis</Emphasis>-, <Emphasis Type="Italic">trans</Emphasis>- and Saturated Fatty Acids in Selected Hydrogenated and Refined Vegetable Oils in the Indian Market

The fatty acid composition of 27 samples of commercial hydrogenated vegetable oils and 23 samples of refined oils such as sunflower oil, rice bran oil, soybean oil and RBD palmolein marketed in India were analyzed. Total cis, trans unsaturated fatty acids (TFA) and saturated fatty acids (SFA) were determined. Out of the 27 hydrogenated fats, 11 % had TFA about 1 % where as 11 % had more than 5 % TFA with an average value of about 13.1 %. The 18:1 trans isomers, elaidic acid was the major trans contributor found to have an average value of about 10.8 % among the fats. The unsaturated fatty acids like cis-oleic acid, linoleic acid and α-linolenic acid were in the range of 21.8–40.2, 1.9–12.2, 0.0–0.7 % respectively. Out of the samples, eight fats had fatty acid profiles of low TFA (less than 10 %) and high polyunsaturated fatty acids (PUFA) such as linoleic and α-linolenic acid. They had a maximum TFA content of 7.3 % and PUFA of 11.7 %. Among the samples of refined oils, rice bran oil (5.8 %) and sunflower oil (4.4 %) had the maximum TFA content. RBD palmolein and rice bran oils had maximum saturated fatty acids content of 45.1 and 24.4 % respectively. RBD palmolein had a high monounsaturated fatty acids (MUFA) content of about 43.4 %, sunflower oil had a high linoleic acid content of about 56.1 % and soybean oil had a high α-linolenic acid content of about 5.3 %.     

Industrial hydrogenation of rice bran oil,a substitute for tallow

The Indian soap industry’s hard fat requirement was met until recent years by imported animal tallows. The search for alternate hard fats, consequent to the ban on the import of animal tallows in 1983, led to realization of the striking similarity in the fatty acid composition of mutton tallow and hydrogenated rice bran oil, except for thetrans oleic acid content. This paper traces the course of compositional changes undergone by rice bran oil during industrial hydrogenation, employing gas liquid chromatography and infra red spectroscopy.     

Enzymatic synthesis of capric acid-rich structured lipids (MUM type) using Candida antarctica lipase

The objective of the work was to produce capric acid rich structured lipids starting from various Indian indigenous vegetable oils, such as rice bran, ground nut and mustard oils. Acidolysis reaction between individual vegetable oils and capric acid in one is to three molar ratios at 45 degree centigrade temperature was carried out using position specific Candida antarctica lipase so as to protect the Sn-2 position of the oils which are rich in unsaturated fatty acids. The incorporation of capric acid depended on the reaction time showing 6 % within 6 h and 30.8 % in 72 h with rice bran oil. Similarly, in ground nut oil incorporation of capric acid was 34.2 % in 72 h compared to 5.3 % in 6 h. Thus mustard oil showed much lower incorporation than the other two oils, with 3.3 % and 19.5 % in 6 and 72 h respectively. The incorporation of capric acid was influenced by the nature of the fatty acids present in the original oil. The fatty acid composition of Sn-2 position of the structured triacylglycerols of the three oils revealed that capric acid was mainly replacing the fatty acids occupying the Sn-1 and 3 positions of the triglyceride molecule.     

Deacidification of high-acid rice bran oil by reesterification with monoglyceride

Autocatalytic esterification of free fatty acids (FFA) in rice bran oil (RBO) containing high FFA (9.5 to 35.0% w/w) was examined at a high temperature (210°C) and under low pressure (10 mm Hg). The study was conducted to determine the effectiveness of monoglyceride in esterifying the FFA of RBO. The study showed that monoglycerides can reduce the FFA level of degummed, dewaxed, and bleached RBO to an acceptable level (0.5±0.10 to 3.5±0.19% w/w) depending on the FFA content of the crude oil. This allows RBO to be alkali refined, bleached, and deodorized or simply deodorized after monoglyceride treatment to obtain a good quality oil. The color of the refined oil is dependent upon the color of the crude oil used.     

Biooxidation of fatty acid distillates to dibasic acids by a mutant of Candida tropicalis

Fatty acid distillates (FADs) produced during physical refining of vegetable oil contains large amount of free fatty acid. A mutant of Candida tropicalis (M20) obtained after several stages of UV mutation are utilized to produce dicarboxylic acids (DCAs) from the fatty acid distillates of rice bran, soybean, coconut, palm kernel and palm oil. Initially, fermentation study was carried out in shake flasks for 144 h. Products were isolated and identified by GLC analysis. Finally, fermentation was carried out in a 2 L jar fermenter, which yielded 62 g/L and 48 g/L of total dibasic acids from rice bran oil fatty acid distillate and coconut oil fatty acid distillate respectively. FADs can be effectively utilized to produce DCAs of various chain lengths by biooxidation process.     

Quantitative analysis of fatty acids and sterols in Malagasy rice bran oils

The fatty acid and sterol compositions of six Malagasy rice bran oils were evaluated. Investigation by gas liquid chromatography (GLC) using Carbowax 20 M revealed 10 fatty acids, mainly palmitic (16–20%) oleic (41–44%) and linolenic (31–37%) acids. An OV 17 column was used to separate eight sterols, mainly Β-sitosterol (53–59%), campesterol (16–26%) and stigmasterol (10–13%). No significant variation for the fatty acid and sterol contents was observed among the rice varieties studied.     

Effect of dewaxing pretreatment on composition and stability of rice bran oil: Potential antioxidant activity of wax fraction

The effect of dewaxing pretreatment on rice bran oil composition and stability was investigated, as well as the possibility to use rice bran oil waxes as natural antioxidants at high temperatures. A correlation between wax content and dewaxing time was noticed. The pre‐dewaxing process led to a loss of minor compounds, which negatively affected the oxidative stability index (OSI) of the dewaxed oil. The addition of rice bran oil waxes improved the oil stability index and heat stability of sunflower oil. An increase of 60% of the OSI and a significant decrease in polymer formation (59.2%) were observed.     

Indian ricebran lecithin

In view of the high potential of ricebran oil in India, lecithins recovered from crude and dewaxed Indian ricebran oil were analyzed and different classes characterized with the objective of effectively utilizing this valuable by- product. Lipid classes and individual phospholipid components were identified and estimated. Dewaxing was found to have a considerable effect on composition of the derived lecithin. The lecithin obtained from crude or dewaxed Indian ricebran oil consisted mainly of phosphatidylcholine, phosphatidylethanolamine, phosphatidylnositol and triglycerides, along with carbohydrates, free fatty acid, sterols and waxes (in case of crude oil). The major fatty acids of individual phospholipids were found to be palmitic, oleic and linoleic. Analytical characteristics of ricebran lecithin were shown to be comparable to local soybean lecithin. It can be expected that the gummy materials in the oil, presently lost with the soapstock during refining, could find important applications.     

米糠精制产品的应用

对米糠综合利用的途径进行了详细论述；并总结厂各种米糠精制产品在日用化工、医药工业、食品工业、精细化工领域的具体用途，包括米糠油的浸提技术，米糠油作为营养保健食品的开发利用，米糠油作为油脂化工原材料的深加工；米糠油精炼皂脚中提取游离脂肪酸及脂肪酸衍生物的制备；米糠脱水、脱臭、脱色的小皂化物提取谷甾醇、生育酚、谷维素的方法；米糠脱蜡副产物制备糠蜡和二十烷醇的利用及米糠饼(粕)提取植酸钙、植酸和肌醇的利用途径，最后提出了大力发展我国米糠产业的市场前景。     

Some chemical processes utilizing oleic safflower oil

Oleic safflower seed (UC-1) produces an oil containing approximately 80% oleic acid and 12% linoleic acid. The oil is a source of high quality oleic acid, and fatty acids from the oil may be used without further separation in some applications where technical oleic acid is now used, since oleic safflower free fatty acids have a a higher oleic acid content than good commercial grades of oleic acid. A high purity oleic acid can be produced by urea fractionation. Ozonization of the oil followed by reductive cleavage yields pelargonaldehyde and nearly colorless aldehyde oils. Ozonization of a crude mixture of oleic safflower acids followed by oxidative cleavage provides high yields of azelaic acid and pelargonic acid. In contrast, ozonization of free fatty acids from polyunsaturated vegetable oils produces azelaic acid and mixtures of lower molecular weight carboxylic acids with smaller amounts of pelargonic acid. Furtherore, ozone consumption is lower and reaction time is shorter when oleic safflower acids are used in place of more highly unsaturated fatty acids.     

Evaluation of physicochemical changes in cooking oil during heating

Rice bran oil and double fractionated palm olein (DF palm olein) were heated at 180 C for 50 hr to measure lipid deterioration in the oils. Free fatty acid content of both oils increased during heating; however, iodine value and smoke point decreased. Solid fat contents of both oils were unaffected by heating time. Cloud point of rice bran oil was much lower than that of palm olein. Color of oils changed gradually to dark brown from light yellow with increased heating time. Absolute content of polyunsaturated fatty acid, such as linoleic acid, reduced more than that of monounsaturated fatty acid, such as oleic acid, in both oils. In both oils, iodine value correlated very well with linoleic acid content, with correlation coefficient higher than 0.96.     

Effect of method of stabilization on aqueous extraction of rice bran oil

Rice bran oil is widely used in pharmaceutical, food and chemical industries due to its unique properties and high medicinal value. In this study aqueous extraction of rice bran oil from rice bran available in Sri Lanka, was studied. Key factors controlling the extraction and optimal operating conditions were identified. Several methods of bran stabilization were tested and the results were analyzed. The yield and quality of aqueous extracted oil was compared with hexane extracted oil.Aqueous extraction experiments were conducted in laboratory scale mixer–settler unit. Steaming, hot air drying, chemical stabilization and refrigeration better controls the lipase activity compared to solar drying. Steaming is the most effective stabilization technique. The extraction capacity was highest at solution pH range 10–12. Higher oil yield was observed at higher operating temperatures (60–80 °C). Kinetic studies revealed that extraction was fast with 95% or more of the extraction occurring within first 10–15 min of contact time. Parboiling of paddy increases the oil yield. Highest oil yield of 161 and 131 mg/g were observed for aqueous extraction of parboiled bran and raw rice bran respectively. The aqueous extracted oil was low in free fatty acid content and color compared to hexane extracted rice bran oil and other commonly used oils. Major lipid species in rice bran oil were oleic, linoleic and palmitic.     

In situ esterification of rice bran oil with methanol and ethanol

In situ esterifications of high-acidity rice bran oil with methanol and ethanol and with sulfuric acid as catalyst were investigated. In the esterification with methanol, all free fatty acids (FFA) dissolved in methanol were interesterified within 15 min, and it was possible to obtain nearly pure methyl esters. The amount of methyl esters obtained from a given rice bran was dependent on the FFA content of the rice bran oil. In the esterification with ethanol, it was not possible to obtain pure esters as in methanol esterification, because the solubilities of oil components in ethanol were much higher than those in methanol.     

Rice bran oil. IV. Storage of the bran as it affects hydrolysis of the oil

Summary and Conclusions The oil, contained in bran from regularly milled rice, when stored at prevailing atmospheric temperature, humidity, and natural moisture content is subject to rapid hydrolysis which increases the free fatty acid content of the oil to a point where it cannot be economically refined. Data have been presented showing the effects of a) temperature, b) drying at temperatures of 70°, 85°, 100°, and 110°C. for various periods of time up to 5 hours, c) different relative humidities before and after drying, and d) added moisture on the rate of formation of free fatty acids during storage in bran from both regular and “Converted” rice. Decreasing the storage temperature tends to retard the formation of free fatty acids. In the case of regular rice bran deterioration during storage occurred at a fairly rapid rate even at 3°C. whereas bran from “Converted” rice was fairly stable when stored at this temperature. The investigation of the effect of heating or drying and the effect of different relative humidities on the storage of rice bran have shown that bran from both regular and “Converted” rice can be stored for periods of at least four months without excessive increase in the content of free fatty acids, provided the bran is dried sufficiently and is maintained at a low moisture content. An increase in the moisture content of predried bran causes a rapid increase in the free fatty acid content of the oil in the bran. Investigations of the effect of chemical inhibitors and of inert atmosphere on the rate of free fatty acid formation of regular rice bran indicated that these were ineffective in preventing deterioration. Presented at the 40th Annual Meeting of the American Oil Chemists’ Society, New Orleans, La., May 10–12, 1949; Report of a Study Made Under the Research and Marketing Act of 1946. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Effect of Subcritical Carbon Dioxide Extraction and Bran Stabilization Methods on Rice Bran Oil

The extraction of rice bran oil using the conventional organic solvent‐based Soxhlet method involves hazardous chemicals, whereas supercritical fluid extraction is a costly high‐temperature operating system. The subcritical carbon dioxide Soxhlet (SCDS) system, which operates at a low temperature, was evaluated for the extraction of rice bran oil in this study. In addition, rice bran that had been subjected to steam or hot‐air stabilization were compared with unstabilized rice bran (control). The yields; contents of tocopherols, tocotrienols and oryzanol; fatty acid profiles; and the oxidative stabilities of the extracted rice bran oils were analyzed. The yields using hexane and SCDS extraction were approximately 22 and 13–14.5 %, respectively. However, oil extracted using the SCDS system contained approximately 10 times more oryzanol and tocol compounds and had lower free fatty acid levels and peroxide values compared with hexane‐extracted oil. Overall, SCDS extraction of steamed rice bran represents a promising method to produce premium‐quality rice bran oil.