Fatty acid composition of rice lipids by gas-liquid chromatography

Gas-liquid Chromatographic analysis of the methyl ester of lipids of four rice varieties showed that bran lipids had significantly higher mean contents of linoleic and linolenic acids, but lower contents of myristic, palmitic, palmitoleic, and stearic acids than milled rice lipids. Nine fatty acids were detected. The principal components were oleic, linoleic, and palmitic, which also was confirmed by thin-layer chromatography of the esters. Issued as I.R.R.I. Journal Series No. 12     

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.     

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.     

Rice brain oil. II. Composition of oil obtained by solvent extraction

Summary The characteristics and composition of two crude and one refined rice bran oils have been determined. These oils were obtained by solvent extraction of commercial rice brans from Texas-grown Blue Bonnet and Arkansas-grown Zenith varieties of rice. The glyceride comosition of the two crude and one refined oils was found to be: 0.80, 1.06, and 0.84% linolenic acid; 33.2, 30.6, and 33.1% linoleic acid; 45.0, 46.0, and 46.3% oleic acid; 17.1, 17.3, and 17.1% saturated acids; and 3.9, 5.0, and 2.7% unsaponifiable matter, respectively. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

米糠油改性环氧酯铁红防锈底漆

米糠油主要由油酸、亚油酸和棕榈酸组成，属半干性油，具有了作为涂料基料的良好理化特性。研究表明，选用米糠油、桐油、环氧树脂和氧化铁红合成的铁红环氧酯防锈底漆，具有无毒、低温固化、防锈能力强等特点。本介绍了底漆的配方、生产工艺，并讨论了影响底漆性能的因素。     

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.     

Effects of drying methods and enzyme aided on the fatty acid profiles and lipid oxidation of rice by-products

We investigated the influence of hot air drying, far infrared radiation (FIR), and cellulase aided on the fatty acid composition and primary lipid oxidation of rice bran, rice husk, and ground rice husk. The lipid content was significantly reduced in the sample dried by hot air and FIR but remained unchanged in the cellulase-aided rice bran and husk. We found that oleic acid (18:1n ? 7) and linoleic acid (18:2n ? 6) increased in hot air- and FIR-dried rice bran. On the other hand, PUFA content was significantly reduced in the samples dried by hot air and FIR but remained unchanged in the cellulase-aided rice bran and husk. Cellulase aided gave significantly higher concentrations of SFA, MUFA, and PUFA in all samples than did hot air and FIR drying. However, the rice by-products dried with hot air and FIR had the lowest PV and TBA values during 30 days of storage. Our findings provide useful information for the pretreatment of rice by-products; consequently, more utilization of rice by-products will be extended for uses such as oil production.     

Chemistry of Color Fixation in Crude,Physically Refined and Chemically Refined Rice Bran Oils upon Heating

Compared to other vegetable oils, rice bran oil (RBO) has a characteristic dark color which further deepens upon heating or frying of foods in the oil. Darkening of the oil during heating has been studied. The dark color‐causing material in crude, chemically refined and physically refined rice bran oils was separated using a silica gel column for a hexane‐eluted oil fraction and a methanol eluted fraction. The methanol eluted fraction for all the above three types of RBO produced a dark color upon heating, hence the physically refined RBO methanol fraction was investigated further and contained monoglycerides (23.4 %) and diglycerides (67.4 %) of linoleic + linolenic acids in its methanol fraction as analyzed by column chromatography and HPLC which decreased in concentration after heating. The linoleic acid level of 37.7 % in the methanol fraction was reduced significantly to 18 % after heating (52.3 % reduction). The IR and NMR spectra were similar to those of a monoglyceride/diglyceride with NMR spectra indicating a lower amount of olefinic protons for the heated sample. These results showed that the darkening of RBO was due to the oxidation and polymerization of monoglycerides/diglycerides containing linoleic acid/linolenic acid.     

Studies on changes in fatty acid composition and content of endogenous antioxidants during γ irradiation of rice seeds

Accelerated aging effects, induced by y irradiation, were investigated on the fatty acid composition of lipids and on the content of endogenous antioxidants of four Indica and four Japonica rice seeds with and without intact hull. While the linoleic acid content of the phospholipids decreased gradually with the increase in irradiation doses, there was a corresponding increase in the linoleic acid content of the free fatty acids. Such changes were drastic, especially in the case of Japonica rice seeds irradiated without intact hull. However, the neutral lipids were found to be resistant to γ irradiation. The α-tocopherol content was found to decrease (markedly) in rice seeds irradiated with or without hull, especially in the Japonica rice seeds. At a dose of 15 kGy only traces of a-tocopherol could be detected in Japonica and Indica rice seeds irradiated with and without intact hull. Oryzanol, a relatively weaker anti-oxidant, was found to be more resistant to oxidative damage than a-tocopherol. At 15 kGy, the oryzanol content ranged from 59 μg to 170 μg/g lipid in rice seeds irradiated with intact hull, while the corresponding value for rice seeds irradiated without hull was 52 μg to 153 μg/g lipid. The overall susceptibility to oxidative damage was less in Indica rice seeds, indicating that the antioxidative defense system offered better protection in overcoming oxidative stress in Indica rice hull than in Japonica rice hull.     

Utilization of rice bran oil to produce an antifoamer

Crude rice bran oil was dewaxed by chilling to 17°C, followed by centrifuging. The wax sludge obtained was 68% free fatty acids and 32% waxes, whereas the oil phase was 65.65% fatty acids and 34.35% glycerides. The dewaxed oil was evaluated as an antifoaming agent for aqueous media and compared to commercial oleic acid. It was thought that dewaxed rice bran oil has an antifoaming power greater than oleic acid, especially when used in small proportions. Dewaxed rice bran oil was also applied to break and control the foam formation in a phosphoric acid production unit.     

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.     

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.     

An Update on the Use of Co-products from the Milling of Rice in Value-Added Food Products

Because of the large amount of rice produced annually, milled rice co-products, such as rice flour, rice bran, rice bran oil, wax, and rice hulls are plentiful and readily available. These co-products are valuable sources of food ingredients, but they are currently under-utilized. Rice bran and flour contain different levels of protein. When treated with carbohydrate-hydrolyzing enzymes, high-protein products can be produced, which are nutritious and used widely in health and baby food formulations. Recently, subcritical water processing has also been studied, in which water is put under high pressure to maintain its liquid state and used as an environmental-friendly media for the recovery of rice bran proteins. Rice flour contains more than 90% rice starch (RS), and functional properties of RS are normally modified to suit the needs for food applications. For example, the addition of small amounts of phosphorylated RS esters or pregelatinized rice flour to frying batters made of rice flour was found to impart superior sensory characteristics and lower the amount of oil-uptake. Reductions in oil uptake of up to 50% were observed with the rice based formulations compared with batters made from traditional wheat ingredients. Treatment of RS with octenylsuccinic anhydride produces modified starch products that are useful as an emulsifying agent for the encapsulation of lipophilic compounds. Similarly, other rice-based products, such as microcrystalline celluloses from rice hulls, edible films formed with rice wax, various components with antioxidant properties, and germinated brown rice flours have also been developed.     

Lipid synthesis and acyl-CoA synthetase in developing rice seeds

Developing rice seeds rapidly accumulated storage lipids between 5 and 12 d after flowering. The contents of palmitic, oleic, and linoleic acids increased throughout seed development, while the alpha-linolenic acid content remained low. The activity of acyl-CoA synthetase varied coincidentally during the period of lipid accumulation, and rice seeds had a sufficient capacity to supply acyl-CoA substrates for TAG synthesis. Acyl-CoA synthetase showed a broad specificity for native FA of rice seeds except for stearic acid, and pi electrons of a delta9-delta11 double bond in the C16-C18 acyl chains were required for its maximal activity.     

Composition of Rice Bran Stearin from Various Refineries Across China

In this study, we evaluated the composition of rice bran stearin (RBS) from various refineries across China. Here, we report the physicochemical parameters of RBS. The slip melting point ranged from 20.8 to 35.3 °C. The free fatty acid content (0.05–0.27 %) and peroxide value (0.34–3.70 mequiv oxygen/kg) was quite low, indicating that the RBS was of good quality. The iodine value ranged from 85.8–102.9 g/100 g, indicating a high unsaturated bond content. There was a significant difference in the unsaponifiable matter content (1.20–3.87 %) among RBS samples. The oxidative stability index (OSI) ranged from 0.56 to 5.85 h. The palmitic acid content in RBS refined by molecular distillation was significantly higher than the RBS that was refined physically and chemically. The major triacylglycerol was LLO/OLL, PLL/LPL, OLO, PLP, OOO and POO (L, linoleic acid; O, oleic acid; P, palmitic acid). RBS contained high levels of micronutrients, including total tocopherols (23.3–117.9 mg/100 g), oryzanol (0.1–2.1 %), and total sterols (682.9–1787.3 mg/100 g). Moreover, three different kinds of solid fat curves were distinguished. The results presented here are probably the first report regarding RBS on an industrial scale, meanwhile the potential utilization of RBS is discussed.     

Lipid hydrolysis and oxidation on the surface of milled rice

The changes in milled rice FFA content and composition and in conjugated diene (CD) content and bacterial, yeast, and mold counts were determined at 24, 37, and 50°C and 70% RH over 50 d. There was a rapid rate of FFA formation during the first few days of storage, which was optimal at 37°C, but that slowed after 2, 4, and 5 d at 37, 24, and 50°C, respectively. There was a second increase in FFA after about day 12 that increased with increasing temperature, indicating nonlipase hydrolysis. Linoleic and oleic acids were the main components of the total FFA produced on the surface of milled rice. The pattern of CD development followed that of FFA increase. Bacterial growth correlated with increased FFA levels after 12 d of storage, suggesting that bacterial lipase rather than bran lipase may be responsible for rice lipid hydrolysis     

Oil content and fatty acid composition of peanuts imported into japan

The oil content and fatty acid composition of Virginia, Runner, and Spanish market types of peanuts imported into Japan were determined. The significant differences among the countries of production were shown in stearic, eicosenoic and lignoceric acid contents of Virginia market type and oil content and palmitic, stearic, oleic, linoleic, eicosenoic, behenic and lignoceric acid contents of Spanish market type. The Spanish market type, as compared with the Virginia market type, was significantly higher in palmitic, stearic, linoleic, arachidic and behenic acid contents and lower in oleic, eicosenoic and lignoceric acid contents on the gross samples.     

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.

     

Veränderungen verschiedener Inhaltsstoffe in einzelnen Sonnenblumenfrüchten nach mutagener Behandlung in M2 und M3

Changes in Various Components in Single Sunflower Fruits after Mutagenous Treatment in M₂ and M₃ These investigations had the goal to find two different oil types with high linoleic acid content for dietfood at the one side and with high oleic acid content for special purposes for example as frying oils at the other side. By mutagenic treatment with Ethyl-methane-sulfonate and radiation the variability of fatty acid composition should be increased. After EMS-treatment a variation range from 36.6 to 83.4% linoleic acid and from 10.6 to 44.8% oleic acid was found by means of single seed investigations. After radiation with 10 KR x-rays linoleic acid content varied from 43.5 to 84.9% and oleic acid content varied from 9.2 to 42.4%. Oil and protein content as well as hull percentage of single seeds had wide variation, too. Correlation calculations showed highly negative correlations between contents of oleic and linoleic acid in all cases and partially relations between fruit size and oil and protein content.     

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.