Constituents of crude cottonseed oil

Summary Crude cottonseed oil contains in addition to the constituents previously reported a lecithin type of phosphatide which gives an ether-soluble compound with cadmium chloride. This phosphatide can only be partially removed from the oil by extraction with alcohol. It has been found in the “settlings” from this oil. The treatment of the oil with water causes only a partial separation of this phosphatide. The phosphatides, resins, and presumably other substances present in small quantities in the crude oil have emulsifying properties and are undoubtedly the cause in part for the retention of oil in the soap stock when the oil is refined by caustic soda.     

Characterizing Lecithin Interactions in Chocolate Using Interfacial Properties and Rheology

The functionality of chocolate is based on specific properties including how it flows. Cocoa butter and lecithin are two ingredients that help to control the flow properties of melted chocolate. Lecithin is an emulsifier that has been the preferred method of providing yield stress and viscosity control while reducing production costs by decreasing the amount of cocoa butter needed to achieve similar flow results. In this industrially oriented study, soy, sunflower, and dairy lecithin were compared by quantifying interfacial and rheological properties of lecithin in dark chocolate. Each lecithin source was added up to the 1.0% limit, which is the emulsifier maximum set forth by the Code of Federal Regulations. The compositions of each lecithin source were analyzed for total phospholipid composition, which were used to normalize data based on the total added phosphatides added for all samples. Differences in both phosphatide composition and fatty acid composition were found. Both interfacial tension between oil and water phases and contact angle between a cocoa butter drop and flat sucrose crystal surface decreased as the phosphatide concentration increased for each lecithin source. In terms of rheology, the yield stress first decreased with increasing lecithin content and then began to increase, whereas plastic viscosity continually decreased with addition of lecithin. Significant differences were seen for the different lecithin sources, even when compared on an equivalent phosphatide content. No correlations were found between interfacial properties and yield stress; however, direct correlations were found between both interfacial measures and plastic viscosity.     

Improvement of lecithin as an emulsifier for water-in-oil emulsions by thermalization

The various forms (granular, liquid, gum) of lecithin can be heated under certain conditions of time and temperature to greatly improve their properties as emulsifiers for water-in-oil emulsions. Viscosity, discontinuous phase-holding capacity, stability and water retention were greatly enhanced in emulsions containing thermalized lecithins as the emulsifier compared to those prepared with corresponding amounts of nonthermalized lecithins. The improved emulsification properties of the thermalized lecithins appeared to be due, at least in part, to an increase in diglycerides and free fatty acids resulting from the thermal degradation of phosphatides.     

Chromatographically homogeneous lecithin from egg phospholipids

Chromatographically homogeneous egg lecithin, as determined by TLC on Silica Gel G, has been isolated from crude egg phosphatides by column chromatography on alumina through modification of existing, lengthy methods. The modified method involved application of crude egg phosphatides to a column of alumina in the proportion of 1 g phosphatide/25 g alumina, and elution of the lecithin fraction with the 2-component solvent system chloroform:methanol, 9:1 by vol. This method of purification separated lecithin from other choline and non-choline components of crude phosphatides, avoided overloading of the alumina column, and made unnecessary the need for a second chromatographic fractionation of partially purified lecithin on silicic acid, which is needed in existing methods of purification of lecithin. The use of fresh yolks permitted easier removal of pigment from the final product than was possible with commercially dried yolks. Phosphatides extracted from dried yolks were much more highly colored than were the phosphatides extracted from fresh yolks and the color presisted through chromatography on alumina. The fatty acid/phosphorus molar ratio of the purified lecithin was 2.00, which is the theoretical FA/P molar ratio of phosphatidylcholine; other materials with this ratio were not present. Presented at the AOCS Meeting, New Orleans, 1964. A laboratory of the So. Utiliz. Res. & Dev. Div., ARS, USDA.     

Preferential degradation of noncholine phosphatides in soybean lecithin by thermalization

Purified soybean lecithin and the gum derived from soybean oil processing were heated separately in bulk at 125 to 200°C for 60 min, or at 175°C for 30, 60, 90 and 120 min, and the products were analyzed by thin-layer chromatography and high-performance liquid chromatography. It was found that the noncholine phosphatides are preferentially degraded relative to phosphatidylcholine, and that these phosphatides are broken down in the order phosphatidyl-ethanolamine (PE)>phosphatidylinositol (PI)>phosphatidic acid (PA) with increasing temperature. At 175°C, the heating time required to degrade the noncholine phosphatides was between 30 and 60 min. Diglycerides were the principal products of thermalization at 77% of the total material, indicating that the 3-phosphoester linkage is the most heat-labile portion of the noncholine phosphatide molecules. Cleavage of the fatty acids from positions 1 and 2 of the phosphatides was minimal, as indicated by the relatively low amount of free fatty acids (8% of the total) when the lecithin was heated at 180°C for 90 min. The appearance of brown discoloration, characteristic of heated lecithin, coincided mainly with the decomposition of PE.     

A Process for the Separation of Phosphatide Mixtures: The Preparation of Phosphatidylethanolamine-free Phosphatides from Soya Lecithin

It is commonly accepted that phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol, the three major phosphatide constituents of soya lecithin are insoluble in acetone, and that extraction of the soya lecithin with acetone dissolves out the triglyceride oil and leaves a precipitate of a mixture of these three phosphatides. Intimate molecular association between phosphatides and acetone appears to be responsible for this. This paper presents a mechanistic picture for this association, discusses the means for preventing this association, and thereby dissolving phosphatides into acetone. A prospect for dissolving phosphatidylethanolamine into acetone, preferentially over others from a mixture, is thus opened up. This is important since it has practical applications in industry. It has been exploited by the development of a process for the separation of phosphatidylcholine and phosphatidylinositol (mixture) from commercial soya lecithin. The process solves a long standing industrial problem for the preparation of phosphatidylethanolamine-free phosphatides.     

Effect of sunflower lecithins on the stability of water-in-oil and oil-in-water emulsions

Lecithins are frequently applied in the food industry as emulsifiers, viscosity regulators, and dispersing agents. The main aim of the present work was to study the emulsifying capability of diverse sunflower lecithins so as to evaluate the functionality of these by-products, which are not extensively used at present. The experimental results obtained for water-in-oil (W/O) emulsions showe that dispersions containing levels of 0.1% lecithins were more stable against coalescence than a control system, whereas those with 1% emulsifying agent exhibited the opposite behavior. On the other hand, faster sedimentation kinetics were observed at a concentration of 0.1% than at 1%. Lecithins with high phospholipid content, especially phosphatidylethanolamine and phosphatidylinositol, were found to be the best emulsifying agents for W/O dispersions. In the case of oil-in-water emulsions, it was possible to observe two processes: creaming of emulsions with the addition of 1% of lecithins, and instant creaming followed by coalescence of the cream phase in those cases corresponding to 0.1% added lecithin.     

硅油乳状液制备新工艺研究

以二甲基硅油(500 000 mm2/s)为原料,AEO3、AEO7、OP乳化剂组成复配乳化剂,用自主研发的搅拌器,成功在常温下制备出固含量约为56%的硅油乳液。考察了乳化剂选择、乳化方法、乳化剂用量、乳化时间等因素对硅油乳液性能的影响。结果表明,硅油乳化的最佳工艺条件是:采用剂在油中法,乳化剂用量为5%(相对于乳液总质量),乳化时间为80 m in。在此条件下,得到的硅油乳液外观均匀、细腻,具有良好的稳定性和分散性。所得乳液不必调节pH值,工艺实现简化。     

Degumming soybean oil from fresh and damaged beans with surface-active compounds

Oils from both properly stored and damaged soybeans were degummed with a series of 4 nonionic, 2 cationic and 5 anionic surfactants and with lecithins as amphoteric emulsifiers. Efficiency of phosphatide removal in the presence or absence of citric acid was determined by colorimetric analysis of phosphorus in the degummed oils. For normal oils, efficiency of citric acid degumming was improved by the addition of fatty alkyl oxazoline, polymeric sulfonate, alkyl sulfate and crude or purified lecithin. Success in degumming of oils from partially damaged soybeans was limited; however, the average phosphorus content was lowest for those solutions degummed with alkyl sulfate. Aqueous citric acid degumming of oils from severely damaged soybeans indicated high levels of nonhydratable phosphatides (NHP). When added to the oil from severely damaged beans, several nonionic and anionic surfactants showed statistically significant improvements in degumming efficiency. However, the nonhydratable phosphorus contents of the degummed oils were still too high, indicating the need for special processing of damaged oils. Crude lecithin was effective in removing NHP from oil of fresh soybeans, but was ineffective on oils of stored and severely damaged beans. Biometrician, North Central Region, ARS, USDA, stationed at the Northern Regional Research Center, Peoria, Illinois 61604.     

Composition of soybean lecithin

Commercial soybean lecithin is a complex mixture containing ca. 65–75% phospholipids together with triglycerides and smaller amounts of other substances. The major phospholipids include phosphatidylcholine, phosphatidylethanolamine and inositol-containing phosphatides. Other substances reported include carbohydrates, pigments, sterols and sterol glycosides. This paper reviews the nature of the compounds found in soybean lecithin and our present knowledge of its composition.     

Phosphatides in American soy beans and oil

Summary It has been found that the precipitate separating from clarified expressed crude oil from soy beans grown in North Carolina and Virginia is composed chiefly of phosphatides. Methods have been described for the determination of phosphatide phosphorus in soy beans which is applicable to seeds in general and in the oil. Soy beans of the more important varieties used by the oil mills both in the Eastern and Middle West States have been examined for their respective phosphatide content. With but few exceptions it was found that the beans grown in the East contained less phosphatides than those from the West, which indicated that the quantity of these substances present is not a factor in causing a partial separation of them in some oils but not in others. Regardless of whether or not a separation of phosphatides takes place, all the crude soy bean oils which have been examined so far have contained notable quantities of them.     

Emulsifying Properties of Different Modified Sunflower Lecithins

Lecithins are a mixture of acetone-insoluble phospholipids and other minor substances (triglycerides, carbohydrates, etc.). The most commonly processes used for lecithin modification are: fractionation by deoiling to separate oil from phospholipids, fractionation with solvents to produce fractions enriched in specific phospholipids, and introduction of enzymatic and chemical changes in phospholipid molecules. The aim of this work was to evaluate the emulsifying properties of different modified sunflower lecithins in oil-in-water (O/W) emulsions. In this study, five modified sunflower lecithins were assessed, which were obtained by deoiling (deoiled lecithin), fractionation with absolute ethanol (PC and PI enriched fractions), and enzymatic hydrolysis with phospholipase A₂ from pancreatic porcine and microbial sources (hydrolyzed lecithins). Modified lecithins were applied as an emulsifying agent in O/W emulsions (30:70 wt/wt), ranging 0.1–2.0% (wt/wt). Stability of different emulsions was evaluated through the evolution of backscattering profiles (%BS), particle size distribution, and mean particle diameters (D [3, 4], D [3, 2]). PC enriched fraction and both hydrolyzed lecithins presented the best emulsifying properties against the main destabilization processes (creaming and coalescence) for the analyzed emulsions. These modified lecithins represent a good alternative for the production of new bioactive agents.     

Emulsifier type,metal chelation and pH affect oxidative stability of n‐3‐enriched emulsions

Recent research has shown that the oxidative stability of oil‐in‐water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n‐3‐enriched oil‐in‐water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Tween resulted in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate‐stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA generally reduced oxidation, as evaluated by volatiles formation in all emulsions, irrespective of pH and emulsifier type, except in the lecithin and caseinate emulsions where a pro‐oxidative effect was observed for some volatiles. The different effects of the emulsifier types could be related to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical barrier around the oil droplets.     

The composition of the difficultly extractable soybean phosphatides

Summary The object of the present work has been to study those soybean phosphatides which cannot be extracted by means of nonpolar solvents but only be means of mixtures of nonpolar and polar solvents, for instance hexane and ethanol. These phosphatides were fractionated by the countercurrent distribution technique, and the following groups of substances were found: a) carbohydrates with d-inositol in the form of the methyl ether called pinitol; b) a number of nitrogen-containing substances, the nature of which is not as yet fully elucidated but which is perhaps merely decomposition products of proteins; c) a glyceroinositophosphatidic acid which contains equimolar quantities of glycerophosphoric acid and inositolmonophosphoric acid and phosphorus and fatty acids at a ratio of about 1 to 2; d) a high-molecular phosphatide acid; and e) a mixture of the three glycerophosphatides: phosphatidylcholine,-ethanolamine, and-serine.     

A fourier transform infrared spectroscopy study of the effect of temperature on soy lecithin-stabilized emulsions

The effect of temperature on soy lecithin-stabilized emulsions was studied using Fourier transform infrared spectroscopy (FTIR). Oil-in-water (o/w) 4% (wt/vol) soy lecithin emulsions were prepared in 6% (vol/vol) medium-chain triglycerides and 94% (vol/vol) water using a two-stage homogenizer set at a pressure of 3000 psig. Three types of emulsions were used in this study: emulsions containing Lecigran and Lecimulthin as emulsifiers and a control emulsion, with no emulsifier added. After preparation, the emulsions were cooled to 4°C, held at this temperature, and spectra were collected after 1 h. The emulsions and reference water were raised to room temperature (22°C) and held at that temperature for 1 h and the spectra collected. The temperature was raised 15°C over the temperature range of 22 to 82°C, and spectral data were collected similarly. The four regions used for this determination in the subtracted spectra of the emulsion were those contributing to -OH vibration, -CH₂ stretching, H-O-H bending vibrations, and P=O, C-O-C, and P-O-C vibrations. The control emulsion was greatly affected at temperatures other than room temperature. This was due to the lack of lecithin as an emulsifier, resulting in a destabilization of the emulsion with temperature increases. The vibrational peaks for the emulsion containing Lecimulthin were found to be lower than those for the emulsion made with Lecigran due to greater water bonding. The control had the highest peaks at the -OH regions because of reduced interaction at the oil-water interface. Both of the emulsions with phospholipids remained stable throughout the temperature range. FTIR is a potentially powerful tool that could be used in the rapid determination of emulsion stability in food systems by measuring emulsifier-water interactions.     

Emulsification properties of polyesters and sucrose ester blends II: Alkyl glycoside polyesters

Surface active properties such as surface and interfacial tension reductions and stability of oil-in-water (o/w) and water-in-oil (w/o) emulsions by alkyl glycoside fatty acid polyesters, a potential fat substitute, and emulsifier blends of alkyl glycoside polyesters and Ryoto sugar esters were investigated. Our results indicate that blending of lipophilic and hydrophilic emulsifying agents produces a synergistic effect on reduction of surface and interfacial tensions and may, in some cases, result in more stable emulsions. Alkyl glycoside polyesters may be suitable for w/o emulsions, such as margarine and butter, and their blends with hydrophilic emulsifiers will produce reduced calorie emulsifiers suitable for use in o/w emulsions, such as salad dressing. There appears to be great potential for using such emulsifier blends in food, cosmetics and pharmaceutical applications.     

Lecithin production and properties

Soy lecithins are important emulsifiers used in the food, feed, pharmaceutical, and technical industries. Native lecithin is derived from soybean oil in four steps: hydration of phosphatides, separation of the sludge, drying, and cooling. Such lecithin has both W/O and O/W emulsifying properties. Products with improved emulsifying properties can be obtained by modifications, involving mainly fractionation in alcohol, hydrolysis (enzymatic, acid, or alkali), acetylation, or hydroxylation. Careful processing is required to produce lecithins of a high chemical, physical, and bacteriological quality.     

Components of “soybean lecithin”

Summary The acetone-insoluble material from soybean “lecithin” has been fractionated by submitting alcohol-soluble and alcohol-insoluble portions to countercurrent distribution between hexane and methanol. The alcohol-soluble portion was found to contain lecithin, cephalin, and sugars or glycosides; the alcohol-insoluble portion was separated into two major inositol-containing phosphatides and sugars or glycosides. While the commonly accepted value of 30–35% for lecithin in the phosphatides was confirmed, it appears that the accepted value of 65% of cephalin needs revision. The approximate composition for one sample of soybean phosphatides is estimated to be 29% lecithin, 31% cephalin, and 40% inositol-phosphatides. Presented at the 39th Annual Meeting of the American Oil Chemists' Society, May 4–6, 1948, in New Orleans, Louisiana. This paper reports results obtained from a research project financed by the Research Marketing Act of 1946. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

稠油管输乳化降粘剂选择方法综述

简要介绍稠油乳化降粘管输的机理,并针对乳化降粘剂的选择方法进行总结概括。重点介绍了HLB法乳化剂筛选,HLB值判断,以及HLB计算方法。并从乳化降粘率、乳化剂的稳定性、乳化剂的流变性和乳化剂的破乳性能等方面进行评价O/W型乳状液,选择适配的乳化剂。     

Soybean “lecithin” and its fractions as metal-inactivating agents

Summary The addition prior to deodorization of 0.1% of either crude phosphatides, or the alcohol-soluble, or the alcohol-insoluble fraction all improved the oxidative stability and the initial flavor of soybean salad oil. However all three additives caused significant darkening of the oils and the introduction of undesirable storage flavors when added at levels which improved the oxidative stability. High-sugar fractions from the crude phosphatides did not darken the oil nor did they confer improved oxidative or flavor characteristics. Cadmium-precipitated lecithin and inositol-phosphatidic acids containing no amino nitrogen gave lower color to salad oils upon deodorization than did the amino-nitrogen-containing phosphatides. Purified cadmium-precipitated lecithin had little effect upon the oxidative stability when added at levels below 0.02%. A significant improvement results from the addition of 0.05%, and oxidative stability shows further improvement by raising the level to 0.1%; however no increase in stability was obtained by raising of the concentration above this level. At concentrations of 0.01 and 0.05%, cadmium-precipitated lecithin had little effect on the color of the oil. At levels of 0.1 and 0.2%, significant darkening of the oils occurred though much less than with the amino-nitrogen-containing phosphatides. Based on the flavor responses of oils to which these phosphatides were added, it appears that phosphatides constitute the precursors for the melony, bitter, cucumber flavors frequently encountered in aged soybean salad oils. These flavor responses are the same as those obtained from added phosphoric acid. Presented at fall meeting of American Oil Chemists’ Society, Nov. 2–4, 1953, in Chicago, Ill. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Service, U. S. Department of Agriculture.