Evaluation of eight extraction methods and their effects upon total fat and gas liquid chromatographic fatty acid composition analyses of food products

Samples of corn beef hash, frozen turkey pie, frozen beef pie, and beef stew were extracted by eight methods. Methyl esters of the fatty acids contained in the extracted fat residue were prepared with BF₃-methanol reagent and measured quantitatively by gas liquid chromatography. A 4N HCl digest followed by ethyl ether extraction was the most effective extraction method. Total lipid extracted, fatty acid distribution, and triglyceride recovery were the primary evaluation criteria. Recovery studies were carried out on eight different foods ranging from high meat content to pure vegetable shortening. Presented at the AOCS Meeting, New Orleans, May 1973.     

Fractionation of Gluten Lipids with Supercritical Carbon Dioxide

Gluten lipids are of two kinds, polar and nonpolar. Both groups consist of a large number of lipids. Gluten lipids can be extracted by conventional solvents as ethanol but also by supercritical carbon dioxide. The high density and the good mass transport properties make the supercritical fluid an excellent solvent. Ethanol extracted gluten lipids have been fractionated with supercritical CO₂ at different pressures and constant temperature. The extract contains triglycerides and free fatty acids, and a more concentrated fraction of polar lipids is left in the extraction vessel. While both polar and nonpolar lipids are soluble in ethanol, only nonpolar lipids are dissolved by supercritical CO₂. An addition of a small amount of ethanol to the CO₂, can, however, increase the solubility of the polar lipids.     

Lipids in wheat from various classes and varieties

Lipids were extracted with petroleum ether and with water-saturated n-butanol from 8 hard red winter, 5 hard red spring, and one each from soft red, durum, and club wheat varieties from 2 harvests. The butanol-extracted lipids were fractionated into nonpolar and polar lipids by silicic acid column chromatography, and the two major fractions were subfractionated by thin-layer chromatography. Durum wheats contained the highest lipid contents, and the highest concentration of nonpolar lipids. The breadmaking wheat varieties had a lipid content which was consistent for the 2 years examined. The total and nonpolar lipid contents of hard red spring wheats were higher than of hard red winter wheats. The polar lipid contents of wheats from the two classes were essentially equal. Total lipid contents were substantially higher in wheats than in flours milled from the wheats. Nonpolar lipids constituted about one-half of the flour lipids and two-thirds of the wheat lipids. Concentrations of triglycerides were higher in wheat than in flour nonpolar lipids. Glycolipids were present in comparable concentrations in wheat and in flour polar lipids; concentration in polar lipids of phosphatidyl choline was higher and of other phospholipids was lower in wheat than in flour polar lipids. No. 547, Kansas Agrieultural Experiment Station, Manhattan. Done in part under contract with the U.S. Department of Agriculture and authorized by the Research and Marketing Act of 1946. Supervised by the Western Utilization Research and Development Div., ARS.     

Lipid composition of beef and human pituitary glands

The lipid composition of beef and human pituitary was determined by chromatographic and spectrophotometric methods. Beef pituitary lipid contained about 25% nonpolar lipids and 75% phospholipids whereas nonpolar lipids made up approximately 60% of the total in human pituitaries. The main nonpolar (i.e., low polarity) lipids in human pituitary were triglycerides, cholesterol, free fatty acids and an unidentified component in the triglyceride fraction. Cholesterol was the major nonpolar lipid component in freshly collected beef anterior and posterior pituitary, but the amount of free fatty acids appeared to increase during storage. Preliminary investigation of the unknown nonpolar lipid in human pituitaries suggested that it was an unsaturated hydroxy compound with no carbonyl functions. Thin layer chromatography indicated that it was also present in smaller amounts in freshly collected beef pituitaries. The main phospholipids of beef anterior, posterior and human pituitary were phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl inositol, phosphatidyl serine and sphingomyelin. The fatty acid composition of total nonpolar lipids, free fatty acids, total phospholipids, phosphatidyl ethanolamine and phosphatidyl choline of beef anterior and posterior pituitary was determined by gas liquid chromatography. Mixtures of saturated and unsaturated fatty acids ranging from C₁₂ to C₂₂ were present; the main fatty acids were palmitic, stearic, oleic, linoleic and arachidonic.     

The lipid composition of wheat flours varying widely in bread-making potentialities

Lipids were extracted with petroleum ether (average 0.93%) and with water-saturated n-butanol (average 1.20%) from flours milled from composite 8 hard red winter, 5 hard red spring, and each from red soft, durum, and club wheat varieties. The butanol-extracted lipids were fractionated into nonpolar and polar lipids by silicic acid column chromatography, and the two major fractions were subfractionated by thin-layer chromatography. The extracted, washed, lipids contained about 52% nonpolar, and 48% polar lipids. Flours milled from durum wheat contained substantially less polar lipids, than flours milled from hard red winter or hard red spring wheats. The triglycerides constituted about 50% of the nonpolar lipids. Among the polar lipids, digalactosyl glyceride was the major component (about 40%); an unidentified compound, and a mixture of monogalactosyl glyceride with phosphatidic acid were about 20% each; and phosphatidyl ethanol amine, phosphatidyl choline and phosphatidyl serine comprised about 4, 7, and 4.5% of the polar lipids, respectively. Contribution No. 514. Kansas Agricultural Experiment Station, Manhattan. A report of work done in part under contract with the US Department of Agriculture and authorized by the Research and Marketing Act 1946. This contract was supervised by the W. Res. and Dev. Div., ARS, USDA.     

Total and polar lipids in soybean protein meals

Soybean protein meals obtained by various oil extraction methods have different neutral oil content, and they may contain differnet amounts of polar lipids. Three soy protein meals obtained by different processing methods were extracted by two solvents consecutively, chloroform/methanol (2:1, vol/vol) and water-saturated butanol, for total lipid analysis. The organic flour (i.e., ground soybean) containted 15.52% total lipids; the high protein dispersibility index flour from extrusion-expelling processing and the white flour from conventional solvent extraction contained 11.20 and 1.84% total lipids, respectively. Organic flour contained more polar lipids than the other two protein meals on a dry-weight meal basis. Chloroform/methanol extracted most of the lipid from the meals, whereas water-saturated butanol resulted in an extract with more polar lipids than that from chloroform/methanol extraction.     

Lipid composition of oats (Avena sativa L.)

Compositions of lipids extracted from a sample of Hinoat oat by seven solvent systems and that extracted with chloroform/methanol (2:1 v/v) from six selected cultivars representing high and low lipid contents are reported. Lipid components (steryl esters, triglycerides, partial glycerides, free fatty acids, glycolipids and phospholipids) were separated by silicic acid column chromatography and thin layer chromatography and quantitated by GLC analysis of fatty acids and phosphorus determinations. Twelve oat cultivars were examined for the fatty acid composition of lipid extracted with n-hexane. Lipids extracted from Hinoat by different solvent systems ranged from 5.6 to 8.8%. Quantitative distribution of lipid components extracted with chloroform/methanol from six cultivars containing 4.6 to 11.6% lipid showed a significant correlation (γ=0.99) between the total lipid and the neutral lipid content. Phospholipid content was similar in all cultivars, but glycolipids showed a two-fold increase in high lipid oats. Triglycerides contained less palmitic and more oleic acid than the glycolipids or phospholipids. Nine glycolipids and 11 phospholipids have been identified, and the polar lipid composition of Hinoat oat is presented.     

The lipids of corn germ and endosperm

Mature kernels of an inbred corn were hand dissected into germ and endosperm fractions. Among various solvents tested, boiling, water-saturatedn-butanol extracted the most lipid from endosperm, and it was used as t h e extracting solvent for both germ and endosperm. The germ contained 78% of the total lipids and the endosperm 17%. The most striking differences in the fatty acid compositions of the triglycerides and polar lipids were higher levels of stearic and linolenic acids in the endosperm lipids. Although precautions were taken during extraction to inactivate lipases, immediately after harvest the free fatty acid level of the total lipids of the whole kernel was 6.5%. Ninety-five percent of the free fatty acids was in the endosperm fraction where the free fatty acids made up 36.5% of the total lipids. In germ, free fatty acids represented only 0.6% of the total lipids. The individual phospholipid and glycolipid classes of the endosperm and germ lipids were similar except for high levels of lyso compounds in the endosperm lipids. The higher levels of linolenic acid, free fatty acids and lyso lipids in endosperm may affect the keeping quality of the corn grain and of fractions milled from the endosperm. Presented at the AOCS meeting, St. Louis, May 1978.     

不同亚临界溶剂从微拟球藻湿藻泥中提取油脂

以微拟球藻(Nannochlorsis sp.)湿藻泥为原料,研究了亚临界乙醇、亚临界乙醇-正己烷共溶剂及硫酸辅助亚临界乙醇-正己烷共溶剂3种萃取体系对微藻油脂提取的影响. 结果表明,亚临界乙醇-正己烷比亚临界乙醇对湿藻细胞有更高的油脂萃取率和低的溶剂用量,加入少量硫酸可进一步提高油脂的提取率、降低溶剂用量. 微拟球藻湿藻泥(含水约70%)优化提取条件为,正己烷/乙醇体积比3:1,液固比(溶剂/藻细胞干重)7 mL/g,加入藻细胞干重6%的硫酸,1.5 MPa下90℃萃取30 min,在此条件下油脂提取率可达90%以上. 3种萃取体系获得的微藻油脂均以甘油三酯为主,甘油三酯的脂肪酸主要为C16:0, C18:1和C16:1,其中硫酸辅助亚临界共溶剂萃取的微藻油脂中甘油三酯含量最高,约占总脂的86%以上.     

Extraction of lipids from a specialist dairy stream

In this work a process for the extraction of neutral and complex lipids from the specialist dairy stream ‘beta-serum’ is described. Beta-serum is a proprietary product obtained from dairy streams containing greater than 60% fat that have been through phase inversion from an oil-in-water to a water-in-oil emulsion. It is an enriched source of milk fat globular membrane proteins and complex lipids, and is distinct from buttermilk in this respect. In the process described here a total lipid extract could be obtained from liquid beta-serum using a continuous near-critical dimethyl ether (DME) antisolvent fractionation process. Protein and water are precipitated from solution when mixed with the DME, whilst lipid and some water are extracted into the DME-rich phase. The extraction yield of lipids depended on the solids content of the feed and the feed to DME flow ratio, but did not depend on the lactose content. Lipids were also extractable from spray dried beta-serum powder, but only when the lactose content had been reduced below 45% by mass. A two step extraction process is described in which neutral lipids are extracted with supercritical CO₂, and then polar lipids using near-critical DME. The polar lipid extract was enriched in phospholipids (∼70% by mass), which included phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin. Other complex lipid components extracted included gangliosides and cerebrosides. Unlike the antisolvent process, proteins were not denatured during either CO₂ or DME processing of the spray dried powders, and the de-fatted powders are therefore suitable for a range of functional foods. A polar lipid extract could also be produced from spray dried powder by extracting first with DME to obtain a mixed neutral/complex lipid extract, then re-extracting the lipid extract with CO₂ to remove neutral lipids.     

Lipids extracted from soy products by different procedures

Lipids in soybean defatted meal, concentrate and isolate were extracted by four procedures: (a) a Soxhlet extract by chloroform-methanol; (b) a Soxhlet extraction by benzene/ethanol; (c) a short extraction by chloroform/methanol; and (d) a short extraction by hexane/ethanol. Procedure 2 extracted more lipid than Procedure 1 from the isolate and meal. Both Soxhlet procedures extracted more lipid than Procedure 3 from the meal only, and more lipid than Procedure 4 from all products. Percent lipid on dry matter basis ranged for the meal, 1.56 to 4.52; concentrate 0.90 to 1.44; and isolate, 0.28 to 0.96. Lipids extracted from each product by Procedures 3 and 4 were fractionated quantitatively into (a) neutral lipids, (b) polar lipids except lecithin, and (c) lecithin. Fatty acid (C12–C20) composition of each lipid fraction was determined, and attempts were made to identify lipids. The larger amount of lipid in any product extracted by either Procedure 3 or 4 was in Fraction 1. Linoleic acid was the most abundant acid found in any lipid fraction. Significantly more oleic acid was found in Fractions I and II Concentrate lipids than in the same fractions of meal or isolate lipids. A number of lipids were found in Fractions I and II, but the only lipid in Fraction III was lecithin.     

Surfactants as replacements for natural lipids in bread baked from defatted wheat flour

Petroleum ether (PE) extracted 1.00% total free lipids (0.70% nonpolar and 0.30% polar) and 2-propanol (PrOH) extracted 1.36% total free and bound lipids (0.73% nonpolar and 0.63% polar) from wheat flour; the lipid fractions were characterized by thin layer chromatography. PE- or PrOH-defatted flours were baked after reconstitution with total, nonpolar, or polar wheat flour lipids; or with equivalent amounts of nonionic sucrose monopalmitate (SMP), ethoxylated monoglycerides (EMG) — each with a hydrophile-lipophile balance (HLB) of 14.0 or anionic sodium stearoyl-2-lactylate (SSL) — with an HLB value of 9.0. Defatted flours supplemented with surfactants alone or in combination with wheat flour lipids were used in bread with no-shortening and with 3%-shortening. The importance of the polar flour lipids in breadmaking was verified. The lipids in wheat flour were essential for maximizing the beneficial effects of shortening on breadmaking quality. Nonionic SMP or EMG completely replaced both PE-extractable wheat flour free total lipids ( or their non-polar or polar fractions) and 3% shortening; nonionic surfactants with high HLB were better than the anionic SSL for replacing free flour lipids. No surfactant completely replaced unfractionated PrOH-extracted lipids (free + bound) and shortening or total polar flour lipids (free + bound). All surfactants, especially anionic SSL, added with PrOH-extracted polar lipids improved the overall bread-making properties of the PrOH-defatted flour both in the absence and in the presence of shortening. Presented at the AOCS Meeting, New York, May 1977     

Study of free and bound lipids ofBrassica campestris,var yellow sarson

Mature seeds ofBrassica campestris var. yellow sarson were extracted with hexane to yield free lipid. The residue then was extracted with chloroform-methanol to release bound lipid. Free and bound lipids were separated into polar and nonpolar fractions chromatographically. The nonpolar fraction of both free and bound lipid consisted mainly of triglycerides with small amounts of steryl esters, free sterols, mono- and di-glycerides, and free fatty acids. The principal components of polar bound lipid were phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol, and steryl glycoside. In the free polar lipid, there was more phosphatidyl inositol and less phosphatidyl choline and phosphatidyl ethanolamine. Erucic acid content was much greater in the nonpolar fractions and in the polar free lipid than in the polar bound lipid.     

Physicochemical Properties, Volatile Compounds and Phospholipid Classes of Silver Carp Brain Lipids

Large amounts of utilizable by-products are produced concomitant with silver carp processing. The lipids from fish brain contain considerable essential fatty acids which however have seldom been studied. In this study, the lipids extracted from the brain of silver carp exhibited good physicochemical properties. Forty volatile compounds were identified, of which hydrocarbons and aromatics predominated. The ratios of polar lipids and phospholipids to total lipids were 22.73 and 10.95 % respectively. Phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) accounted for 83.9 % of the phospholipids. Major fatty acids of neutral lipids, polar lipids, PC, PE and PS differed significantly. PE had the most polyunsaturated fatty acids (PUFA), while PC, PE and PS were rich in docosahexaenoic and eicosapentaenoic acids. Moreover, the ratios of fatty acids were considered to be reasonable due to high levels of n3 PUFA. The lipids from silver carp brain have been demonstrated to be healthy and nutritious. The results herein confirm that silver carp brain lipids are a commercially and industrially feasible prospect.     

Embryonic fatty acid composition as a function of yolk fatty acid composition in eggs of the lesser spotted dogfish (Scyliorhinus canicula L.)

Yolk and embryonic total lipids were extracted from spotted dogfish eggs at two developmental stages. Total lipids were fractionated into neutral lipids (NL) and polar lipids (PL), and the fatty acid composition of each group was determined. Yolk lipid composition was found to be quantitatively different (NL/PL≊1) from embryo lipid composition (NL/PL≊0.5), for both stages of development. However, individual fatty acid composition did not differ from younger to older eggs for either yolk or embryo. There were significant differences (p<0.05) in major fatty acid groups from yolk and embryonic PL for saturated fatty acids, monounsaturated fatty acids (MUFA) and n−3 polyunsaturated fatty acids (PUFA) for younger eggs, and for MUFA and n−3 PUFA for older eggs. For NL, only MUFA composition from the oldest eggs showed differences between yolk and embryo. Results are discussed in terms of embryonic needs for highly unsaturated fatty acid (HUFA) biosynthesis, as well as to provide some explanations for the unusually high levels of 20∶4n−6 in both yolk and embryonic neutral lipids and polar lipids.     

Lipids of maturing grain of corn (Zea mays L.): I. Changes in lipid classes and fatty acid composition

The total lipids of the grain from three strains of corn were compared throughout the growing season. The Illinois High Oil stock and the two inbreds, H51 and K6, represented high, intermediate and low oil-producing lines. In all three strains lipid synthesis was most active between 15 and 45 days after pollination. The lipids were extracted from the grain with a mixture of chloroform, methanol and water and were separated into classes by silicic acid and thin layer chromatography. Triglycerides constituted 10–17% of the total lipids at 10 days after pollination and increased to 75–92% at 75 days. Polar lipids at 10 days represented 70–72% and at 75 days 4–21%. Fatty acid compositions of the triglycerides and polar lipids changed as the grain matured, but the fatty acids of the polar lipids were more saturated than those of the triglycerides throughout the sampling periods. The major polar lipids were digalactosyl diglyceride, monogalactosyl diglyceride, phosphatidyl choline, phosphatidyl inositol and phosphatidyl ethanolamine. Presented in part at the AOCS-AACC Joint Meeting, Washington, D.C., April 1968.     

Tissue culture of cocoa bean (Theobroma cacao L.): changes in lipids during maturation of beans and growth of cells and calli in culture

Callus cultures ofTheobroma cacao L., initiated from explants of immature cocoa bean cotyledons, contained 5.3%–6.4% lipids (dry wt basis). The major fatty acids were palmitic, oleic and linoleic acids. Cell suspensions contained 5.7–7.7% total lipids which had a higher polyunsaturated fatty acid content than total lipids of the calli. Phospholipids and glycolipids were the predominant lipid classes of calli and cell suspensions. Immature cocoa beans at early stages of development contained much higher polyunsaturated fatty acids, higher polar lipids and lower triglycerides than did mature ripe beans. Ripe cocoa beans contained 54% total lipids of which 96.8% where triglycerides. The fatty acid composition of total lipids of calli and cell suspensions were similar to those of the immature cocoa beans.     

Polar and nonpolar lipids and their fatty acid composition of a fewFusarium species

A few species ofFusarium have been evaluated for their potential to produce lipids. The isolates under investigation exhibited wide variation with respect to the mycelial weight, total lipid content and percentage composition of polar and nonpolar lipids in which triglycerides were the major components (81–90%). Palmitic, stearic, oleic and linoleic acids were the major fatty acids in both the fractions. The polar lipids contained higher levels of linoleic acid, whereas nonpolar lipids contained oleic acid as the predominant acid. Nonpolar lipids were more saturated than polar lipids.     

Total,polar and neutral lipids ofRhizopus arrhizus fischer

The changes in total lipid content, neutral and polar lipids, total fatty acids, and free fatty acids were investigated over a 4 day period in the zygomycete,Rhizopus arrhizus Fischer. The highest concentration of lipids occurred at the 72 hr period. The degree of unsaturation in the total fatty acid fraction increased during the growth period, whereas the degree of unsaturation decreased in the free fatty acid fraction during the same time period. The ratios of neutral to polar lipids over the 4 day period were: 0.75, 0.22, 1.94 and 0.94. The major components of polar lipids were phosphatidyl ethanolamine, lecithin, lysolecithin, and fatty acids. The fatty acids in the mono- and diglycerides were predominately saturated (67–96%). The fatty acids in the triglycerides shifted from a predominately unaturated (69%, 24 hr) to a more saturated pattern (62%, 96 hr).     

Lipid extraction from natural plant source of Adenanthera pavonina using mixed solvent by superheated extractor

The lipid content was extracted from the saga seed by superheated condition and soxhlet apparatus. The mixture of hexane, chloroform and methanol was utilized as a mixed solvent for these extraction operations. Different parameters such as different solvent, temperature, mean particle size and solvent flow have been examined. The optimized lipid extraction was achieved as 26.2 wt% by using superheated condition from the saga seed powder at 90 °C for 120min. Then the fatty acids profile of the optimized Adenanthera pavonina oil were analyzed by gas chromatography. Unsaturated fatty acid was high as 83.7% compared with saturated fatty acid barely 15.4% by relative.