Changes in the lipid and fatty acid composition during maturation of seeds of white mustard (Sinapis alba)

The oil content of the seeds of white mustard (Sinapis alba) was determined 3 weeks after flowering and at weekly intervals until seeds were matured. Examination of the lipid classes by quantitative t.l.c. showed that triglycerides were the major components at all stages and were accompanied by sterol esters, diglycerides and polar lipids; monoglycerides were only detected in the first 2 samples. The fatty acid composition of the total oil and the mono-, di- and triglycerides and sterol esters was determined by g.l.c. The 7 major fatty acids, namely palmitic, stearic, oleic, linoleic, linolenic, eicosenoic and erucic acids were present at all stages of maturity. The fatty acid composition of the triglyceride fraction was similar to that of the total oil whereas the mono- and diglycerides and sterol esters contained a relatively higher proportion of saturated fatty acids. Erucic acid, the major acid of the oil from mature seeds did not become the major acid until 35 days after flowering. The results are discussed in relation to pathways of lipid synthesis in higher plants.     

Mesocarp,seed and pollen lipids of Raphia palms

The lipid classes, fatty acids and sterols of the mesocarp, seed and pollen lipids of five species of Raphia palms endemic to Nigeria were analysed. Apart from quantitative differences in the fatty acid compositions, chromatographic analyses demonstrated very little change in the patterns of the characteristic lipids associated with either the mesocarps, seed endosperms or pollens. Mesocarp lipids contained mainly triglycerides, while palmitic, oleic and linoleic acids were the major acids. Contrary to published data for seed lipids, Raphia seed endosperms contained a relatively small amount of triglycerides and a high proportion of polar lipids. Fatty acids associated with this tissue were not only highly unsaturated, but were significantly different from typical fatty acids of seed lipids. Raphia pollens, on the other hand, showed a complex array of lipid types. Triglycerides, sterols and sterol esters constituted the main neutral lipids while phosphatidyl choline, phosphatidyl inositol, phosphatidyl ethanolamine and galactosyl diglycerides represented the polar fraction. Apart from minor trends, palmitic, oleic and linoleic acids constituted the major fatty acids in all species. The biological importance of the steroidal sapogenins found in all organs is discussed.     

Effect of crop maturity on leaf lipids

Studies extending throughout a period of 100 days' growth have been made on the total lipids of ryegrass, kale and fodder radish. Expressed in terms of % dry matter, lipids are at a maximum of about 10 to 11% during the period of vegetative growth. Lipid yields in absolute terms are maximal at 200–300 kg/ha after 56 to 70 days from sowing, at which stage lipids have fallen to 7 to 9% of total dry matter, according to species. Considering the fatty acids as a whole, dominant components are linolenic and palmitic, the latter rising and the former falling as maturation progresses. Minor fatty acids show no clear trend. More specific changes in fatty acid profiles are revealed when individual lipid classes are studied separately. Lipid classes display a predictable change in pattern as maturation progresses. New growth is rich in partial glycerides and free sterols, and particularly in mono- and digalactosyl diglycerides and sulphoquinovosyl diglyceride. Leaves from mature or senescing crops show progressive falls in these components, accompanied by the appearance of triglycerides, free fatty acids and steryl glycosides. In the case of fodder radish the accumulation of the hydrocarbon, n-nonacosane, is a noteworthy feature. The principal phospholipids do not change appreciably with maturation. The trends observed on maturation show common general patterns for all the leafy crops so far studied. They do emphasise, however, the crucial importance of specifying both species and duration of growth when quoting data on leaf lipid compositions.     

Oxidation of free and esterified linoleic and linolenic acids in bread doughs by wheat and soya lipoxygenases

Lipids containing ¹⁴C-labelled linoleic and linolenic acids were added to flour which was then made into bread doughs with or without 2% enzyme-active soya flour. The ¹⁴C-labelled lipids and their oxidation products were analysed as intact lipids or as ¹⁴C fatty acid methyl esters by thin-layer chromatography. In the control doughs wheat lipoxygenase oxidised free fatty acids and monoglycerides. In doughs containing soya flour, steryl esters, triglycerides, diglycerides, mono-galactosyl diglycerides, digalactosyl diglycerides and phosphatidyl choline were also oxidised, and the oxidation of these lipids is attributed to soya lipoxygenase.     

Effect of processing and storage on neutral lipids of buffalo meat

Three muscles viz. Triceps brachii (TB), Longissimus dorsi (LD) and Biceps femoris (BF) from different anatomical locations of adult male buffaloes were stored after broiling and pressure cooking under refrigerated (4°C) condition for 3, 6, 9 days and 30, 60, 90 days under frozen (-10°C) storage. At the end of each storage interval they were analysed for total lipids, cholesterol contents and glyceride fractions i.e. monoglycerides (MG), diglycerides (DG), and triglycerides (TG). Muscles differed significantly in total lipids as well as contents of all glyceride fractions. Muscle LD had significantly higher total lipid content than TB and BF. Muscles differed significantly in their esterfied cholesterol (EC) contents. Heat processing increased total lipids, cholesterol, MG, DG and TG contents of all the buffalo muscles studied. Total cholesterol contents remained unchanged during refrigerated and frozen storage. However, EC, MG, DG and TG contents declined during storage. The influence of anatomical locations on fatty acid composition of neutral lipids was observed. The ratio of unsaturated to saturated fatty acids increased due to cooking. A gradual decrease in mono- and polyunsaturated fatty acids was recorded during refrigerated and frozen storage.     

Identification and quantitative determination of the lipids of dried Origanum dictamnus leaves

The Origanum dictamnus plant was examined for its lipid and fatty acid compositions. A combination of chromatographic techniques has been employed for the qualitative and quantitative determination of the lipids of dried leaves of O. dictamnus. The following polar lipids were identified: mono-, di- and poly-digalactosyl diglycerides, sulpholipids, cerebrosides, phosphatidyl-ethanolamine, phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, phosphatidyl choline and phosphatidic acid. The non-polar lipids identified were sterols, steryl esters, fatty alcohols, free fatty acid, waxes, traces of triglyceride, triterpenic acids and essential oil. The predominant fatty acids were palmitic, oleic and linoleic acids.     

LIPIDS OF BARLEY,MALT AND ADJUNCTS

Barley contains up to 4·4% of its dry weight as lipid when measured as total fatty acid. Commercial malts can contain up to 3·4% lipid and the proportions of the constituent fatty acids are similar to those of barley. About 70% of the fatty acids of barley and malt are present as triglycerides whilst up to 8% of the lipids in malt are found as free fatty acids. Germination results in a fall of up to 30% in the lipid content, mainly due to the hydrolysis of triglycerides and metabolism of the released fatty acids. The immediate products of triglyceride breakdown, namely fatty acids and mono- and diglycerides, do not accumulate in malt to any significant extent. Common brewing adjuncts contain up to 4% lipid.     

Lipid changes during germination of fenugreek seeds (Trigonella foenum-graecum)

Fenugreek seeds were germinated in the dark for 96 h. Total lipid extracts were prepared and found to decrease on germination. Ultraviolet, visible and infra-red spectra were estimated for the lipids of ungerminated and germinated fenugreek seeds. Free fatty acids (FFA), total chlorophyll and carotenoid pigments increased greatly after germination. On the other hand, triglycerides, phospholipids and unsaponifiable matter decreased. Determination of individual phospholipids showed that phosphatidylcholine (PC) and phosphatidylethanolamine (PE) constitute about 67% of the total phospholipids of ungerminated seeds. After germination PC and PE decreased whilst phosphatidic acid (PA) and phosphoglyceric acid (PG)—degradation products of phospholipids by phospholipases—increased. The fatty acid composition showed that the total unsaturated fatty acids decreased whilst the total saturated fatty acids increased on germination. The fatty acids 18:2 and 18:3 were the most abundant acids in the lipids of the ungerminated seeds and fell after germination from 41·2% to 31·8% and 23·2% to 14.4%, respectively. The minor constituent fatty acids 20:0, 22:0 and 20:1 increased by 3·3-, 3·0- and 7·8-fold, respectively after germination.     

EFFECT ON SEMLIKI FOREST VIRUS AND COXSACKIEVIRUS B4 OF LIPIDS COMMON TO HUMAN MILK

A lipid-enveloped virus (Semliki Forest virus: SFV) and a nonenveloped virus (coxsackievirus B4) were treated with neutral lipids known to be present in human milk or able to be generated by lipase activity in human milk. Triglycerides and diglycerides were inactive compared to monoglycerides and free fatty acids which were active against SFV (90% inactivation) at concentrations as low as 0.7 μM. Of the compounds tested monolinolein was the most active against SFV. None of the lipids tested were active against coxsackievirus B4. A synthetic milk (Almiron-M2), high in unsaturated triglycerides, was inactive against either virus.     

Fumgal lipids. I. Effect of different nitrogen sources on the chemical composition

The effect of three nitrogen sources on the chemical composition of seven fungi, namely: Aspergillus niger, A. luchuensis, Penicillium crustosum, Alternaria tenuis, Rhizoctonia solani, Mucor sp. and Pythium irregulare has been studied. The various fungi showed a great variation with respect to lipid percentage and total lipid content. Lipid content varied from 3.2 to 41.5%. Non-polar lipids were comprised of monoglycerides, diglycerides, free sterols, free fatty acids and triglycerides. The quantitative make-up of the non-polar lipid varied with different nitrogen sources. Palmitic, stearic, oleic and linoleic acids were the major fatty acids while lauric, myristic, palmitoleic, linoleic and arachidic were the minor ones. The fatty acid composition was dramatically changed by changing the nitrogen source. Since different fungi responded differently to changes in nitrogen source, no generalisation could be made. Two-dimensional thin-layer chromatography of the polar lipid fraction of these fungi revealed the presence of a maximum of fifteen spots. Phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl inositol were the major spots while lysophosphatidyl choline, lysophosphatidyl ethanolamine and phosphatidyl glycerol were present in smaller quantities. In comparison to phospholipids, glycolipids (except sterol glycoside) were present in relatively lower concentration. Pythium irregulare was very characteristic in having no glycolipids at all.     

Changes in flour lipids during the storage of wheat flour

High- and low-grade spring and winter wheat flours of ～13% moisture were stored at 15, 25 and 37 °C and the lipids were then extracted with water-saturated n-butanol. In the original (control) flours there were more neutral lipids and glycolipids in low-grade winter than in high-grade winter and in low-grade spring than in high-grade spring flours, but there were no corresponding differences in the amounts of phospholipids. The total extractable lipid contents of the flours remained constant in the samples stored at 15 °C, but there were slight losses in the samples stored at 25 and 37 °C. Total lipid contents determined by acid hydrolysis remained constant in all cases indicating that no loss of fatty acids had occurred on storage. There was sufficient hydrolysis of all glycerides to account for the increased amounts of free fatty acids in the stored flours. Some complete deacylation of lipids to free fatty acids and water-soluble products was indicated. The fatty acid composition of all lipids remained constant, and there was no evidence of any lipoxygenase or other enzymic degradation of fatty acids. Stereoanalysis of the principal glycerides indicated that phosphatidylcholine (and probably also phosphatidylethanolamine) was specifically hydrolysed at the 2-position, presumably by phospholipase-A₂. Hydrolysis of triglycerides, diglycerides and monoglycerides was attributed to the action of wheat and microbial lipases of unknown specificity. Stereoanalysis of N-acylphosphatidylethanolamine and the galactosyldiglycerides was not attempted, but it was deduced that they were randomly hydrolysed at the 1- and 2-positions. The changes found in the flour lipids differed from those reported to occur in germinating wheat and in stored damp wheat flour which had been damaged by moulds.     

An Investigation into the Lipid Classes of Skipjack Tuna (Katsuwonus pelamis)

The lipid classes of the muscle of Skipjack tuna (Katsuwonus pelamis) were investigated over a period of 10 months by thinlayer chromatography. Triglycerides, diglycerides, monoglycerides and phospholipids content varied between 48.36 ± 1.22% and 62.49 ± 3.40%; 20.04 ± 5.59 and 28.53 ± 4.50; 0.98 ± 0.20% and 4.84 ± 2.48% and 4.31 ± 0.96% and 9.26 ± 0.52%, respectively. Both triglycerides and diglycerides formed the major fractions (between 68 and 91%) of Skipjack muscle lipid. There was a good concentration of phospholipids. Free fatty acid levels were fairly low and varied between 0.62 ± 0.10% and 3.94 ± 0.31%. No levels of hydrocarbons were detected in lipid samples from May to September but fairly high levels of (14.97 ± 2.89% and 12.74 ± 2.68, respectively) were detected in November and January samples.     

Effect of irrigation on lipid biosynthesis in maturing sunflower seeds

The effect of irrigation on lipid biosynthesis in maturing sunflower (Helianthus annuus L.) seeds has been studied. Restricted irrigation adversely affected the biosynthesis of polar lipids during initial stages and triglycerides at the later stages of seed development. The fatty acid composition remained unaffected by irrigation. A de novo synthesis of triglycerides and fatty acids has also been observed.     

Bestimmung von Mono-, Di- und Triglyceriden mit HPLC

The determination of monoglycerides, diglycerides and triglycerides in the normal phase system: Separon SGX-CN (silica gel with phase-bonded cyanoethyl) and mobile phase hexane-isopropanol-formic acid by HPLC with refractometric detection, is described. It was found that the separation was according to the molecular mass of glycerides, i.e. in groups. This was demonstrated with palmitic, oleic and linoleic acids. The diglycerides and especially monoglycerides of olive and sunflower oils were partly separated according to the ECN¹ values of the glycerides. The response factors related to triglycerides were estimated for the glycerides of the fatty acids and oils mentioned above. The value of response factors depends on the number of double bonds of the fatty acids.     

Changes in gross chemical composition with emphasis on lipid and protein fractions during germination of fenugreek seeds

Germination of fenugreek seeds for 3 and 5 days increased moisture, crude protein, crude fibre, non-protein nitrogen and ash contents, but total lipids and carbohydrates were decreased. Marked increases of Na and P, as well as Mg and Zn were observed. Triacylglycerols decreased continuously and this was accompanied by an increase in free fatty acids, monoglycerides, sterolesters and polar lipids. Albumin was the major protein fraction followed by globulin, glutelin and prolamin. Germination increased glutelin and non-protein nitrogen; the other fractions were decreased. The protein in vitro digestibility was improved after germination. PAGE showed a marked dissociation of albumin and globulin fractions after germination.     

Neutral Lipids Present in Starch of Uruchi and Mochi Rice

The total lipid contents of rice starch were 1.30 and 0.92%, and the ratios of neutral lipid to polar lipid were 56:44, and 77:23 in the case of Urichi and Mochi, respectively. The main classes of neutral lipids were free fatty acids, triglycerides, free sterols and sterolesters. The major components of free fatty acids and triglycerides were linoleic, palmitic and oleic acids. Among the component fatty acids of rice starch triglycerides, palmitic acid occupied almost exclusively 1-C and 3-C positions, 2-C position was rich in linoleic acid, and oleic acid was equally distributed in 1-C, 2-C and 3-C positions. The fatty acids in Uruchi triglycerides were symmetrically distributed in 1-C and 3-C positions, but Mochi triglycerides were of asymmetrical distribution. There was no appreciable difference in the sterol compositions of free sterols and sterolesters.     

Characterization of the Lipid Fraction in Lamb Meat: Comparison of Different Lipid Extraction Methods

The aim of this study was to evaluate the performance of four different extraction methods commonly used to quantify the intramuscular lipid content in meat: the Association of Analytical Chemists (AOAC) method (reference method) and methods based on the use of a solvent mixture with different polarities, such as chloroform–methanol described by Folch et al. (J Biol Chem 226:497, 1957) and Christie (1989) or hexane–isopropanol described by Hara and Radin (Anal Biochem 90:420, 1978). The following parameters were taken into account: lipid content; relative proportions of neutral and polar lipids; fatty acid composition of total, neutral, and polar lipid fractions; and phospholipid composition. The use of a combination of solvents with different polarities (Hara–Radin, Folch, and modified Folch methods) was more effective in extracting intramuscular lipids than the use of a single solvent (AOAC, reference method). The Hara–Radin method provided a cleaner lipid extract with a significantly higher content of total fatty acids than that obtained with the Folch and modified Folch methods. The lower polarity of the hexane–isopropanol mixture allowed us to obtain an extract richer in neutral lipids (triglycerides and diglycerides) and thus in saturated and monounsaturated fatty acids. The percentage distribution of individual fatty acids in the neutral lipid fraction was generally not affected by the extraction method adopted, while lipid obtained with both the Hara–Radin and Folch methods had a polar fraction with a higher percentage of polyunsaturated fatty acids. The use of the Hara–Radin method provided a polar fraction with less nonlipid material and lower phospholipid degradation.     

EFFECT OF POSTMORTEM AGING ON CHICKEN MUSCLE LIPIDS

Neutral lipids of fresh chicken breast muscles are shown to be triglycerides, sterols and sterol esters with only traces of mono- and diglycerides and free fatty acids. Phospholipids include measurable quantities of phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serine, sphingomyelin, diphosphatidyl glycerol, lysophosphatidyl choline and lysophosphatidyl ethanolamine. Fatty acid analyses of several of the lipid fractions are also included. Decreases in phosphatidyl choline and phosphatidyl ethanolamine coupled with increases in lysophosphatidyl choline, lysophosphatidyl ethanolamine and free fatty acids after 48 hr postmortem in the cold indicate phospholipase A activity concurrent with other postmortem changes. The significance of the results is discussed.     

SPECIFICITY OF LIPOLYSIS DURING DRY SAUSAGE RIPENING

The amounts of total and individual fatty acids present in tri-glycerides (TG), free fatty acids (FFA), diglycerides (DG), monoglycerides (MG) and polar lipids (PL) were determined at various stages of dry sausage ripening using a combination of thin layer and gas chromatography. Total FFA increased from 1 to 5% of total fatty acids and DG fatty acids from 0.5 to 4%, whereas TG fatty acids showed a corresponding decrease. The rate of liberation of FFA was in the order 18:2 > 18:1 > 18:0 > 16:0 while MG and DG were enriched in 16:0. These results suggest specificity of lipolysis.     

Changes in lipid composition and fatty acid profile of Nham,a Thai fermented pork sausage,during fermentation

Changes in lipid composition and fatty acid profile of Nham during fermentation were investigated. Total lipids of Nham were in the range 2–3%. The extracted lipid of initial Nham mix consisted mainly of triglycerides (TG), accounting for more than 75% of the total lipid, followed by phospholipids (PL) and a trace amount of diglycerides (DG) and free fatty acid (FFA). During fermentation, TG, DG and PL decreased with a concomitant increase in FFA, indicating lipolysis of Nham lipids during fermentation. Changes in fatty acids of the total lipids, non-polar and polar lipid fractions were observed during fermentation. In both total and non-polar lipid fractions, the major fatty acids found in a descending order were oleic (C18:1), linoleic (C18:2) and palmitic (C16:0) acids, which together accounted for 90% of the total fatty acids. Increases in fatty acid contents in both total and non-polar lipid fractions, were observed with a corresponding decrease in the quantity of fatty acids of phospholipids. As the fermentation proceeded, peroxide value generally increased while TBARS values decreased. Overall, lipid oxidation in Nham occurred during fermentation but did not cause the objectionable odour and taste in any Nham tested.