Asmo Kemppinen

Regiospecific determination of short-chain triacylglycerols in butterfat by normal-phase HPLC with on-line electrospray-tandem mass spectrometry.

This study uses normal-phase HPLC with on-line positive ion electrospray mass spectrometry (ESI-MS) to obtain quantitative compositional data on both synthetic and butterfat short-chain TAG. The product ion tandem MS of standards averaged 11.1 times lower in abundance of the ion formed by cleavage of FA from the sn-2-position for the pairs of regioisomers in the TAG classes: L/L/S-L/S/L and L/S/S-S/L/S, where L denotes long and S short acyl chain (C2−C6). The molar correction factors, determined for 42 regioisomeric pairs of short-chain TAG of 20 randomized mixture of standards, differed by 1.4–80% as the ratios varied between 0.217 and 5.847. Butterfat TAG were resolved into four fractions on short flash chromatography grade silica gel columns. Pairs of regioisomers in the TAG classes L/S/S-S/L/S with predominance of L/S/S isomers and the sole regioisomers in the TAG classes L/L(M)/S were identified by tandem MS, where M denotes either 8∶0 or 10∶0 acyl chain. The total proportion of L/L(M)/S isomers was estimated at 34.7 and that of L/S/S-S/L/S at 1.0 mol%, including a small proportion of S/S/S. In contrast to previous work, the present data indicate the presence of a small proportion of butyric and caproic acids in the sn-1-position. The overall distribution of the FA in the short-chain TAG of butterfat, calculated from direct MS measurements, was consistent with the results of indirect determinations based on stereospecific analyses of total butterfat.

Mass spectrometric identification of triacylglycerols of enzymatically modified butterfat separated on a polarizable phenylmethylsilicone column

Original butter oil, butter oil interesterified withPseudomonas fluorescens lipase as catalyst, and the saturated, monoene, diene and triene fractions of interesterified butter oil from silver ion chromatography on ap-propylbenzene sulfonic acid column were analyzed on a polarizable phenyl(65%)methylsilicone column. Major and also some minor molecular species of triacylglycerols (TG) were identified from the electron-impact (EI) gas chromatography/mass spectrometry analytical data for the original and lipase-modified butter oil and the four fractions. Acyl + 74 and acyl + 128 fragments of EI mass spectral data proved useful, in addition to acyl and M - RCOO fragments, in the identification of molecular species of TG. The TG compositions of the modified butter oils were compared with the composition calculated according to random distribution and with the TG composition of original butter oil.

Determination of positional distribution of butyryl groups in milkfat triacylglycerols, triacylglycerol mixtures, and isolated positional isomers of triacylglycerols by gas chromatography and1H nuclear magnetic resonance spectroscopy

Positional isomers (1-butyryl-2X-3Y-rac-glycerol and 2-butyryl-1X-3Y-rac-glycerol;X,Y=long-chain acyls) of saturated triacylglycerols (TAG) with 34 and 40 acyl carbons were shown to separate in two chromatographic peaks on immobilized phenyl(65%) methylsilicone column by gas-liquid chromatography, and on reversed-phase ODS-1 column by high-performance liquid chromatography. The analysis of 500-MHz1H nuclear magnetic resonance (NMR) spectra showed distinct differences between 2-butyryl-1X-3Y-rac-glycerol and 1-butyryl-2X-3Y-rac-glycerol isomers in the resonance signals of methylene and methine protons of glycerol backbone, and carbon-2 methylene of acyl groups, and methyl protons of butyryl group. The1H NMR spectra of three interesterified mixtures of three monoacid TAG containing saturated butyrate and caproate TAG and unsaturated butyrate TAG showed that triplets of methyl protons of butyryl groups atsn-1(3)- andsn-2-positions in saturated and unsaturated TAG had similar chemical shifts and that the chemical shift of caproyl methyl protons was different from those of butyryl methyl protons. The positional distribution of butyryl groups in isolated positional isomers of butyrate TAG, interesterified TAG mixtures, and natural and interesterified butteroil can be determined by integration of these signals.

Fractionation of the triacylglycerols of lipase-modified butter oil

Triacylglycerols (TGs) of lipase-modified butter oil were separated into saturated, monoene, diene and triene fractions on ap-propylbenzene sulfonic acid solid-phase extraction column loaded with silver ions. Fatty acid analysis of the fractions showed that the amounts of saturated TGs (98.4 mol%) and monoene TGs (26.0 mol%) in the saturated and monoene fractions, respectively, were close to the theoretical amounts of TGs in pure fractions. The column method provides a useful alternative to AgNO3-thin-layer chromatography as a means of separating the TGs of butterfat and producing relatively pure TG fractions for further analysis by gas chromatography (GC) or GC-mass spectrometry.

Lipase-catalyzed acidolysis of butterfat with oleic acid: characterization of process and product

The modification of anhydrous butterfat via interesterification reactions with oleic acid catalyzed by a lipase from Mucor circinelloides immobilized by adsorption onto hydrophobic hollow fibers is described. A reasonable degree of incorporation of free (externally added) oleic acid into the triacylglycerols of butterfat has been achieved while short-chain fatty acid residues remained virtually unaffected. Total saturated triacylglycerols decreased by 27%, and triacylglycerols with 32–44 acyl carbons (which contained two or three lauric, myristic, or palmitic acid residues) decreased by 33%. Total monoene and polyene triacylglycerols increased by 21% and 17%, respectively. The triacylglycerols (TAG) of interesterified butterfat had approximately 27% more oleic acid residues and approximately 8% less lauric, 6% less myristic, and 6% less palmitic acid residues than those of the original butterfat; the fraction of low-melting TAG peak increased by 19% whereas that of high-melting TAG decreased by 83%. Although a certain degree of butterfat hydrolysis was observed, enzymatic acidolysis was technically feasible and able to produce a modified butterfat with a stronger nutraceutical character.

Effects of milk fat, unhydrogenated and partially hydrogenated vegetable oils on serum lipoproteins in growing pigs

Abstract 1. 1. Crossbred Yorkshire (Yorkshire × Landrace) pigs were fed butter oil, cream, low erucic acid rapeseed oil, sunflower oil and partially hydrogenated sunflower oil in amounts representing 30% of energy for periods of up to 13 weeks. 2. 2. After 13 wk of feeding serum total cholesterol levels of pigs fed milk fat were significantly higher than of pigs fed vegetable oils. 3. 3. The difference in cholesterol was mainly due to an increase in the density range of 1.063–1.125 g/ml containing pig LDL 2 and some HDL. 4. 4. A shift towards smaller LDL particle size was apparent in pigs fed milk fat. 5. 5. The effects of dietary trans fatty acids did not differ from cis polyunsaturated or monounsaturated fatty acids.