1,721,101 research outputs found
One-step characterization of triacylglycerols from animal fat by MALDI-TOF MS.
No full textComparative characterization of milk fat, lard, and beef tallow triacylglycerols (TAG) has been achieved by using matrix-assisted laser desorption/ionization–time-of-flight (MALDI-TOF) mass spectrometry (MS). The samples formed characteristic patterns, with major TAG signals differing in quantity and intensity according to the fat. In milk fat, the significant contribution of short-chain fatty acids (C4–C10) extends the TAG number to the C20–C60 range. In lard and beef tallow, C12–C18 fatty acids restrict the range to C48–C54, also typical of vegetable oils. Fats originating from ruminants contain odd TAG missing in lard. Signature TAG were identified for each animal fat. C20–C46 specifically fingerprint milk fat; 52:5, 54:5 and 54:6 TAG mark lard; and 55:0, 55:1, 55:2 and 54:0 TAG typify beef tallow. Fats were also analyzed after hydrogenation or bromination; hydrogenation helped to fingerprint the low-abundant long-chain TAG and to distinguish short-chain native TAG from collision-induced fragments; bromination allowed clear separation of saturated and unsaturated TAG. Differences in the fatty acid composition amongst homologous isobaric TAG of different structures were identified by post-source decay analysis of hydrogenated precursors. MALDI-TOF has provenadvantageous for simultaneously detecting TAG at various unsaturation degrees within different TAG classes (Cn). The data provide insight into animal fat differentiation on a molecular basis, increasing the analytical description to a new level, proving the so far underestimated capacity of MALDI-TOF MS in this field
One-step characterization of triacylglycerols from animal fat by MALDI-TOF MS.
No full textComparative characterization of milk fat, lard, and beef tallow triacylglycerols (TAG) has been achieved by using matrix-assisted laser desorption/ionization–time-of-flight (MALDI-TOF) mass spectrometry (MS). The samples formed characteristic patterns, with major TAG signals differing in quantity and intensity according to the fat. In milk fat, the significant contribution of short-chain fatty acids (C4–C10) extends the TAG number to the C20–C60 range. In lard and beef tallow, C12–C18 fatty acids restrict the range to C48–C54, also typical of vegetable oils. Fats originating from ruminants contain odd TAG missing in lard. Signature TAG were identified for each animal fat. C20–C46 specifically fingerprint milk fat; 52:5, 54:5 and 54:6 TAG mark lard; and 55:0, 55:1, 55:2 and 54:0 TAG typify beef tallow. Fats were also analyzed after hydrogenation or bromination; hydrogenation helped to fingerprint the low-abundant long-chain TAG and to distinguish short-chain native TAG from collision-induced fragments; bromination allowed clear separation of saturated and unsaturated TAG. Differences in the fatty acid composition amongst homologous isobaric TAG of different structures were identified by post-source decay analysis of hydrogenated precursors. MALDI-TOF has provenadvantageous for simultaneously detecting TAG at various unsaturation degrees within different TAG classes (Cn). The data provide insight into animal fat differentiation on a molecular basis, increasing the analytical description to a new level, proving the so far underestimated capacity of MALDI-TOF MS in this field
Use of brush border membrane vesicles to simulate the human intestinal digestion
No full textThe intestine presides over a series of vital functions in the human body, among which the digestion/absorption of nutrients. Despite their major digestion role, the impact of the enzymes of the luminal intestinal surface on food components has been considered in relatively few experiments of simulated gastrointestinal digestion. In contrast, the identification of proteolitically stable peptides which survived digestion in multiphasal models that also included a step with small intestinal brush border membrane (BBM) peptidases has provided physiologically consistent results. Herein, we critically review the use of BBM enzymes to simulate the intestinal digestion of dietary polypeptides. Addressing the controversial issue of the in vitro-in vivo correspondence of the digestion models, the review emphasizes the need to establish consensus protocols to simulate the intestinal step, for instance using the BBM hydrolases at least in a selected number of cases. The factors that have limited the development of relevant models of intestinal degradationare discussed together with hints to possible alternatives, forthcoming approaches and future perspectives to reproduce the physiopathology of the human small intestine. (C) 2015 Elsevier Ltd. All rights reserved
Accurate determination of total biophenols in unfractionated extra-virgin olive oil with the fast blue BB assay
Full text linkThe phenolic compounds of extra-virgin olive oil (EVOO) are key contributors of nutritional and sensory quality as well as chemical stability. The reference method for their determination is the HPLC-UV, which is cost-/time-expensive. In this work, total phenolic compounds were evaluated in unfractionated EVOO adapting the Fast Blue BB (FBBB) assay, which involves the spectrophotometric (absorbance at 420 nm) determination of azo derivatives resulting from the coupling of phenolic compounds with FBBB diazonium salt in alkali pH. When tested on 26 EVOO samples, the FBBB assay and HPLC-determinations were strikingly correlated (R2 = 0.9653), differently from FBBB and Folin-Ciocalteu assays, which showed poor correlation. The assay is simple, repeatable, robust, rapid and cheap, and results might be evaluated on a printed colorimetric scale. This protocol of the FBBB assay could be routinely used to categorize EVOO according to the health claim allowed by EFSA concerning the content of phenolic compounds
Hydroxyapatite affinity chromatography for the highly selective enrichment of mono- and multi-phosphorylated peptides in phosphoproteome analysis
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Maldi-tof mass spectrometry profiling of polar and nonpolar fractions in heated vegetable oils
No full textTriacylglycerol oxidation of thermally stressed (6 h at 180 °C, simulating deep-frying conditions) edible vegetable oil (sunflower and olive) was studied using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Chromatographic separation of the nonpolar and polar components from the heated oil performed on silica gel prior to MS analysis significantly enhanced the detection of oxidized components. The spectra contained signals that were assigned to triacylglycerols (TAG), diacylglycerols (DAG), triacylglycerol oxidative dimers, oxidized TAG, and TAG fragments arising from the homolytic β-scission of linoleyl, peroxy, and alkoxy radicals. Enrichment of the polar compounds prevented mass spectrometric ion suppression, thus allowing the detection of minor species originating from thermal oxidation. In addition, this allowed the monitoring of polar compounds in vegetable oils undergoing mild thermal treatment. As such, chromatographic separation coupled with MALDI-TOF MS analysis provided a rapid, sensitive, and specific tool to assess the thermal oxidation of vegetable oils
Mass spectrometric analysis of in vitro nuclear aggregates of polyamines.
No full textRATIONALE: In the nuclei of eukaryotic cells, polyamines and phosphate ions self-assemble via ionic interactions and hydrogen bonding, generating three families of supramolecular compounds that have been named large (l-), medium (m-) and small (s-) nuclear aggregates of polyamines (NAPs). In a simulated nuclear environment, polyamines and phosphate ions generate the in vitro NAPs (ivNAPs) that share strict structural and functional analogies with their cellular cognates. Mass spectrometric data are expected to provide important structural details of NAPs/ivNAPs.
METHODS: We used both electrospray ionization (ESI) and nitrocellulose (NC) matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to support a variety of analytical techniques previously addressed to structurally characterize NAPs/ivNAPs.
RESULTS: The dominant m/z values of s-ivNAP (m/z 735, 749, 761) are compatible with a defined set of cyclic or linear aggregates. On the basis of the experimental molecular mass (a cluster centred at m/z 2980), the m-ivNAP corresponds to the supramolecular assembly of four modules of s-ivNAPs. No informative mass spectra were obtained for the l-ivNAP.
CONCLUSIONS: MS data support the models of NAPs that have been inferred by using an array of analytical techniques. NC MALDI-MS contributed much more effectively than ESI-MS to the structural characterization of ivNAPs
Mass spectrometry in the study of anthocyanins and their derivatives: differentiation of Vitis vinifera and hybrid grapes by liquid chromatography/electrospray ionization mass spectrometry and tandem mass spectrometry.
No full textA mass spectrometric-based procedure for anthocyanin profiling was set up to distinguish authentic Vitis vinifera from hybrid red grapevine cultivars. 3-O-Monoglucoside and the related acetyl-, p-coumaryland caffeoyl-monoglucoside anthocyanins occurred only in Vitis vinifera, whereas 3,5-O-diglucoside and the substituted acetyl-, p-coumaryl-, feruloyl- and caffeoyl-diglucoside anthocyanins were the additional pigments in hybrid grapevines. The procedure was applied expressly to identify red grape cultivars based on the anthocyanin chemo-type determination. In particular, a red grape cultivar, having 3,5-O-diglucoside anthocyanins and a novel class of anthocyanin monoglucosides, such as cyanidin-3-O-, cyanidin-3-O-(6-O-acetyl)- and cyanidin-3-O-(6-O-p-coumaryl)pentoside, was classified as hybrid. A second vine cultivar, characterized exclusively by 3-O-monoglucoside anthocyanins, was included among the Vitis vinifera species. Anthocyanin profiling by mass spectrometry could represent the core of a chemotaxonomic procedure for distinguishing American and European grapevines based on the identification of postsynthetic anthocyanidin modification
Determinazione e caratterizzazione di proteine tossiche con attività emagglutinante (fitoemagglutinine) in prodotti industriali derivati da fagioli(Phaseolus vulgaris).
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