Picariello, Gianluca (2013) ADVANCED APPLICATIONS OF MATRIX ASSISTED LASER DESORPTION IONIZATION – TIME OF FLIGHT (MALDI-TOF) MASS SPECTROMETRY IN FOOD LIPIDOMICS. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: ADVANCED APPLICATIONS OF MATRIX ASSISTED LASER DESORPTION IONIZATION – TIME OF FLIGHT (MALDI-TOF) MASS SPECTROMETRY IN FOOD LIPIDOMICS
Creators:
CreatorsEmail
Picariello, Gianlucapicariello@isa.cnr.it
Date: 2 April 2013
Number of Pages: 92
Institution: Università degli Studi di Napoli Federico II
Department: Scienza degli alimenti
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Scienze e tecnologie delle produzioni agro-alimentari
Ciclo di dottorato: 25
Coordinatore del Corso di dottorato:
nomeemail
Barbieri, Giancarlobarbieri@cds.unina.it
Tutor:
nomeemail
Addeo, Francescofrancesco.addeo@unina.it
Date: 2 April 2013
Number of Pages: 92
Uncontrolled Keywords: Lipidomics; MALDI-TOF mass spectrometry; food lipids; triacylglycerols
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/15 - Scienze e tecnologie alimentari
Aree tematiche (7° programma Quadro): SALUTE e TUTELA DEL CONSUMATORE > Sicurezza alimentare, salute degli animali, benessere e salute degli animali e delle piante
Date Deposited: 04 Apr 2013 08:29
Last Modified: 17 Jun 2014 06:04
URI: http://www.fedoa.unina.it/id/eprint/9429

Abstract

The application of matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) to the study of lipids has been long underestimated due to a series of intrinsic limitations associated to the technique, including the interference of matrix ion signals in the low m/z region, the natural tendency of lipids to fragment even under the “soft” ionization conditions of MALDI, the scarce reproducibility of the analysis, the inability in discriminating positional regioisomers or to characterize structural details such as position and geometry of double bonds in unsaturated lipids. In the last decade, because of several technical improvements, both the single-lipid targeted and the lipidome-wide extended investigations, carried out with the exclusive use or the substantial support of MALDI MS, have exponentially increased. MALDI-TOF has become one of the core tools of the recently born “lipidomics” and has proved to boast a series of unarguable advantages in the analysis of complex lipid mixtures, such as i) minimal sample handling; ii) no derivatization needed; iii) short analysis time required (1-2 min); iv) very high specificity, resolution and reliability; v) high sensitivity and dynamic range; vi) relative straightforward assignment of signals in the mass spectra; vii) possibility of performing analysis in mixture, without any previous chromatographic step. We have explored the possibility of extending the application of MALDI-TOF MS to food-related analytical concerns, with progressively increasing challenges. Several quick strategies of sample pre-treatment have been developed to significantly enhance the capabilities and the analytical applicability of MALDI-TOF in food lipidomics, especially aimed to the analysis of triacylglycerols (TAG) in edible oils and fats. For instance, bromine addition to double bonds isolates the contribution of saturated TAGs from animal fats in the mass spectra. Similarly, the catalytic hydrogenation of TAGs allows to profile the pattern of the TAG families in complex mixtures (i.e. milk fat, fish oils) and to detect very low-abundance TAG classes. The silica gel pre-fractionation prevents ion suppression, allowing to profile polar separately from non-polar fractions. This analysis has allowed to identify several categories of neo-formed components in thermo-oxidized edible vegetable oils (sunflower and virgin olive oil) which underwent deep-frying conditions, as well as to discover TAG-derived species non detected before. Silica gel pre-partition has been preliminarily utilized also to investigate lipolysis in fermented meat products such as salami. Several successful tests were also performed to isolate and analyze by MALDI-TOF MS non-TAG lipids. To this purpose, phospholipids have been selectively enriched from complex food lipid mixtures, using hydroxyapatite as an innovative support for solid-phase extraction. A very promising strategy of sample deposition, that consists of the co-crystallization of lipids and matrix over a thin nitrocellulose (NC) substrate film, minimizes or completely abolishes TAG fragmentation. In addition, NC MALDI-TOF MS suppresses matrix ionization and improves the analytical repeatability. These aspects enable MALDI MS to the reliable quantitative evaluation of TAG and TAG-related species which derive from oxidative and hydrolytic scission, provided that suitable internal standards are selected. Although the strategies outlined in this Thesis are virtually of general applicability in lipidomics, they have been specifically tailored for addressing analytical issue related to the study of food lipids. The rationale and targeted application of the MALDI MS-based strategies exhibits wide applicative capabilities to support the food science and technology under several aspects which include food quality, traceability, authenticity, nutritional properties, legal purpose assessment and monitoring of the modification induced by technological treatments on foodstuff.

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