Avances para el análisis de mezclas complejas mediante técnicas cromatográficas multidimensionales

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Analitica y Análisis Instrumental. Fecha de lectura: 08-06-2018Esta tesis tiene embargado el acceso al texto completo hasta el 08-12-201

Use of room temperature ionic liquids for the selective fractionation of bioactive ketoses from aldoses

This work deals with the effective fractionation of bioactive ketoses, i.e. lactulose and tagatose, from their corresponding aldoses, lactose and galactose, in equimolar binary mixtures driven by room temperature ionic liquids, i.e. 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) and 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]), respectively. Under assayed conditions, tagatose was found to be 6-fold more soluble on [BMIM][MeSO4] than galactose; meanwhile lactulose was 3 times more soluble than lactose on [EMIM][DCA]. As an application example in a more complex sample, a lactose isomerization mixture containing in addition lactulose and monosaccharides was enriched in this ketose by using [EMIM][DCA]. Carbohydrates were then successfully recovered from the ionic liquid following an activated charcoal-based treatment. Overall, lactulose content was enriched from a 24% in the initial isomerization reaction mixture to a 62% in the purified sample. These experimental results demonstrated the potential of ionic liquids as green alternative solvents for the selective fractionation of bioactive ketoses from their corresponding aldoses in food and beverage production.Authors thank Ministerio de Ciencia e Innovación (projects AGL2009-11909 and AGL2011-27884), Ministerio de Economía y Competitividad (project CTQ2012-32957) and the European founding from FEDER program for financial support. L. Ruiz-Aceituno is supported by CSIC by a JAE-Pre grant, co-financed by the European Social Fund (ESF). C. Carrero-Carralero thanks Ministerio de Ciencia e Innovación (Spain) for a predoctoral contract.Peer Reviewe

Fractionation of food bioactive oligosaccharides

Bioactive oligosaccharides obtained from either natural or synthetic sources are normally present in highly complex matrices. This heterogeneity is particularly important in the carbohydrate fraction. In this context, the suitable fractionation of bioactive oligosaccharides becomes an important task to broaden their applications, as well as to accomplish their structural and/or functional characterization. This chapter deals with a wide number of techniques at semi- and preparative scale, that is, membrane separation processes, chromatographic techniques, solvent-based methods, and microbiological and enzymatic techniques, whose applications largely depend on the use and the purity required for the fractionated oligosaccharides. The advantages and major drawbacks of the different techniques are also discussed in detail. In addition to well-established techniques, such as ultrafiltration, nanofiltration, size-exclusion, or ion exchange chromatography, this chapter will also describe novel and green techniques which have been recently reported to be useful for the prospective fractionation of oligosaccharides with high recoveries, including pressurized liquid extraction, supercritical fluid and ionic liquids.This work has been financed by Projects AGL2009-11909, AGL2011-27884 and Consolider Ingenio 2010 FUN-C-FOOD CSD2007-00063 from Ministerio de Ciencia e Innovacion, Project S2009/AGR-1464, ANALISYC-II from Comunidad Autonoma of Madrid (Spain) and European funding from FEDER program, project POII10-0178-4685 from Junta de Comunidades de Castilla-La Mancha and European Regional Development Fund (ERDF), and project AGR-7626 from Junta de Andalucía.Peer Reviewe

Selective fractionation of sugar alcohols using ionic liquids

Sugar alcohols, such as xylitol, sorbitol and inositols, are added-value carbohydrates with relevant bioactive and technological properties. These features make their extraction from natural sources of great interest both from the scientific and industrial points of view. However, due to the similarity of the chemical structures of the different carbohydrates and the complexity of the extracted mixtures, the subsequent isolation of these sugar alcohols from other coextracted low molecular weight carbohydrates (LMWC) is still considered a challenging task. In this article, the solubility of linear sugar alcohols and inositols in selected ionic liquids (ILs), i.e., 1-hexyl-3-methylimidazolium chloride ([HMIM][Cl]), 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) and 1,3-dimethylimidazolium dimethylphosphate ([MMIM][MePO]), has been investigated. The experimental results demonstrated widely divergent solubilities (in the 1.7–84.7%, w/w, range) for the several targeted carbohydrates in the different ILs evaluated, with [EMIM][OAc] and [MMIM][MePO] providing the highest solubility values. These ILs gave also the best results when applied to the selective fractionation of sugar alcohols from other LMWC in 1:1 (w/w) binary mixtures (yields in the 60–98% range). These results show ILs as promising non-volatile and environmental friendly solvents for this type of fractionation process and suggest the interest of further investigation in this particular application field.This work has been funded by Fundación Ramón Areces (project CIVP17A2843), by Ministerio de Economía y Competitividad (project CTQ2012-32957) and by Ministerio de Economía, Industria y Competitividad (MINECO) of Spain (project AGL2016-80475-R, AEI/ FEDER, UE). Authors also thank financial support from the Comunidad Autónoma of Madrid and European funding from FEDER program (project S2013/ABI-3028, AVANSECAL).Peer Reviewe

Ionic liquids as an alternative to the separation of bioactive ketoses from aldoses in isomerization mixtures

Resumen del póster presentado a la XIII Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines celebrado en Tenerife del 8 al 11 de octubre de 2013.Lactulose is obtained from lactose by isomerization in basic media using different catalytic systems, and yield ranges from 20 to 80 % dry extract, including variable amounts of lactose and small contents of other sugars. On the other hand, tagatose is a stereoisomer of D-fructose and normally obtained from galactose by an isomerization process. In US is considered a GRAS (Generally Recognized As Safe) product and its use in foods and beverages has been approved in several countries. Both carbohydrates are considered as prebiotics and their purification is of especial interest for the food industry taking into account that these processes represent the 90% of costs of food production. Current commercial processes for purification of carbohydrates are usually based on the use of chromatographic techniques involving ion-exchange resins or activated charcoal. Room temperature ionic liquids (RTILs) are non-molecular ionic solvents and classified as environmentally friendly and provide a safe alternative to the use of traditional organic solvents which produce volatile compounds. In a previous study, we have evaluated the solubilities of aldoses (glucose, galactose, and lactose) and ketoses (fructose, tagatose, and lactulose) in different RTILs at 26 and 45 ºC, detecting significant differences depending on the carbohydrate structure. Therefore, the possibility of using RTILs for the selective separation of binary aldose/ketose mixtures and mixture of synthesis of lactulose from lactose has been evaluated. The best results for the selective separation of the binary mixtures of lactulose - lactose and tagatose - galactose were achieved using [EMIM][DCA] and [BMIM][MeSO4], respectively. The ketose/aldose molar ratios were enriched from 1 to 2.9 in the pair lactulose/lactose and to 2.53 in tagatose/galactose. When these results were applied to the mixture of synthesis, concentration of lactose was notably reduced and the ratio lactulose/lactose raisedfrom 0.5 to1.47. Consequently, these results are the first evidence of the ILs selectivity which can beusefulfor the efficient separation of bioactive ketoses from their corresponding aldoses.Peer Reviewe

Influence of chemical structure on the solubility of low molecular weight carbohydrates in room temperature ionic liquids

The use of room temperature ionic liquids (ILs) as green solvents is an emerging and innovative technology, which is quickly expanding in carbohydrate chemistry. However, information about solubility of low molecular weight carbohydrates (LMWC) in ILs is still scarce. This study provides new solubility data for several LMWC dissolved in methylimidazolium-based ILs. Different solubility values have been obtained for carbohydrates depending on their structure. In general, ketoses are more soluble than their corresponding aldoses, and trisaccharides are more soluble than mono- and disaccharides, although some exceptions have been observed depending on the tested IL. [BMIM][MeSO4] and [HMIM][Cl] acted both as solvent and as catalyst for dehydration of ketoses (fructose and tagatose) into 5-hydroxymethylfurfural at 318 K. These findings pointed out the potential of ILs as an interesting alternative solvent for new applications in applied carbohydrate chemistry.This work has been funded by Ministerio de Ciencia e Innovacion (projects AGL2009-11909 and AGL2011-27884), Ministerio de Economia y Competitividad (project CTQ2012- 32957) and the Comunidad Autonoma of Madrid (Spain) and European funding from FEDER program (project S2009/AGR-1464, ANALISYC-II). L. Ruiz-Aceituno is supported by CSIC by a JAE-Pre grant, cofinanced by the European Social Fund (ESF). C. Carrero-Carralero thanks Ministerio de Ciencia e Innovacion (Spain) for a predoctoral contract.Peer Reviewe

Development of a carbohydrate silylation method in ionic liquids for their gas chromatographic analysis

This paper reports on the feasibility of silylation of low molecular weight carbohydrates dissolved in different ionic liquids (ILs) for their further analysis by gas chromatography (GC). Derivatization reagents (nature and amounts), temperature and time of reaction and stirring conditions were evaluated for different carbohydrates (i.e., glucose, mannose, fructose and lactose) dissolved in 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA]. Evaluation of conformational isomerism of glucose dissolved in [EMIM][DCA] revealed the effect of the time of dissolution in the equilibration of α- and β-furanoses (up to 3% and 6%, respectively, after 70h of incubation) and that 21h sufficed to obtain results similar to those provided by the reference method involving pyridine. Once optimized, the proposed derivatization procedure provided satisfactory yields (i.e., close to 100%) using 100μL of trimethylsilylimidazole (TMSI) at mild conditions (25°C) for a relatively short time (1h) for most of the investigated carbohydrates. Under these experimental conditions, linear responses (i.e., R2 better than 0.974) were obtained in the tested range of 0.25-1mg of the derivatized target compounds. Other reagents, such as N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), were successfully used under ultrasonic conditions for aldose monosaccharides and disaccharides derivatization, while BSTFA was useful for ketose monosaccharides. The possibility of using the proposed method for the derivatization of selected carbohydrates dissolved in different ILs and the efficiency of the method applied to the analysis of carbohydrates present in real samples (fruit juices) have also been investigated. © 2013 Elsevier B.V.This work has been funded by Ministerio de Ciencia e Innovación (project AGL2009-11909), Ministerio de Economía y Competitividad (project CTQ2012-32957) and Comunidad Autónoma of Madrid (Spain) and European funding from FEDER program (project S2009/AGR-1464, ANALISYC-II). L. Ruiz-Aceituno is supported by CSIC by a JAE-Pre grant, co-financed by the European Social Fund (ESF).Peer Reviewe

An untargeted evaluation of the volatile and semi-volatile compounds migrating into food simulants from polypropylene food containers by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

This study reports on the potential of comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC−ToF MS) for the exhaustive untargeted characterization of the volatile and semi-volatile analytes migrating from four commercial polypropylene food containers into four simulants (water, 3% acetic acid, 10% ethanol, and isooctane) according to European Regulation 10/2011. Collected extracts were concentrated and directly subjected to GC×GC−ToF MS analysis without any further treatment to preserve migrants integrity. As expected, the nature and total number of compounds detected in the migrates depended on both the brand (i.e., manufacture and/or sterilization procedure) and the simulant applied. In total, 107 analytes, including some less volatile compounds, were either positively or tentatively identified in the investigated simulants, a number of these compounds being reported for the first time as migrants from this type of material. A database containing chromatographic, mass spectral and partition information concerning these compounds, plus 23 remaining unidentified, is provided.Authors thank MINECO, Spain (projects CTQ2012-32957 and AGL2016-80475-R7, AEI/FEDER-UE). Fundación Ramón Areces and Community of Madrid (Spain) and European FEDER Program, Spain (Project S2013/ABI-3028-AVANSECAL) for financial supportPeer Reviewe

Characterization of (semi-)volatile compounds migrating into food from polypropylene food containers.

Authors thank MINECO (projects CTQ2012-32957 and AGL2016-80475-R7, AEI/FEDER, UE), Fundación Ramón Areces, and Community of Madrid (Spain) and European FEDER program (Project S2013/ABI-3028-AVANSECAL) for financial suppo

Extraction and characterization of low molecular weight bioactive carbohydrates from mung bean (Vigna radiata)

Due to the great interest in obtaining natural bioactive carbohydrates to be used as functional ingredients, a selective microwave assisted extraction (MAE) method was optimized to ensure the exhaustive extraction of inositols and α-galactooligosaccharides (α-GOS) from mung bean. Thereafter, a comprehensive characterization of these compounds was carried out by gas chromatography coupled to mass spectrometry (GC–MS). Apart from free inositols and α-GOS, several glycosyl-methyl-scyllo-inositols and glycosyl-inositols were detected for the first time in this legume. Under optimized MAE conditions (0.5 g dry sample, 2 cycles of 3 min, 50 °C, 10 mL 50:50 ethanol:water, v:v), bioactive carbohydrates yields were similar to those found using solid–liquid extraction (SLE), but with shorter analytical times. Concentrations of bioactive carbohydrates in MAE extracts from samples of different geographical origins ranged between 74.1 and 104.2 mg.g dry sample. MAE was proved a good alternative to SLE to obtain extracts enriched in bioactive carbohydrates.This work has been funded by Fundación Ramón Areces (project CIVP17A2843) and by Ministerio de Economía, Industria y Competitividad (MINECO) of Spain (project AGL2016-80475-R). Authors also thank financial support from the Comunidad Autónoma of Madrid and European funding from FEDER program (project S2013/ ABI-3028, AVANSECAL). C.C.C. thanks MINECO for a predoctoral contract and D.M. thanks CSIC, Fondo Social Europeo and Iniciativa de Empelo Juvenil for a contract.Peer Reviewe