Nuevos métodos de extracción y fraccionamiento de carbohidratos bioactivos

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 27-11-2015The extraction of bioactive carbohydrates, such as inositols and prebiotics, from natural sources is of great interest for their use as food ingredients due to the benefits they represent to consumers' health. These compounds are involved in several biological processes related with metabolic disorders or inducing changes in gut microbiota. The potential use of these bioactive ingredients from the food and / or pharmaceutical industry makes that the search for new extraction alternatives, more effective and advantageous than the available ones, gains an increasing importance. Therefore, the main objective of this PhD dissertation is the development of new methods for the extraction and selective fractionation of bioactive carbohydrates (inositol and prebiotics). To achieve this goal, two main research lines have been addressed: (i) the evaluation of the use of new solvents (ionic liquids, ILs) for the selective fractionation of carbohydrates based on their chemical structure, and (ii) the development of new methods of extraction and enrichment of bioactive carbohydrates from natural matrices. First of all, it was necessary to develop a derivatization method that allows the analysis of low molecular weight carbohydrates (LMWC) dissolved in ILs by gas chromatography (GC). The optimized and validated method proved to be effective for this purpose, being this the first time that carbohydrates dissolved in ILs are analyzed by this technique. Subsequently, and due to the scarce data published so far in the literature on the solubility of LMWC in ILs, solubility studies of different monosaccharides, polyols, disaccharides and trisaccharides in methyl-imidazolium based-ILs were carried out, and these values were related to their chemical structure. ILs were found to be promising solvents for the selective fractionation of aldoses and bioactive ketoses, such as lactose and lactulose, as well as several polyols and other LMWC. Prior to the development of extraction methods, significant advances in qualitative and quantitative determination of the LMWC (particularly inositol and prebiotics) present in different food matrices (pine nuts, vegetables, legumes) were carried out by GC-MS after derivatization to their corresponding trimethylsylil oximes (TMSO). Different carbohydrates were identified for the first time in these matrices. In this thesis, pressurized liquid extraction (PLE) and microwave assisted extraction (MAE) were selected to evaluate their efficiency in the extraction of bioactive carbohydrates, as well as their respective advantages and disadvantages. The developed PLE and MAE methods allowed to obtain greater yields of inositols than those achieved by the conventional solid-liquid extraction method, using shorter extraction times and with a lower solvent consumption. Moreover, the developed methods allowed, for the first time, the simultaneous extraction of inositol and inulin from food industry by-products. Finally, a biotechnological process based on the use of Saccharomyces cerevisiae which allowed the removal of coexisting sugars in the extracts that might interfere with the bioactivity of the carbohydrates of interest has been optimized. The results described in this thesis represent a remarkable contribution to the study of carbohydrates, as well as to the development of new ingredients and bioactive supplements, which is a subject of great interest and scientific and economic impac

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

Nuevos métodos de extracción y fraccionamiento de carbohidratos bioactivos

Los resultados descritos en esta Tesis suponen una contribución destacable en el estudio de carbohidratos, así como en la obtención de nuevos ingredientes bioactivos, tema éste de gran actualidad y repercusión tanto científica como económica.La obtención de carbohidratos bioactivos, como son los inositoles y prebióticos, presenta un gran interés para su uso como ingredientes alimentarios, por los beneficios que éstos suponen para la salud de los consumidores. Dichos compuestos están implicados en diversos procesos biológicos relacionados, en especial, con alteraciones metabólicas o con la inducción de cambios en la microbiota intestinal. El potencial empleo de estos ingredientes bioactivos por parte de la industria alimentaria y/o farmacéutica hace que la búsqueda de nuevas vías para su obtención, que sean eficaces y ventajosas frente a las ahora disponibles, cobre cada vez mayor importancia.En línea con esta observación, el objetivo principal de esta tesis doctoral es el desarrollo de nuevos métodos para la extracción y el fraccionamiento selectivo de carbohidratos bioactivos (inositoles y prebióticos). Para alcanzar este objetivo, se han abordado dos líneas principales de investigación: (i) la evaluación del empleo de nuevos disolventes (líquidos iónicos, ILs) para el fraccionamiento selectivo de carbohidratos en función de su estructura química, y (ii) el desarrollo de nuevos métodos de extracción y enriquecimiento de carbohidratos bioactivos a partir de matrices naturales. Previo a la evaluación del empleo de ILs para el fraccionamiento selectivo de carbohidratos, fue necesario desarrollar un método de derivatización que permitiera el análisis de carbohidratos de bajo peso molecular (LMWC) disueltos en estos disolventes por cromatografía de gases (GC). El método optimizado y validado resultó ser eficaz para este fin, siendo la primera vez que carbohidratos disueltos en ILs eran analizados por esta técnica. Posteriormente, y dada la escasez de datos bibliográficos sobre la solubilidad de LMWC en ILs, se llevaron a cabo estudios de solubilidad de distintos monosacáridos, polialcoholes, disacáridos y trisacáridos en ILs basados en metil-imidazolio pudiéndose relacionar dichos valores con su estructura química. Los ILs resultaron ser disolventes prometedores para el fraccionamiento selectivo de aldosas y cetosas bioactivas, tales como lactosa y lactulosa, así como de distintos polialcoholes y otros LMWC.Previo al desarrollo de métodos de extracción, se llevaron a cabo avances en la determinación cuali- y cuantitativa de los LMWC (en particular de inositoles y prebióticos) presentes en distintas matrices alimentarias (piñones, vegetales, legumbres) por GC-MS determinándose compuestos no identificados hasta el momento. En esta Tesis, se seleccionaron la extracción con líquidos presurizados (PLE) y la extracción asistida por microondas (MAE) con el fin de evaluar su potencial en este campo de aplicación, así como sus correspondientes ventajas e inconvenientes. Los métodos de PLE y MAE desarrollados permitieron obtener rendimientos en inositoles superiores a los conseguidos por el procedimiento convencional de extracción sólido-líquido, pero con tiempos de extracción más cortos y con un menor consumo de disolvente. Además, los métodos desarrollados consiguieron por primera vez la extracción conjunta de inositoles e inulina a partir de subproductos de la industria alimentaria. Por último, se ha profundizado en el fraccionamiento de carbohidratos usando un procedimiento biotecnológico basado en el uso de Saccharomyces cerevisiae que permitió la eliminación de azúcares coexistentes en los extractos que podrían interferir con la bioactividad de los carbohidratos de interés.Peer reviewe

Quantification of furosine and hydroxymethylfurfural in Spanish powdered infant formulas (IFs)

Póster presentado a: "The Food Factor I Barcelona Conference", 2-4 November 2016, Barcelona (Spain).The manufacture of infant formulas (IFs) includes different steps such as blending of components, homogenisation, pasteurization, spray-drying and storage that have a great influence in their final quality. In processes involving heat, reactions and/or interactions between constituents can give rise to a loss of nutritive value being this very important because IFs sometimes are the only source of infant nutrition during the first months of life. Maillard reaction (MR) is one of the main reactions causing deterioration of proteins during processing or storage of foods. Because IFs may contain high level of carbohydrates and proteins, MR plays an important role during elaboration from the point of view of losses of nutritive value. MR is a very complex reaction that covers a whole range of transformations that produces a large number of the so-called MR products. Different compounds have been selected as indicators of different stages of MR being the furosine (2-furoylmethyl lysine) one the most used, in processed foods as an index of early stages of MR. Besides, hydroxymethylfurfural (HMF) has been used as indicator of advanced stages as a result of excessive heating or storage.Funding from the Spanish MINECO (AGL2014-53445-R), ALIBIRD-CM S-2013/ABI-272 and Spanish Danone Institute. Carlos Sabater thanks his FPU Predoc contract from Spanish MECD (FPU14/03619).Peer Reviewe

Use of ionic liquids in analytical sample preparation of organic compounds from food and environmental samples

This review highlights relevant advances in the use of ionic liquids (ILs) for analytical extraction and purification of organic compounds from food and environmental matrices.Following a technique-based structure, we discuss advantages and shortcomings of ILs compared to conventional volatile organic solvents. We focus on the use of ILs in modern miniaturized extraction techniques, highlighting recent trends. However, when relevant, we also consider more classical approaches to sample preparation.We discuss remaining limitations, gaps detected and possible future developments in this research area.Finally, we illustrate the feasibility of the several analytical procedures for the analysis of relevant organic and biomolecules in foodstuffs and environmental samples of different natures on the basis of representative studies of applications.Authors thank Professor Udo Brinkman for his editing and useful contributions to this paper. This work was funded by projects AGL2009-11909 (Ministerio de Ciencia e Innovacion) and CTQ2012-32957 (Ministerio de Economía y Competitividad). L. R.-A. is supported by CSIC, via a JAE-Pre grant co-financed by the ESF.Peer Reviewe

Inositoles en alimentos: estructura, propiedades y funcionalidad

[ES] En este trabajo se detallan las características y propiedades de los inositoles, discutiendo también su presencia en alimentos, así como los métodos de extracción y análisis más habituales para su determinación en estas matrices. Los inositoles son polialcoholes cíclicos de 6 átomos de carbono con un grupo hidroxilo en cada uno de ellos. Estos compuestos se encuentran principalmente en los alimentos de origen vegetal (frutas, legumbres, semillas, etc.), aunque también se han detectado en cantidades más bajas en alimentos de origen animal. Los métodos de análisis más empleados para la determinación de inositoles son los basados en la cromatografía de gases (GC) previa derivatización como trimetilsilil éteres. A los inositoles se les atribuyen diversas propiedades funcionales, entre las que destaca su eficacia contra la insulinorresistencia siendo de especial interés en el tratamiento de pacientes con diabetes mellitus tipo 2 y mujeres que padecen síndrome de ovario poliquístico.[EN] This paper details the characteristics and properties of inositols, discussing also its presence in foods as well as the more common methods of extraction and analysis for its determination on these matrixes. Inositols are cyclic polyols composed of 6 carbon atoms with a hydroxyl group in each of them. These compounds are primarily found in plant based foods (fruits, vegetables, seeds, etc.), although they have also been detected in foods of animal origin at lower levels. The most commonly used analytical methods for the determination of inositols are those based on gas chromatography (GC) previous derivatization as trimethylsilyl derivatives. Several functional properties have been attributed to the inositols, highlighting its effectiveness against insulin resistance being of special interest in treating patients with type 2 diabetes mellitus and women with polycystic ovary syndrome.Este trabajo ha sido financiado por los proyectos AGL2009-11909 (Ministerio de Ciencia e Innovación) y ANALISYC-II S2010/AGR-1464 (Comunidad de Madrid). L. Ruiz-Aceituno agradece su beca JAE-PreDoc concedida por el Consejo Superior de Investigaciones Científicas (CSIC) y cofinanciado por el FSF.Peer reviewe

Low molecular weight carbohydrates in pine nuts from Pinus pinea L.

Low molecular weight carbohydrates in pine nuts from Pinus pinea L. (n = 7) have been studied by gas chromatography-mass spectrometry as their trimethylsilyl oximes. Besides previously reported components, such as glucose, fructose, sucrose, and raffinose, several soluble carbohydrates have been identified for the first time in this product, including saccharides (galactose, maltose, and planteose) and cyclitols (pinitol, galactinol, galactopinitol A1, fagopyritol B1, and other glycosyl-inositols). Most abundant cyclitols were chiro-inositol, fagopyritol B1, and pinitol, with concentrations ranging from 126.7 to 222.1 mg (100 g) -1, 94.2 to 177.1 mg (100 g) -1, and 51.2 to 282.8 mg (100 g) -1, respectively.Peer Reviewe

Purification of lactulose derived-galactooligosaccharides from enzymatic reaction mixtures

This study compares two different procedures for purification of lactulose-derived galactooligosaccharides (GOS) using fresh Saccharomyces cerevisiae yeast or activated charcoal with water or ethanol/water solutions for selective removal of monosaccharides. Yeast fermentation allowed the complete removal of monosaccharides without any losses of di- and oligosaccharides; however besides ethanol, glycerol and higher alcohols difficult to remove are also produced. The presence of higher alcohols affects the sensory quality of the lactulose-derived GOS and may limit its use in certain food applications. Fractionation of these oligosaccharides using activated charcoal was compared with that of lactose-derived GOS the latter being the most strongly adsorbed. When water was utilised as solvent, all monosaccharides were removed, as well as about 20% of unreacted disaccharides. Removal of tri-, tetra- and pentasaccharides was not observed. Using water/ethanol mixtures, desorption of oligosaccharides increased with ethanol content, allowing the selective recovery of different sugar fractions.This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (AGL2017-84614-C2-1-R), the Autonomous Community of Madrid (project ALIBIRD-CM S-2013/ABI-2728) and Spanish Danone Institute. L. C. Julio-González thanks the governorship of Bolivar–Colombia for the scholarship granted in the project “Bolívar gana con Ciencia”. “L.R-A. thanks the Spanish Research Council (CSIC) and the Spanish Ministry of Economy, Industry and Competitiveness for a Juan de la Cierva contract”. WPeer reviewe

Determination of free inositols and other low molecular weight carbohydrates in vegetables

Different low molecular weight carbohydrates including saccharides, polyalcohols, sugar acids, and glycosides have been identified and quantified in different edible vegetables from Asteraceae, Amarantaceae, Amarylidaceae, Brassicaceae, Dioscoreaceae, and Solanaceae families by gas chromatography-mass spectrometry. Apart from glucose, fructose, and sucrose, other saccharides such as sedoheptulose in chicory, spinach, cabbage, purple yam, eggplant, radish, and oak leaf lettuce, rutinose in eggplant skin, and a glycosyl-inositol in spinach have been identified. chiro-Inositol was found in all vegetables of the Asteraceae family (3.1-32.6 mg 100 g-1), whereas scyllo-inositol was detected in those of purple yam, eggplant, artichoke, chicory, escarole, and endive (traces-23.2 mg 100 g-1). α-Galactosides, kestose, glucaric acid, and glycosyl-glycerols were also identified and quantified in some of the analyzed vegetables. Considering the bioactivity of most of these compounds, mainly chicory leaves, artichokes, lettuces, and purple yam could constitute beneficial sources for human health. © 2011 American Chemical Society.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