Agnieszka Golon

Unraveling the Chemical Composition of Caramel

Caramel is one of mankinds best known dietary materials obtained from carbohydrates by heating. Much effort has been expended toward the chemical characterization of the components of caramel but impeded by a lack of suitable analytical techniques sufficiently powerful for providing insight into an extraordinarily complex material. This paper reports the characterization of caramel formed by heating from glucose, fructose, and saccharose using a conceptually novel combination of mass spectrometrical techniques. The analytical strategy employed uses high-resolution mass spectrometry (MS) followed by targeted liquid chromatography-tandem MS experiments. Caramel is composed from several thousand compounds formed by a small number of unselective and chemoselective reactions. Caramelization products include oligomers with up to six carbohydrate units formed through unselective glycosidic bond formation, dehydration products of oligomers losing up to a maximum of eight water molecules, hydration products of sugar oligomers, disproportionation products, and colored aromatic products.

What is under the hump? Mass spectrometry based analysis of complex mixtures in processed food – lessons from the characterisation of black tea thearubigins, coffee melanoidines and caramel

In this contribution we review our work on the characterisation of processed food. We review novel methods and analysis strategies developed to account for the composition of extraordinarily complex materials such as black tea thearubigins, coffee melanoidines and thermally treated carbohydrates. Our methods are mainly based on modern mass spectrometry and are introduced and critically discussed. A series of novel previously unpublished data interpretation strategies are presented as well. Finally an evaluation of the insight obtained in the composition of selected processed foods is given discussing potential consequences for assessing beneficial and adverse health effects of processed food.

Characterisation of “caramel-type” thermal decomposition products of selected monosaccharides including fructose, mannose, galactose, arabinose and ribose by advanced electrospray ionization mass spectrometry methods

The chemical analysis of caramel, formed upon heating of carbohydrates, remains a significant challenge due to the complexity of the resulting product mixture. Identification of the products formed upon heating of monosaccharides including fructose, mannose, galactose, arabinose and ribose is essential to understand the composition and properties of carbohydrate-rich processed foods. In this work, we report on the use of combined mass spectrometry techniques, including high performance liquid chromatography and electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)). The composition of the obtained caramel was examined by high resolution mass spectrometry along with van Krevelen and Kendrick analysis. We found that caramel is composed of oligomers with up to six carbohydrate units formed through unselective glycosidic bond formation, their dehydrated products by losing up to eight water molecules, hydrated products and disproportionation products. An accurate mass measurement and subsequent fragment ion studies of all caramel samples (around 40 compounds) can thus be identified. Glycosidic bond and ring cleavages of sugar moieties were the major observable fragmentation pathways during this experiment. The innovative analytical strategies for the complex mixture analysis used provide a comprehensive account of the chemical composition of caramel, one of the most popular dietary materials over the world.

Investigating the thermal decomposition of starch and cellulose in model systems and toasted bread using domino tandem mass spectrometry.

Many dietary products containing polysaccharides, mostly starch and cellulose, are processed by thermal treatment. Similarly to the formation of caramel from mono- and disaccharides, the chemical structure of the carbohydrates is dramatically altered by heat treatment. This contribution investigates the products of thermal decomposition of pure starch and cellulose as model systems followed by an investigation of bread obtained at comparable conditions using a combination of modern mass spectrometry techniques. From both starch and cellulose, dehydrated oligomers of glucose and dehydrated glucose have been predominately observed, with oligomers of more than four glucose moieties dominating. Moreover, disproportionation and oligomers with up to six carbohydrates units are formed through unselective glycosidic bond breakage. MALDI-MS data confirm the presence of the majority of products in toasted bread.

An Investigation of the Complexity of Maillard Reaction Product Profiles from the Thermal Reaction of Amino Acids with Sucrose Using High Resolution Mass Spectrometry

Thermal treatment of food changes its chemical composition drastically with the formation of “so-called” Maillard reaction products, being responsible for the sensory properties of food, along with detrimental and beneficial health effects. In this contribution, we will describe the reactivity of several amino acids, including arginine, lysine, aspartic acid, tyrosine, serine and cysteine, with carbohydrates. The analytical strategy employed involves high and ultra-high resolution mass spectrometry followed by chemometric-type data analysis. The different reactivity of amino acids towards carbohydrates has been observed with cysteine and serine, resulting in complex MS spectra with thousands of detectable reaction products. Several compounds have been tentatively identified, including caramelization reaction products, adducts of amino acids with carbohydrates, their dehydration and hydration products, disproportionation products and aromatic compounds based on molecular formula considerations.

Hill coefficients of dietary polyphenolic enzyme inhibitiors: can beneficial health effects of dietary polyphenols be explained by allosteric enzyme denaturing?

Inspired by a recent article by Prinz, suggesting that Hill coefficients, obtained from four parameter logistic fits to dose–response curves, represent a parameter allowing distinction between a general allosteric denaturing process and real single site enzyme inhibition, Hill coefficients of a number of selected dietary polyphenol enzyme inhibitions were compiled from the available literature. From available literature data, it is apparent that the majority of polyphenol enzyme interactions reported lead to enzyme inhibition via allosteric denaturing rather than single site inhibition as judged by their reported Hill coefficients. The results of these searches are presented and their implications discussed leading to the suggestion of a novel hypothesis for polyphenol biological activity termed the insect swarm hypothesis.

Mass Spectrometric Investigation of the Chemical Composition of Caramel Formed upon Heating of Disaccharides

Disaccharides are a very important group of carbohydrates, being main components of many daily food products. The heating of these biomolecule causes the formation of caramel, an extremely complex material. The dominant fraction of non-volatile compounds, responsible for both color and flavor of food products, has been studied on a few occasions. Herein, the composition of caramels obtained by heating of sucrose, lactose and maltose were studied using combined mass spectrometry techniques. High resolution electrospray mass spectrometry was applied followed by targeted multi-stage LC-tandem mass spectrometry (ESI-MS n ) and MALDI-MS. Novel graphical interpretation strategies such as van Krevelen and Kendrick mass analysis have been applied to study the composition of caramels. Products of caramel include oligomerization, depolymerization, hydration and dehydration products. Oligomers with up to eight carbohydrate units and dehydrated oligomers losing up to eight water molecules have been identified.