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Unraveling the Chemical Composition of Caramel

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... We aim to unravel the complexity of caramel, formed when these carbohydrates are heated. The most dietary relevant disaccharides are sucrose (or saccharose) [22,23], lactose a reducing disaccharide abundant in milk and dairy products and maltose, present in malt and beer. While heating of sucrose produces classical caramel used in traditional cooking, baking and as food additive for coloring of beverages or baking goods, heating of lactose occurs frequently in traditional baking recipes with added dairy products or the production of the Hispanic "dulce de leche" and maltose is heated prior to traditional beer brewing. ...
... For galactose, a dehydration process leading to a galactose based ion at m/z 161.1 is favoured (see later for detailed discussion). Epimerization was shown to be not observed for monomeric hexoses previously [23], as it has been reported in quinic acid and chlorogenic acid chemistry in food processing chemistry at identical temperatures [32,33]. ...
... The elimination of water molecule from glucose at C1-C4 positions forms an enol which tautomerises to its carbonyl form, as expected according to NMR and IR data analysis (Fig. 8) Targeted tandem LC-MS measurements producing EICs of the ion at m/z 323.1 revealed 10 chromatographically resolved peaks for heated sucrose 1, six for heated maltose 2 and 10 for heated lactose 3 (see supplementary information). For sucrose one chromatographic peak was showing retention time and MS 2 spectra identical to difructosedianhydride 11, two compounds showed data resembling dehydration products 9, 10 and 12 of heated maltose 2, as well previously observed for heated glucose [23]. The remaining seven signals showed tandem MS not previously observed and are tentatively assigned as dehydration products of sucrose loosing water at the fructose or glucose moiety. ...
... The examination of the spectra aimed initially at the identification of typical caramelization reactions products [20,21]. From the experimental mass lists, molecular formula lists were generated and compared to those obtained for typical caramelization reactions in the absence of amino acids. ...
... The comparison of peaks with identical accurate mass values and, therefore, molecular formulae, if compared to previous studies on caramelization processes, allowed the tentative identification of around 70 caramelization products, including oligomers of hexoses, with up to a maximum of six monomeric units, both dehydration products of monomeric hexoses and oligomeric hexoses showing successive a loss of up to seven water molecules, depending on the number of monomers. Hydration products with up to two water molecules added to an oligomeric carbohydrate were detected [19,20]. Fragmentation products after the redox disproportionation reaction were found and also aromatic compounds after excessive dehydration. ...
... The distribution shows that one-nitrogen-containing molecules are placed next to the carbohydrate-type molecules on the diagonal line towards point zero, suggesting the dehydration products. From these data, it must be concluded that oligopeptide-like structures are formed with three and more nitrogen atoms, with oligomerization playing an important role in the Maillard reaction, as shown earlier for caramelization [19][20][21] Compounds with two nitrogen atoms are mainly around 0.5 and 1.5 for the O/C and H/C ratio, respectively, and go toward the more aromatic region. On the other hand, compounds with three nitrogen atoms are placed mainly around the point of 0.3 for O/C and 1.2 for H/C, forming one circle. ...
Article
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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.
... Caramel colors are one of the most widely used food additives in the world, which are consumed over 500000 tons per year. [1] There are four types of caramel colors classified by the manufacturing processes, namely the plain caramel (type I), the caustic sulfite caramel (type II), the ammonia caramel (type III), and the sulfite-ammonia caramel (type IV). [2,3] The applications of types III and IV caramels have been limited by the food security administrations such as FDA and SFDA, because the cancerogenic substance 4-methylimidazole could be yielded along with the manufacture of these caramels. ...
... Chemically, this class of caramels is known as a complex mixture consisting of polymeric sugars and flavor components. [1,7] Several volatile components from heated anhydrous sugars have been identified such as furans, furanones, and pyranones. [1,8,9] The sugar-water system in caramel manufacture could give a preferable flavor but the flavor components of this system are not known clearly. ...
... [1,7] Several volatile components from heated anhydrous sugars have been identified such as furans, furanones, and pyranones. [1,8,9] The sugar-water system in caramel manufacture could give a preferable flavor but the flavor components of this system are not known clearly. [9] Moreover, it has been reported that the caramel flavors such as 5-hydroxymethylfurfural (5-HMF) exhibited antioxidant and antibacterial activities. ...
Article
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In this study, the type I caramel reactions of the glucose-water system were carried out. The glucose caramel products (GCPs) at different reaction stages were collected and the reaction rate, UV absorption, flavor compound, and the antioxidant and antibacterial activities were determined. The result showed that the glucose reaction rate of the GCP yielded at 180°C and 4 min arrived at the stable range of around 80.0%. For UV absorptions of GCPs at 305 nm increased approximately in the exponential order. Moreover, the GCP yielded at 180°C and 4 min was revealed to have the highest concentration of main flavor compounds and potent antioxidant and antibacterial activities.
... The best-known examples are the thermal conversion of glucose and sucrose to caramel and the Maillard reaction between saccharides and amino acids at elevated temperatures, forming materials referred to as melanoidins. The colored substances are mainly aromatic compounds [5]. Three types of pyrodextrins, namely white dextrin, British gum, and yellow dextrin, are prepared under different conditions, and they have different colors such as white and brown [6]. ...
... The D% and R% values were evaluated to select the optimal resin. The effect of different solution concentrations of 5,10,15,20,25,30,35,40, and 45 mg/mL was investigated with a decolorization time of 4.0 h, a pH of 7.0, and a temperature of 30 • C. ...
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In this study, an efficient method for the purification of resistant dextrin (RD) using membrane filtration and anion exchange resin decolorization was developed, then the purified RD was characterized. In the membrane filtration stage, suspended solids in RD were completely removed, and the resulting product had a negligible turbidity of 2.70 ± 0.18 NTU. Furthermore, approximately half of the pigments were removed. Static decolorization experiments revealed that the D285 anion exchange resin exhibited the best decolorization ratio (D%), 84.5 ± 2.03%, and recovery ratio (R%), 82.8 ± 1.41%, among all the tested resins. Under optimal dynamic decolorization conditions, the D% and R% of RD were 86.26 ± 0.63% and 85.23 ± 0.42%, respectively. The decolorization efficiency of the D285 resin was superior to those of activated carbon and H2O2. Moreover, the chemical characteristics and molecular weight of RD did not change significantly after purification. The nuclear magnetic resonance spectroscopy of RD showed the formation of new glycosidic linkages that are resistant to digestive enzymes. The superior water solubility (99.14%), thermal stability (up to 200 °C), and rheological properties of RD make it possible to be widely used in food industry.
... Процессы карамелизации углеводов протекают как в растворах, так и в процессах «сухой» термодеструкции, каталитически ускоряясь кислотами, щелочами [2], солями аминокислот [3]. Важность изучения закономерностей данных процессов и структуры формирующихся продуктов неоднократно подчеркивалась вследствие их существенной зависимости от внешних и внутренних факторов; недавними исследованиями [4] было показано, что основными процессами, приводящими к образованию ка-рамелей, являются гликозирование и раскрытие углеводных циклов. Механизм образования О-гликозидов как результата поликонденсации низкомолекулярных углеводов известен давно [5], к настоящему времени в химии гликозидов разработан ряд синтетических методов [6] их получения, но структура формирующихся продуктов авторами цитируемых работ [1][2][3]5] не обсуждается. ...
... В первом случае (I) происходит щелочной сольволиз мальтозы с одновременным образованием 1,2-ангидроциклов (1), которые впоследствии могут трансформироваться в 1,6ангидроструктуры (2) [11], при этом, по мнению авторов [4], описанные превращения могут протекать в сформированных предварительно олигогликозидных цепях. Данный вариант развития процессов, вероятно, более характерен для «сухой» карамелизации. ...
... The EPR free radical signal in roasted coffee beans is associated with colored products, known generally as melanoidins, which are formed as a result of the Maillard and caramelization reactions. The Maillard reaction involves condensation between amino acids or proteins and reducing sugars or carbohydrates (Nursten, 2005), whereas the caramelization reaction is just based on reactions of sugars or carbohydrates (Golon and Kuhnert, 2012). The free radical intensity trace in Figure 67.2 shows an initial rapid burst of free radical activity at about 200°C. ...
... Thus the melanoidins in dark roasted coffee may be associated more with caramelization than Maillard reaction products, though we are unaware of any specific chemical data to indicate that this is indeed the case. Sugar degradation in the caramelization reaction is also extremely complex, and a large number of compounds are formed as a result of a small number of unselective and chemoselective reactions (Golon and Kuhnert, 2012). 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. ...
Chapter
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This chapter briefly reviews the roles played by free radical processes during the roasting and storage of coffee beans and solid coffee products. During roasting, free radical production occurs in distinct phases, possibly related to the Maillard and caramelization reactions. At the same time there is also generation of large quantities of molecules with antioxidant properties, thus demonstrating that antioxidant production does not necessarily equate to free radical scavenging, insofar as it is measured by current assays. Furthermore, with respect to chemical components that are associated with desirable sensory properties of coffee, free radical processes may have both beneficial and detrimental effects.
... Reactions of sugars are not only limited to the decomposition reactions but inter-and intramolecular glycoside bond formations are also observed. Oligomers with up to six carbohydrate units may form during caramelization of glucose, fructose, and sucrose via glycosidic bonding (Golon and Kuhnert, 2012;Golon and Kuhnert, 2013). These oligomers are also found in their dehydrated (up to eight H 2 O loss) and hydrated forms. ...
Chapter
Caramelization is a nonenzymatic browning reaction of sugars providing a caramel-like flavor during high temperature treatments of foods. A wide range of consecutive and parallel reactions may occur during heating of sugars, and the quantitative distribution of the intermediates and products depend largely on pH, water activity, redox potential, and food structure. Caramel flavor and color are the characteristic outcomes of the thermal processing from the viewpoint of food quality, and it can be controlled to achieve desirable properties. However, due to the formation of possible toxic compounds, the process should be controlled in a way to minimize harm from the point of view of food safety. This is still a challenge for food scientists because of the complexity of foods as reactive dynamic systems where complicated reactions take place, especially at high temperatures.
... The degradation of sucrose was represented in Fig. 4Fig. 5, it is possible to observe changes in absorption profiles of the scan spectrum samples, and it has been associated by other compounds such as quinones, caramelans, caramelens and caramelins (Palashudin‐Sk et al., 2012; Zhang et al., 2015; Golon and Kuhnert, 2013; Golon and Kuhnert, 2012), which also change the color of the samples and are responsible for the characteristic caramel. There is a clear observation that the higher the reaction time in this case was analyzed in time 0, 24 and 96 h, the greater the change into spectra profiles; and the higher the temperature was, which was the formation of pigmented compounds,the more samples were marked,. ...
Article
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There are many reports of problems caused by incorrect storage of sugar production ‐ hardening, caking, dimming, losses and fires. Given the importance of crystal sugar, one of the main sugarcane‐based products in Latin America or around the World, there is a growing realization of work to increase efficiency and avoid losses in the manufacturing. However, during sugar storage, it is known that environmental factors (temperature, humidity, light and weather) influence the quality of the final product – several types of crystal sugars, such as: very high polarization (VHP); very‐very high polarization (V‐ VHP), and whites – Types 1, 2, 3 or 4. During storage, the temperature must be not exceed and/or sensitive to variations. The optimum relative humidity is 55‐65% with the maximum equilibrium moisture at 65%. This work aimed to assess which factors are important to accentuate the color during the storage process (specially, ICUMSA color and sucrose hydrolysis) of white sugar (Type 1). The results of the amounts of reducing sugars and ICUMSA color were evaluated by the response surface. It was concluded that there were changes in the amounts of reducing sugars, sucrose and ICUMSA color in the analyzed samples, that moisture is the most decisive factor. Therefore, it became clear that you should avoid such conditions of high humidity and temperature in storage sugar, in order to preserve the quality, which is highly perishable.
... The fact that Lamaming et al. (2013) observed strong increases in strength when adding glucose and sucrose before the hot-pressing of particleboard helps to dispel any expectation that an initial polymeric structure is required for effective bonding. Rather, such results are consistent with the mechanisms described earlier with respect to hemicellulose, where reactions among active forms of lower-mass compounds appear to play a role (Golon and Kuhnert 2012;Pintiaux et al. 2015). Temperatures above 180 C appear to be able to cure the sugar-based bonding system, leading to significantly higher strength properties, in addition to reductions in water absorption and thickness swelling (Lamaming et al. 2013). ...
Article
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The production of fiberboard, particleboard, and related hot-pressed biomass products can convert small, relatively low-valued pieces of wood into valuable products. There is strong interest in being able to manufacture such products without the addition of formaldehyde, which is a health hazard during both production and use. This article reviews literature describing various challenges that need to be faced in order to achieve satisfactory bonding properties in hot-pressed bio-based board products without the addition of formaldehyde. Bonding mechanisms are examined in the form of a hypothesis, in which the strength development is represented by a chain with four links. Failure of a board is expected to occur at the weakest of these mechanistic links, which include mechanical contact, molecular-scale wetting and contact, various chemical-based linkages, and structural integrity. The most promising technologies for environmentally friendly production of hot-pressed board with use of lignocellulosic materials tend to be those that favor success in the development of at least three of the mechanistic links in the hypothetical chain.
... However, they are also involved in the formation of new polysaccharides through non-enzymatic transglycosylation reactions (TGRs) induced by roasting (Moreira, Coimbra, Nunes, & Domingues, 2013;Moreira, Coimbra, Nunes, Simões, & Domingues, 2011;Moreira et al., 2016;Moreira et al., 2014). This follows the pattern described for other carbohydrates, namely starch Siljeström, Björck, & Westerlund, 1989), malto-oligosaccharides (Hollnagel & Kroh, 2000;Nunes et al., 2016), and sucrose (Golon & Kuhnert, 2012), when submitted to thermal processing under low moisture content. A model system composed of a mixture of (a1?5)-L-arabinotriose (Ara 3 ), an oligosaccharide structurally related to the coffee arabinogalactans, and 5-O-caffeoylquinic acid (5-CQA), the most abundant phenolic compound in green coffee beans, showed that chlorogenic acids (CGAs) can be ester and glycosidically-linked to carbohydrates during thermal treatment (Moreira et al., 2015). ...
Article
Under roasting conditions, polysaccharides depolymerize and also are able to polymerize, forming new polymers through non-enzymatic transglycosylation reactions (TGRs). TGRs can also occur between carbohydrates and aglycones, such as the phenolic compounds present in daily consumed foods like coffee. In this study, glycosidically linked phenolic compounds were quantified in coffee melanoidins, the polymeric nitrogenous brown-colored compounds formed during roasting, defined as end-products of Maillard reaction. One third of the phenolics present were in glycosidically linked form. In addition, the roasting of solid state mixtures mimicking coffee beans composition allowed the conclusion that proteins play a regulatory role in TGRs extension and, consequently, modulate melanoidins composition. Overall, the results obtained showed that TGRs are a main mechanism of phenolics incorporation in melanoidins and are inhibited by amino groups through Maillard reaction.
... They could identify a series of homologous oligomers of up to six monomeric units of carbohydrates bound through glycosidic bonds and their dehydration products. 16 In Maillard model systems with several different carbohydrates and amino acids they could show the formation of oligomers of similar structure and in addition the formation of products consisting of carbohydrates and amino acids. 17 The aim of the present study was to bring new insights into the structure of melanoidins formed during the Maillard reaction. ...
Article
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Melanoidins are formed in foods during processing through the Maillard reaction between carbohydrates and amino compounds. The aim of this study was to draw conclusions about the formation mechanism and the structure of melanoidins formed at low water contents and low temperatures. In the Maillard reaction of d-glucose and γ-aminobutyric acid at low water contents 3-deoxyglucosone is the most important intermediate. Therefore, we used the reaction of 3-deoxyglucosone with γ-aminobutyric acid or β-alanine as a simplified model system. The degradation of 3-deoxyglucosone and the color formation of the formed melanoidins were determined. In addition, the reaction mixture was analyzed with high-resolution mass spectrometry and a Kendrick analysis was applied. Oligomers consisting of up to four molecules of 3-deoxyglucosone and three amino acids and their respective dehydration products with furanoidic structure were detected. The melanoidin structure of C-C linked monomeric units postulated by Kroh et al. could be confirmed.
... Caramel is mainly produced by heating a mixture of sucrose (or saccharose), lactose and, maltose and used in traditional cooking, backing and food additive for coloring. While heating the mixture for caramel production, lactose breaks down to monosaccharide units whereas sucrose and maltose remain abundant in caramel being thermally more stable [46,47]. Therefore, significantly higher levels of sucrose in red cooking, mushroom flavored and dark soy sauce indicate the high caramel addition in the final product, and suggest that sucrose is a widely used source for caramel in China. ...
... Two important roles of caramelisation in the food industry are caramel flavour and caramel colour. This reaction produces an irreversible complex combination of compounds making caramel categorisation difficult(Golon and Kuhnert 2012, Zhang et al. 2013). ...
Research
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Recent research into the thermal behaviour of sucrose suggests a possibility to hold sucrose at low temperatures without the sucrose crystal changing state, therefore retaining its functionality. The functionality of sucrose is essential for ensuring a desirable cake texture. Studying the structure of a cake determines if holding sucrose at low temperatures to achieve a caramelised flavour affects the functionality of the sucrose within a cake. This dissertation fills the gap in literature by applying recent research into the thermal behaviour of sucrose to a manufacturing and bakery application looking into the benefits, detectability, acceptability, feasibility and structural functionality differences. To compare the functionality of sucrose at increasing degrees of degradation, cakes were made containing sucrose held at 150°C for 2 and 3 hours and compared to a control sample. A sensory test determined a significant difference in the detection of caramelised flavour with little noticeable difference between the textural analysis and structural C-cell analysis of the cake samples. Thermally decomposed sucrose will not lower the pH of batters and doughs enabling it to be used in pH-sensitive recipes and will reduce the need to include caramel additives; all of which provide innovation opportunities and a greater understanding into the functionality, behaviour and versatility of sucrose in bakery products.
... Caramel dyes are used in several foodstuffs, including processed meats. They consist of complex mixtures made from the heating of aldoses with acids, alkalis, and salts (Chappel & Howell, 1992;Golon & Kuhnert, 2012). In the processing of the classes III (E150c, ammonia process) and IV (E150d, ammonia-sulfite process) synthetic caramel dyes, low molecular mass compounds with carcinogenic properties can be generated, such as the 4-methylimidazole (4-MEI), its structural isomer 2-methylimidazole (2-MEI), and the 2-acetyl-4-tetra-hydroxibutylimidazole (THI) (JECFA, 2011;NTP, 2007;Vollmuth, 2018) ( Table 1). ...
Article
Meat products are important for balanced diets because of their nutritional richness. However, noxious compounds may be formed by interactions among reactants and specific conditions in processed meats. N-nitroso compounds, heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, 1,4-dinitro-2-methyl pyrrole (DNMP), and ethyl nitrolic acid (ENA) are among the main compounds of toxicological concern. This review corroborates the International Agency for Research on Cancer (IARC)'s decision to classify those foodstuffs as carcinogenic to humans. Furthermore, this paper also aimed at clarifying how noxious compounds are formed in meat products, as well as their health effects for consumers. The preservatives abuse and the use of forbidden additives may increase the formation of carcinogens. Risks are not only due to preservatives, since some compounds are formed during processing or digestion, without clear link to any additive. Regulation should set specific residue limits for other noxious compounds in meat products, such as DNMP and ENA. The scope of control programs should be extended instead of assessing the proper use of additives only. Thus, reliable analytical methods for the quantitation of carcinogens should be available. Fermentative and enzymatic processes for bioconversion are among the main strategies to solve these problems in foodstuffs. The use of antioxidants is the most common approach, because of its low cost and effectiveness. In the future, the IARC classification should rather consider different categories of processing, as well as the chemical and microbiological composition of meat products. Further studies are still required to clarify the increase on cancer risk due to the consumption of meat products and to elucidate the main mechanisms of carcinogenicity. Notwithstanding, such carcinogens cannot be neglected, but continuously investigated, including their health implications in relation to other foods.
... Caramel is one of the most worldwide consumed additives and is produced by heating carbohydrates from vegetable sources (glucose, sucrose, invert sugar, etc.) in the presence of caramelisation promoters (ammonia or ammonium in class III and IV, respectively). The result is a complex mixture which is responsible for the aromatic and colourant characters of caramels [7,8], and it has been used in food and beverages to provide some properties such as colour, taste, smell and texture, and for its ability for stabilisation of colloidal systems, as well as for its emulsifying properties, facilitating the dispersion of water-insoluble materials, retarding flavour changes and preserving the shelf-life of beverages exposed to light [9]. Besides these, caramel has recently also been highlighted as beneficial in nonenzymatic browning inhibition [10]. ...
Article
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Nutraceutical activity of food is analysed to promote the healthy characteristics of diet where additives are highly used. Caramel is one of the most worldwide consumed additives and it is produced by heating natural carbohydrates. The aim of this study was to evaluate the food safety and the possible nutraceutical potential of caramel colour class IV (CAR). For this purpose, in vivo toxicity/antitoxicity, genotoxicity/antigenotoxicity and longevity assays were performed using the Drosophila melanogaster model. In addition, cytotoxicity, internucleosomal DNA fragmentation, single cell gel electrophoresis and methylation status assays were conducted in the in vitro HL-60 human leukaemia cell line. Our results reported that CAR was neither toxic nor genotoxic and showed antigenotoxic effects in Drosophila. Furthermore, CAR induced cytotoxicity and hipomethylated sat-α repetitive element using HL-60 cell line. In conclusion, the food safety of CAR was demonstrated, since Lethal Dose 50 (LD50) was not reached in toxicity assay and any of the tested concentrations induced mutation rates higher than that of the concurrent control in D. melanogaster. On the other hand, CAR protected DNA from oxidative stress provided by hydrogen peroxide in Drosophila. Moreover, CAR showed chemopreventive activity and modified the methylation status of HL-60 cell line. Nevertheless, much more information about the mechanisms of gene therapies related to epigenetic modulation by food is necessary.
... In resume, the MS data showed that the dry heating of OS and PS samples caused not only depolymerization but also dehydration, effects which are described in the literature for similar compounds (Chiku, Nishimoto, & Kitaoka, 2010;Čmelík & Chmelík, 2010;Golon, González, Dávalos, & Kuhnert, 2013). In the case of OS samples, it was also able to induce polymerization (Moreira et al., 2011) and confirmed by Golon and Kuhnert (2012). In the case of thermal treated PS samples, evidences were also gathered proving the existence of structural changes affecting the activity of the enzyme ␣-amylase, could be will be clarified by ESI-CID-MS/MS data. ...
... On the other hand, glucose oligomerization by condensation reactions forms strongly colored nonvolatile components of relatively high molar mass, which are classified into three classes: caramelans, tetramers of hexoses (C 24 [41]. It is worth to point out that the molecular formula of these structures depends on the type of carbohydrate used and, furthermore, intermediate products composed by dimers or trimers are also formed [42]. Moreover, as the caramelization time increases, and hence dehydration reactions, the formed furan compounds HMF, furfural and HAF may act as precursors of coloring polymeric products [32]. ...
... This very particular behavior is certainly attributable to the in situ resin generated by reactions (decomposition and recondensation) of free sugars induced by high temperature. These include thousands of reaction oligomer products having up to 6 carbohydrates units and reactive furfural derivatives units (Golon and Kuhnert 2012). ...
Article
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As the worldwide demand for fuels and materials increases, fossil resources are decreasing and global warming is a concern, and thus the need for alternative solutions is high. In the industries of furniture and housing, particleboards are interesting materials, as they reutilize wastes from other industries (wood, agriculture) although they also rely on chemical binders that are petroleum-based and toxic. A very promising alternative is then clearly identified in finding ways to produce binderless boards and associated materials. This review considers the state of the art in the field of binderless board production, and other processes making it possible to turn raw plant fibers into structural materials without using any external chemistry. The mechanical properties and water resistance are collected and compared. Identified chemistry changes occurring during the thermo-compressive process are discussed with an aim towards understanding of the mechanisms of cohesion.
... Figure 2 shows pecan oil-DL candies color parameters. In agreement with Gaze et al. (2015), positive values of a* and b* indicated a tendency to red-yellow products with a predominance of b* in all samples, due to browning by Maillard and caramelization reactions (Golon & Kuhnert, 2012;Pathare et al., 2013). Drying method moistly affected color parameters, resulting in lower L* for both VD and FD products, lower a* and much lower b* values for FD products concerning controls. ...
Article
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For the development of gelatinized dairy products that include emulsified pecan oil as an unsaturated fatty acid source the incorporation of hydrocolloids becomes necessary and their properties must be carefully selected. This work aimed to study gelatinized candies made with 0% milk fat dulce de leche with pre-emulsified pecan nut oil using combinations of gelatin (4.67 to 7 g/100 g) and high methoxyl pectin (1.33 to 2 g/100 g) as gelling agents. The effect of different drying methods (vacuum-oven at 35 °C for 24 h and freeze-drying) was evaluated. Control samples without drying were also studied. Dehydration conditions significantly (p < 0.05) affected aw, texture (hardness, cohesiveness, adhesiveness, gumminess, springiness, and resilience) and color parameters (L*, a*, b*) of products, being higher than the effect of the gelling agent. Formulations were selected based on texture and aw criteria and sensory evaluated by appearance, color, texture, taste, and overall acceptability. Two formulations (one with 7% gelatin and 1.33% high methoxyl pectin content, and the other with 2% high methoxyl pectin and 4.67% gelatin content), both with low moisture content and vacuum-dried, exhibited good acceptability. These pecan oil-dulce de leche gummy candies would represent a healthier candy version, low in saturated fatty acids, and source of oleic acid.
... Кроме того, активность воды, которая регулируется влажностью и составом, влияет на срок годности карамели. Обычно карамель содержит 0,5-4% молока в зависимости от ее вида [8]. Молочные продукты придают карамельной массе вкус, цвет и аромат, которые образуются в результате реакции Майяра между белками молока и моносахарами. ...
... Caramels are produced by heating carbohydrates from vegetable sources (glucose, sucrose, invert sugar, etc.) in the presence or not of caramelization promoters (acids, alkalis, ammonium or sulfite compounds). The caramelization process includes a multitude of chemical reactions leading to the formation of a complex mixture of molecules, with low molecular weight ones responsible for the aromatic feature and high molecular weight ones (melanoidins) responsible for the colourant feature of caramels (Golon & Kuhnert, 2012;Licht et al., 1992;Moretton, 2009;Sengar & Sharma, 2014). These reactions are specific in heat treatments and nature of the used sugar. ...
Article
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Caramel is one of the most current additive/ingredient obtained by controlled heat treatment of carbohydrates. A combination of in vitro and in vivo methods showed that aromatic caramels and caramel colours are antioxidant. The highest value is obtained for Class III caramel colours for in vitro TEAC and KRL tests (401 µmol Trolox equivalent/g and 5 366 mg gallic acid equivalent/100 g, respectively). In in vivo test, caramels also increase the resistance of C. elegans to oxidant attack, with until 40% live worms after 18 h of treatment in the presence of caramels against no live worms after 12 h of treatment without. In conclusion, this study explore benefit effect of caramels and showed an antioxidant activity linked to their color intensity. The molecules involved remain to be explored.
... Caramel colors, one of the most widely used dietary additives, have been classified as four distinct types by their processing (Chappel & Howell, 1992;Golon & Kuhnert, 2012). With the participation of ammonia and ammonium salts, type III and type IV caramels can be manufactured through both Maillard and caramel reactions. ...
Article
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To study the caramel reactions of disaccharides with water, the type I maltose caramel products (MCPs) and sucrose caramel products (SCPs) at three reaction stages were yielded and their reaction rates, UV absorptions, flavor compounds, and antioxidant activities were also detected. It was found that the caramel reactions of sucrose were faster than those of maltose and their reaction rates quickly increased to a high level in the middle stage. UV absorption of SCP in the late stage at 305 nm was much stronger than those of MCPs. Both the MCP and SCP obtained at 180 °C and 4 min had the highest concentrations of 5-hydroxymethylfurfural and total flavor compounds. Moreover, the total flavor concentrations of SCPs were much larger than those of MCPs and the antioxidant effects of SCPs were also stronger. Thus, a preferred condition for both two disaccharide caramel reactions was suggested at 180 °C for 4 min and the sucrose caramels could give better flavors than maltose caramels.
... Lost-sucrose casting Besides using wax materials, a new approach was created by using a caramel material, shown in Figure 3. The caramel is composed from several thousand compounds formed by a small number of unselective and chemoselective reactions, including 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 and colored aromatic products (Kuhnert, 2012). For simplification from now on, this material will be called just "sucrose". ...
... Caramel is normally manufactured by heating a combination of maltose, lactose, and sucrose. During heating lactose splits into monomers while sucrose and maltose remain in abundance (Golon andKuhnert, 2012, Kuhnert et al., 2010). Along with the sucrose produced during fermentation, the caramel in CS caused a sig- ...
Article
Organic foods gaining popularity due its connection with the health, high nutritional value, and high quality. Therefore, it is of prime importance to develop the analytical methods to combat with food authentication and protect consumer from the food fraud. Conventional soy sauce (CS) and organic soy sauce (OS) were characterized and differentiate for the first time using ¹H NMR-based metabolomics approach. Classification methods like orthogonal partial least squares of discriminant analysis (OPLS-DA) showed a significant (p<0.01) separation among CS and OS yielding important metabolites contributing towards this separation. OS was characterized by increased levels of leucine, threonine, isoleucine, valine, choline, phenylalanine, tyrosine, lactate, and acetate whereas, CS showed elevated concentrations of glutamate, glucose, and sucrose. The abundance ratio of ¹³C to ¹²C was determined by ¹H-NMR spectroscopy which showed an increased ratio of ¹³C isotope in OS samples indicating the organically grown wheat and soybean used for the preparation of OS. The results can be helpful to convey the information to the end-user to prevent them from economically motivated adulteration. This information could also pave the way to further trace and authenticate the raw materials used in the production of soy.
... Although the mechanism of formation of melanoidins by the polymerization of dicarbonyl compounds had been recognized, there are still differences in the identified results due to the differences in experimental methods. To date, the confirmed structural units are furan and amino acids [3], 3-DG and amino acids [23], methyl pyrrole [30], glyoxylic acid and glyoxal [16], and hydration products of sugar oligomers [31]. Although some structural units had been identified, none of these basic structural units could be combined to form the polymers that have been detected in foods with MW intervals of 72-74 Da. ...
Article
To decipher the formation mechanism of nitrogen-free substructures in melanoidins, methylglyoxal or 3-Deoxyglucosone was used as a substrate to react by aldol reaction under different pH conditionst. The obtained products were characterised by chromatography, mass spectrometry, and spectroscopic methods. Overall, the molecular weights of the polymer structural units varied mainly within 54–56 and 72–74 Da, respectively, due to the different dehydration extent of β-hydroxy aldehyde or ketones, and uneven reduction by NaBH4. Moreover, the nitrogen-free substructures formed by this reaction can cross-link with gluten and dextran to form melanoidins. Therefore, the nitrogen-free substructures by this reaction to formed with units of 54–56 and 72–74 Da, which are similar as the typical polymers in food melanoidin. It is inferred that the typical polymers in food may also be formed by this pathway and which can be used as a detectable biomarker in melanoidins
... Parallel to the MR the amino acids may form dipeptides, cyclopeptides or other still unknown linkages without involvement of the carbohydrate [8,9]. In the absence of amino acids, carbohydrates undergo caramelization reactions and eventually form colorants based on transglycosidation reactions [10] or based on polymerization of the dehydration product 3-DG [11,12]. Because of the multitude of involved reaction products that might be integrated in the melanoidin backbone in the course of the MR studies that help to cluster and classify possible end products based on different reaction conditions, it is necessary to investigate the composition of melanoidins and to better understand their role in food quality, for example, the flavors, colors and antioxidant properties [13][14][15]. ...
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The chemical composition of melanoidins formed from glucose (Glc) and alanine (Ala) in different molar ratios was investigated using UV/Vis, FTIR, EPR spectroscopy and elemental analysis (EA). Melanoidin samples were prepared at varying molar ratios of Glc and Ala ranging from 10:1 to 1:10 (Glc:Ala). Reaction systems containing a higher molar ratio of Ala show higher melanoidin yields and higher UV/Vis absorbance. This indicates that an excess of Ala facilitates the formation of larger π-electron systems and catalyzes the melanoidin formation. EPR spectroscopy showed more radicals in Ala enriched samples. The EA data suggest that during the formation of melanoidin from Glc and Ala higher amounts of amino acid support dehydration of the reaction products. On the basis of our data, we postulate the structures of products and intermediates for the reaction at different Glc/Ala ratios. PCA of the FTIR spectra allows to separate different melanoidin samples formed at varying molar ratios indicating their different molecular compositions.
Chapter
Sweeteners are the primary ingredients in the manufacture of confections. Chemically, the primary sweeteners in confections are carbohydrates, which consist of a group of widely varied chemical substances present in both plants and animals. For example, in dry corn, approximately 55% of the solids are carbohydrates. The word “carbohydrates” itself means hydrated carbon. Thus, carbohydrate chemistry mostly deals with chains of carbon atoms hydrated with water, with a general formula of Cx(H2O)y.
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This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SO3H groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural.
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Effects of carbohydrates including glucose, sucrose, maltose, mannitol, and starch on the oxidative stability of corn oils were evaluated at 40 A degrees C for 51 days, at 100 A degrees C for 17 h, and at 180 A degrees C for 90 min. The degree of oxidation was determined by headspace oxygen content, conjugated dienoic acid (CDA) assay, or p-anisidine value (p-AV) and the moisture content of the oils was analyzed. Starch showed pro-oxidant properties whereas mannitol acted as an antioxidant at all tested temperatures. However, glucose, sucrose, and maltose showed different properties depending on the temperature and type of assays. At 40 A degrees C, glucose, sucrose, and maltose showed antioxidant properties in headspace oxygen and CDA assays. There were no significant differences in CDA between samples at 100 and 180 A degrees C. p-AV in samples containing glucose were significantly higher than those in controls at 180 A degrees C, which may be due to the formation of volatiles from caramelization rather than lipid oxidation. Moisture content of oils containing glucose and starch was significantly higher than that of controls, whereas that of oils containing mannitol was lower than in the control (p < 0.05). Changes in moisture content of oils may be due to the migration of moisture from added carbohydrates into the oils.
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(-)-Quinic acid possess eight possible stereoisomers, which occur both naturally and as products of thermal food processing. In this contribution, we have selectively synthesized four isomers namely, epi-quinic acid, muco-quinic acid, cis-quinic acid and scyllo-quinic acid in order to develop a tandem LC-MS method identifying all stereoisomeric quinic acids. Four derivatives have been unambiguously characterized by single crystal X-ray crystallography. The missing diastereoisomers of quinic acid were obtained by non-selective isomerization of (-)-quinic acid using acetic acid/conc. H2SO4 allowing chromatographic separation and assignment of all diastereoisomers of quinic acid. We report for the first time that a full set of stereoisomers are reliably distinguishable on the basis of their tandem mass spectrometrical fragment spectra as well as their elution order. A rational for characteristic fragmentation mechanisms is proposed. In this study, we also observed that muco-quinic acid , scyllo-quinic acid and epi-quinic acid are present in hydrolyzed Guatemala roasted coffee sample as possible products of roasting.
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A convenient, efficient, and cost-effective approach to the facile enzymatic production of difructose dianhydride (DFA) III from sucrose is described. Inulosucrase and inulin fructotransferase are used for inulin biosynthesis from sucrose and inulin decomposition to DFA III, respectively. Yeast treatment and preparative chromatography are used for the production purification. This method enables the large-scale preparation of difficult-to-access DFA III from the common and cheap starting material sucrose with high yield and purity.
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A colorimetric point-of-care paper-based analytical device (PAD) is developed for detecting adulterated beverages using whiskey falsified with caramel color as a model. Combining principal component analysis and calibration curves facilitated identification of adulteration in samples seized by the Brazilian Federal Police, at only B$0.02 per sample.
Chapter
Spirits stored in wooden barrels “mature” over time: in addition to color change, certain negative characteristics diminish, and new beneficial characteristics develop. Slight changes occur when spirits are stored in glass bottles, but these are negligible compared to the changes occurring in barrels. Consequently, maturation is intimately related to the chemistry and transport properties of wood.
Chapter
Color compounds constitute a unique class in that they are structurally diverse, and the chemical and physical properties are extremely complex. For many color compounds, their chromophoretic properties can only be adequately explained by referring to their molecular orbital structures.
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We fed rats noodle (N) -diet containing 30 wt.% instant noodle with a 26% fat-to-energy ratio for 30 days (N-group). Compared with rats that were fed the same amount of nutrients (C-group), the N-group showed lower liver triacylglycerol levels and higher fecal cholesterol levels. We then analyzed transcriptome of the hypothalamic–pituitary (HP), the liver and the white adipose tissue (WAT). Thyroid stimulating hormone (Tshb), and its partner, glycoprotein hormone genes were up-regulated in the HP of N-group. Sterol regulatory element binding transcription factors were activated in the liver of N-group, while an up-regulation of the angiogenic signal occurred in the WAT of N-group. N-group showed higher urine noradrenaline (NA) level suggesting that these tissue signals are regulated by NA and Tshb. The N-diet contains 0.326 wt.% glutamate, 0.00236 wt.% 6-shogaol and Maillard reaction products. Our results suggest that these ingredients may affect lipid homeostasis via the HP axis.
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Low-cost and nontoxic fluorescent reagents are important for on-site analysis performed by non-professionals. In this work, a cheap and widely available food additive, caramel was used as an effective fluorescence reagent for the sensitive detection of 2,4,6-trinitrophenol (TNP), 2,4-dinitrophenol (DNP) and 4-nitrophenol (4-NP). Through a simple dialysis, fluorescent components of a commercial caramel were harvested with a yield as high as 60%. The structural characterization demonstrated that the fluorescent components were dehydrated oligomers of carbohydrates. Their fluorescence can be quenched by these nitrophenols. The quenching mechanism was speculated as inner filter effect. At pH 8, a linear range of 0.2–22 μM and a detection limit of 90 nM could be achieved for TNP. Based on the difference of their quenching efficiency at different pHs, TNP, DNP and 4-NP can be simultaneously determined by solving the linear equations obtained at pH 3, 5 and 8. Successful detection of these nitrophenols in the water and soil samples was performed with relative standard deviations of 1.1–5.9% and recoveries of 95–108% of spiked standards.
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Caramel is a widely used water-soluble food pigment. The acylation of caramel was conducted by aliphatic acyl chlorides with different chain lengths. Acetyl, butyryl, octyl, lauryl, palmityl and stearyl caramels were prepared with the ratio of acyl chloride to caramel of 6. The formation of acylated caramel was confirmed by FT-IR spectra and the acyl mass fraction in acylcaramel was determined by potentiometric titration. Thermal analysis showed that the weight-loss of acylated caramel was higher than that of the raw caramel. The SEM analysis showed that the morphology of acylated caramel was significantly different from that of raw material. The acyl mass fraction of acylated caramel increased with the increase of acyl chain lengths. Meanwhile, the lipo-hydro partition coefficient, the solubility in corn oil, color, red and yellow indexes increased with the increase of mass fraction of acyl in acylcaramel. It was found that stearyl caramel has the highest lipid solubility of 5.73 mg/mL in corn oil, however, the color, red and yellow indexes of palmityl caramel reached 25818.60, 1.149 and 1.757 respectively. This study provides a method to improve the solubility of caramel in lipid phase and expand the application range of caramel.
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A central question in origins of life research is how non-entailed chemical processes, which simply dissipate chemical energy because they can do so due to immediate reaction kinetics and thermodynamics, enabled the origin of highly-entailed ones, in which concatenated kinetically and thermodynamically favorable processes enhanced some processes over others. Some degree of molecular complexity likely had to be supplied by environmental processes to produce entailed self-replicating processes. The origin of entailment, therefore, must connect to fundamental chemistry that builds molecular complexity. We present here an open-source chemoinformatic workflow to model abiological chemistry to discover such entailment. This pipeline automates generation of chemical reaction networks and their analysis to discover novel compounds and autocatalytic processes. We demonstrate this pipeline's capabilities against a well-studied model system by vetting it against experimental data. This workflow can enable rapid identification of products of complex chemistries and their underlying synthetic relationships to help identify autocatalysis, and potentially self-organization, in such systems. The algorithms used in this study are open-source and reconfigurable by other user-developed workflows.
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In this contribution we investigate the thermal decomposition of four pentapeptides containing a tryptophan moiety. Pentapeptides were heated at 220°C and the resulting reaction mixtures investigated by HPLC coupled to high resolution mass spectrometry and tandem mass spectrometry. A total of 95 thermal decomposition products could be observed and resolved by chromatography. In detail we report on the structure assignment of two types of reaction products common to investigated peptides and introduce two decomposition mechanisms. Pentapeptides react with oxygen to produce hydroxyl-tryptophan derivatives. In addition we observe the C-terminal decarboxylation of two peptides to form N-acyl tryptamine derivatives.
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A mixture of glucosamine (GlcN, 15% w/v) and different amino acids in 1:1 M ratio was incubated at 70 °C for 12 h. The resulting GlcN-amino acid caramels were analysed for α-dicarbonyl compounds, polyhydroxyalkyl pyrazines, heterocyclic compound and alkylimidazoles. All the analyses were performed by using HPLC-MS/MS followed by pooling the variables with principal component analysis (PCA). GlcN-Gly caramels generated the greatest amount of butterscotch aromatic compound diacetyl and polyhydroxyalkyl pyrazines (fructosazine and deoxyfructosazine). The potentially toxic heterocyclic compound, 5-hydroxymethylfurfural (HMF) was generated in greater amounts with the GlcN-Arg caramels. However, the toxic alkylimidazoles (4-MEI and THI) were not present in any of the GlcN-amino acid caramels. The results suggest that caramel with butterscotch aroma and bioactivity can be produced with GlcN-amino acid at 70 °C. The PCA performed discriminated the majority of the GlcN-amino acid combinations; GlcN-Gly and GlcN-Ser were best discriminated.
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Thermal treatment of food leads to the formation of melanoidins by reactions of carbohydrates with free amino acids or proteins in the late stage of Maillard reaction. The aim of this study was the identification of reaction mechanisms responsible for the formation of melanoidins involving active methylenes with heterocyclic structure and the structural characterization of the resulting products. For this purpose, norfuraneol was incubated with the aldehydes pyrrole-2-aldehyde or furfural at 125 °C. With the help of high resolution mass spectrometry the structural composition of oligomers of up to fifteen C5-units could be described for the first time. Aldol and Michael reactions could be identified as crucial steps for the formation of new C-C-bonds. With increasing heating time the elimination of water from the products was facilitated and oxidation reactions of integrated reductone structures lead to the expansion of conjugated double-bond systems responsible for the color formation of the samples.
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Quinic acid possess eight possible stereoisomers, which occur both naturally and as products of thermal food processing. In this contribution, we have selectively synthesized four isomers, namely, epi-quinic acid, muco-quinic acid, cis-quinic acid, and scyllo-quinic acid, to develop a tandem LC-MS method identifying all stereoisomeric quinic acids. Four derivatives have been unambiguously characterized by single-crystal X-ray crystallography. The missing diastereomers of quinic acid were obtained by nonselective isomerization of (−)-quinic acid using acetic acid/concentrated H 2 SO 4 allowing chromatographic separation and assignment of all diastereomers of quinic acid. We report for the first time that a full set of stereoisomers are reliably distinguishable on the basis of their tandem mass spectrometric fragment spectra as well as their elution order. A rationale for characteristic fragmentation mechanisms is proposed. In this study, we also observed that muco-quinic acid, scyllo-quinic acid, and epi-quinic acid are present in hydrolyzed Guatemalan roasted coffee sample as possible products of roasting.
Thesis
Der Einsatz von thermischen Speichern bietet eine Möglichkeit, Effizienzsteigerungen in Prozesswärmeanwendungen im Temperaturbereich zwischen ca. 100 °C und 250 °C zu erzielen und damit den Ausstoß von CO2-Emissionen zu verringern. Beispiele für Prozesswärmeanwendungen sind Pasteurisierungs- oder Sterilisationsprozesse, eine Einsatzbranche ist z. B. die Lebensmittelindustrie. Bei Temperaturen über 100 °C kann Wasser nur als Druckwasserspeicher verwendet werden, was zu hohen Kosten führt. Alternative drucklose Wärmespeicher basieren z. B. auf Thermalöl, Gesteinen, Beton oder Keramiken, die alle eine geringe spezifische Wärmekapazität aufweisen. Eine weitere drucklose Alternative sind Latentwärmespeicher. Sie speichern Wärme im Phasenwechsel des Speichermediums, meist von fest nach flüssig. Dadurch speichern sie annähernd isotherm und weisen eine hohe Speicherdichte innerhalb einer geringen Temperaturdifferenz auf. Im Prozesswärmebereich sind derzeit nur wenige Latentwärmespeicherkonzepte vorhanden. Deshalb müssen einerseits Latentspeichermaterialien weiterentwickelt werden, andererseits müssen geeignete Wärmeübertrager zur Be- und Entladung des Speichers zur Verfügung stehen. In dieser Arbeit wird ein Latentwärmespeicher basierend auf durchströmten Platten, die bisher noch nicht in Latentwärmespeichern eingesetzt worden sind, untersucht. Als Latentspeichermaterial wird der Zuckeralkohol D-Mannitol verwendet. Dieser wird im Labormaßstab unter verschiedenen Randbedingungen auf seine thermische Stabilität und damit seine Eignung als Latentspeichermaterial untersucht. In Kontakt mit Sauerstoff zeigt das Material eine zu kurze Lebensdauer für die meisten Speicheranwendungen. In inerter Atmosphäre kann die thermische Stabilität erhöht werden. Deshalb hängt die Eignung in einer inerten Atmosphäre von der geforderten Lebensdauer des Materials in der Speicheranwendung ab. Ein Prototyp des Plattenspeichers wird in einem Teststand vermessen. Zum Verständnis der Vorgänge im Speicher wird ein detailliertes physikalisches Simulationsmodell erstellt, das mit Messdaten validiert wird. Weiterhin wird ein vereinfachtes Widerstands-Kapazitäten-Simultionsmodell erstellt, das eine um den Faktor 20 bis 30 schnellere Simulationszeit aufweist als das detaillierte Modell. Beide Modelle können die in der flüssigen Phase des Speichermaterials auftretende freie Konvektion während der Speicherbeladung simulieren. Ein Vergleich der beiden Modelle zeigt, dass das vereinfachte Modell das Verhalten des Speichers ausreichend genau darstellt, um es für Speicherauslegungen und -optimierungen verwenden zu können. Mit dem Widerstands-Kapazitäten-Modell wird eine Parametervariation durchgeführt. Die Ergebnisse zeigen, dass eine Variation des Plattenabstands und der Prozessparameter eine flexible Speicherauslegung zulässt und so unterschiedliche Werte für die charakteristischen Kenngrößen des Speichers erzielt werden können, um verschiedene Anwendungen zu bedienen. Um den Plattenspeicher mit dem Stand der Technik vergleichen zu können, wird weiterhin ein Lamellenwärmeübertrager mit dem gleichen Speichermaterial im Teststand vermessen, ein detailliertes physikalisches Modell sowie ein Widerstands-Kapazitäten-Modell erstellt und validiert. Ein simulativer Vergleich des Platten- mit dem Lamellenspeicher zeigt, dass sich die Kennwerte des Plattenspeichers in einer ähnlichen Größenordnung befinden wie die des Lamellenspeichers. Durch verschiedene Geometrieparameter können die Kenngrößen der beiden Speicher verändert werden, wodurch der eine oder der andere Speicher vorteilhafter für eine geforderte Anwendung sein kann.
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Sugars are ubiquitous in food, and are among the main sources of energy for almost all forms of life. Sugars can also form structural building blocks such as cellulose in plants. Because of their inherent degradability and biocompatibility characteristics, sugars are compelling materials for transient devices. Here, an additive manufacturing approach for the production of magnetic sugar‐based composites is introduced. First, it is shown that sugar‐based 3D architectures can be 3D printed by selective laser sintering. This method enables not only the caramelization chemistry but also the mechanical properties of the sugar architectures to be adjusted by varying the laser energy. It is also demonstrated that mixtures of sugar and magnetic particles can be processed as 3D composites. As a proof of concept, a sugar‐based millimeter‐scale helical swimmer, which is capable of corkscrew motion in a solution with a viscosity comparable to those of biological fluids, is fabricated. The millirobot quickly dissolves in water, while being manipulated through magnetic fields. The present fabrication method can pave the way to a new generation of transient sugar‐based small‐scale robots for minimally invasive procedures. Due to their rapid dissolution, sugars can be used as an intermediate step for transporting swarms of particles to specific target locations.
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Protein-metal association may occur in nutritional products, with consequences for organoleptic quality, nutrient stability, and metal bioavailability. Insights into protein-metal associations were obtained by “centrifugation analysis”: high speed centrifugation followed by determinations of protein and minerals in the serum (supernatant). Experimental data suggested that the distribution of iron in a dairy-based nutritional product emulsion could be modified by milk protein ingredient selection. Each serum mineral concentration (Ca, Cu, Fe, Mg, Mn, P, and Zn) was correlated with serum protein (R² = 0.95 to 0.99), and the association of a divalent metal with serum protein was correlated with its fortification rate. Iron and/or zinc association with serum protein increased with cysteine and/or native whey protein increases in nutritional products. Flavoring and/or coloring ingredients could alter serum mineral concentration. Strong correlations in the experimental data provide information upon which strategies could be formed for improving dairy-based nutritional product quality, stability, and performance.
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Supercritical water reforming (500–700 °C, 30 MPa) of different alcohols, including ethanol, glycerol and sorbitol as the components of plant raw materials revealed the common features and peculiarities depending on the nature of the substrate. It was found that glycerol and sorbitol demonstrate higher degrees of gasification under equal conditions compared to ethanol. In the case of ethanol, the methanation reaction occurs to a more significant extent than in the case of glycerol and sorbitol. The highest concentration of hydrogen in the gas products (up to 45%) was found for ethanol reforming due to the high H/C ratio in this substrate.
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In this study, the borate functionalized caramel (BF-Car) product was prepared by using glucose and synthesized ethanolamine borate ester through Caramel and Schiff base reaction. Then, BF-Car product was applied as effective intumescent flame retardant (FR) system to minimize the fire hazard of protein wool via the facile exhaustion technique. The adsorption performance, smoke and heat suppression capacity, thermal stability, flame retardancy and mechanism of the FR wool were investigated. The BF-Car treatment endowed brown color and good FR ability to wool fabric, and significantly inhibited smoke/heat emission of wool. The treated wool samples with a weight gain of 9.2% showed self-extinguish property, and still reached self-extinction after 5 home washings. The thermal stability analysis and char residue analyses suggested a condensed FR action for modified wool. The BF-Car treatment finely affected the softness and tensile strength of the fabric. The present prepared BF-Car material shows great possibility to act as sustainable chemicals for enhancing the fire safety of wool fabrics.
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Despite more than 100 years of research, formation of food melanoidins from carbohydrates and amino acids in the course of the Maillard reaction is still not fully understood. Experiments with relevant precursors are commonly used to limit the pathways of the complex reaction and to elucidate the formation mechanisms of the colored end-products. Here as a simple model, methylglyoxal was incubated with l-alanine or l-lysine in aqueous solutions at 100 °C and pH 5. The reaction mixtures were analyzed for color formation, molecular weight distribution, and conversion of methylglyoxal. High-resolution mass spectrometry was used to characterize the variety of products formed. With the help of Kendrick and van Krevelen analyses, the complex data sets were investigated for common substructures and reaction patterns. This study revealed that methylglyoxal forms oligomers via aldol reaction under involvement of its prevalent reaction products such as formaldehyde, acetaldehyde, acetol, and aminoacetone with amino acids.
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Fructans are the polymers of fructose molecules, normally having a sucrose unit at what would otherwise be the reducing terminus. Inulin and levan are two basic types of simple fructan, which contain β-(2, 1) and β-(2, 6) fructosyl-fructose linkage, respectively. Fructans not only can serve as soluble dietary fibers for food industry, but also may be biologically converted into high-value products, especially high-fructose syrup and fructo-oligosaccharides. In recent years, much attention has been focused on production of difructose dianhydrides (DFAs) from fructans. DFAs are cyclic disaccharides consisting of two fructose units with formation of two reciprocal glycosidic linkages. They are expected to have promising properties and beneficial effects on human health. DFAs can be produced from fructans by fructan fructotransferases. Inulin fructotransferase (IFTase) (DFA III-forming) and IFTase (DFA I-forming) catalyze the DFA III and DFA I production from inulin, respectively, and levan fructotransferase (LFTase) (DFA IV-forming) catalyzes the production of DFA IV from levan. In this article, the DFA-producing microorganisms are summarized, relevant studies on various DFAs-producing enzymes are reviewed, and especially, the comparisons of the enzymes are presented in detail.
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The caramel-like smelling compounds 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) were identified by GC−MS and GC−MS/MS in Maillard reaction systems based on pentoses. The reaction was performed in a phosphate buffer by heating xylose, ribose, or arabinose with glycine or l-alanine at 90 °C for 1 h. HEMF was detected in the system pentose/alanine. HDMF was formed in both pentose/glycine and pentose/alanine systems as well as directly from pentoses. Experiments using 13C-labeled glycine and alanine suggest the incorporation of the Strecker degradation products formaldehyde and acetaldehyde into the pentose moiety, forming the furanones HDMF and HEMF, respectively. The presence of 12C-HDMF, which was approximately 30% of the total HDMF amount found in xylose/glycine, indicates that HDMF is partly formed by sugar fragmentation. The proposed mechanism for the formation of the furanones is based on decomposition of the Amadori compound via 2,3-enolization, chain elongation by the Strecker aldehydes, and reduction of the resulting acetylformoin-type intermediates to the target molecules. Keywords: Maillard reaction; pentose model system; 4-hydroxy-2,5-dimethyl-3(2H)-furanone; 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone; GC−MS/MS
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Carbon particles are synthesized under hydrothermal conditions using different biomass (glucose, xylose, maltose, sucrose, amylopectin, starch) and biomass derivates (5-hydroxymethyl-furfural-1-aldehyde (HMF) and furfural) as carbon sources. Carbons obtained from mono-and polysaccharides, hexose and pentose sugars, and from the biomass derivatives, HMF and furfural, are compared from the particle morphology, chemical composition and structural point of view. A clear structural and morphological difference can be observed in carbons from pentoses and hexoses, but in the latter case, irrespective of the nature of the hexose sugar, all carbon materials showed astonishing similarities, opening the way for the use of renewable biomass in the synthesis of such carbon materials.
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The chlorogenic acids of mate (Ilex paraguariensis) have been investigated qualitatively by LC-MS(n). Forty-two chlorogenic acids were detected and all characterized to regioisomeric level on the basis of their fragmentation pattern in tandem MS spectra, 24 of them for the first time from this source. Both chlorogenic acids based on trans- and cis-cinnamic acid substituents were identified. Assignment to the level of individual regioisomers was possible for eight caffeoylquinic acids (1-8), five dicaffeoylquinic acids (20-24), six feruloylquinic acids (9-14), two diferuloyl quinic acids (25 and 26), five p-coumaroylquinic acids (15-19), four caffeoyl-p-coumaroylquinic acids (34-37), seven caffeoyl-feruloylquinic acids (27-33), three caffeoyl-sinapoylquinic acids (38-40), one tricaffeoylquinic acid (41), and one dicaffeoyl-feruloylquinic acid (42). Furthermore, four caffeoylshikimates (43-46), three dicaffeoylshikimates (47-49), one tricaffeoylshikimate (51), and one feruloylshikimate (50) have been detected and shown to possess characteristic tandem MS spectra and were assigned by comparison to reference standards.
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The emerging glycomics and glycoproteomics projects aim to characterize all forms of glycoproteins in different tissues and organisms. Tandem mass spectrometry (MS/MS) is the key experimental methodology for high-throughput glycan identification and characterization. Fragmentation of glycans from high energy collision-induced dissociation generates ions from glycosidic as well as internal cleavages. The cross-ring ions resulting from internal cleavages provide additional information that is important to reveal the type of linkage between monosaccharides. This information, however, is not incorporated into the current programs for analyzing glycan mass spectra. As a result, they can rarely distinguish from the mass spectra isomeric oligosaccharides, which have the same saccharide composition but different types of sequences, branches or linkages. In this paper, we describe a novel algorithm for glycan characterization using MS/MS. This algorithm consists of three steps. First, we develop a scoring scheme to identify potential bond linkages between monosaccharides, based on the appearance pattern of cross-ring ions. Next, we use a dynamic programming algorithm to determine the most probable oligosaccharide structures from the mass spectrum. Finally, we re-evaluate these oligosaccharide structures, taking into account the double fragmentation ions. We also show the preliminary results of testing our algorithm on several MS/MS spectra of oligosaccharides. The program GLYCH is available upon request from the authors.
Article
The caramel-like smelling compounds 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) were identified by GC-MS and GC-MS/MS in Maillard reaction systems based on pentoses. The reaction was performed in a phosphate buffer by heating xylose, ribose, or arabinose with glycine or L-alanine at 90 °C for 1 h. HEMF was detected in the system pentose/alanine. HDMF was formed in both pentose/glycine and pentose/ alanine systems as well as directly from pentoses. Experiments using 13C-labeled glycine and alanine suggest the incorporation of the Strecker degradation products formaldehyde and acetaldehyde into the pentose moiety, forming the furanones HDMF and HEMF, respectively. The presence of 12C-HDMF, which was approximately 30% of the total HDMF amount found in xylose/glycine, indicates that HDMF is partly formed by sugar fragmentation. The proposed mechanism for the formation of the furanones is based on decomposition of the Amadori compound via 2,3-enolization, chain elongation by the Strecker aldehydes, and reduction of the resulting acetylformoin-type intermediates to the target molecules.
Article
This chapter explains the decomposition of saccharides by heat devoted to the caramelization of saccharides and their pyrolysis above 250°. Caramelization belongs to the group of so-called “browning reactions.” Caramel has a brown color and it originates from various sugars when they are heated, either dry, or in concentrated solutions. The quality of a caramel depends on its source as well as on the parameters of the process of its manufacture. Caramel is manufactured to change and improve the appearance (color) of many food products; the enhancement of the flavor of food is also important. The chemical nature of caramel depends on the conditions of the caramelization and the source, at least in the terminal period of their processing. Ever since it was suspected that caramels are biologically active, the daily uptake levels for them have been calculated and announced. The pyrolysis of sugars has been studied because carbohydrates could be considered as a source of technically important products. Moreover, these studies were intended to contribute to the knowledge of the chemistry of caramelization.
Article
Difructose anhydrides (DFAs) are pseudodisaccharides produced by condensation of two fructose molecules by means of caramelization reaction which takes place during heating of sugars or sugar-rich foodstuffs. The aim of this research was to evaluate the feasibility of DFAs as chemical markers of honey authenticity and sugar-roasted torrefacto coffee. DFAs were analysed by gas chromatography coupled to mass spectrometry after conversion to their trimethylsilyl (TMS) derivatives. α-d-fructofuranoside-1,2′:2,1′-α-d-fructofuranoside (DFA7) and α-d-fructofuranoside-1,2′:2,1′-β-d-fructopyranoside (DFA9) can be used as quality markers of honey and coffee. DFA7 and DFA9 were detected in honey added with 5% fructose and sucrose caramels and 15% of glucose caramels. Torrefacto coffees showed DFAs values ranged from 0.195 to 0.570 g/100 g whereas only traces were found in natural roasted coffees. Quantities from 0.073 to 0.189 g/100 g were measured in blends of natural and torrefacto roasted coffees. A relationship between DFAs content in torrefacto coffees and roasting conditions was observed. In conclusion, this study indicated that DFAs are useful chemical indicators to control honey authenticity and torrefacto coffee roasting.
Article
The decomposition of sugars leads to the formation of volatile (caramel aroma) and brown-coloured compounds (caramel colours). The reaction can be effected by heat and is catalysed by acids and bases. The colours and aromas depend on the sugar used (i.e. whether mono-, oligo- or polysaccharide) and are formed mostly through deoxyosuloses, O-heterocyclic and carbocyclic intermediates as well as low-molecular-weight sugar fragments. The typical caramel aromas are traced back to cyclopentanone (cyclotene) and hydroxymethylfuranone (furaneol) and their formation and analysis, discussed. The structures of coloured products of caramelisation are still not fully understood. The formation of brown products of caramelisation in dessert wine is discussed.
Article
The roasting process induces structural changes in coffee galactomannans. To know more about the reaction pathways that occur during the roasting of coffee, mannosyl and galactomannosyl oligosaccharides, having a degree of polymerization (DP) between 3 and 4, were used as models for galactomannans. These compounds were dry-heated under air atmosphere from room temperature to 200 °C, being maintained at 200 °C for different periods of time. The roasted materials were analyzed by mass spectrometry (ESI-MS, MALDI-MS, and ESI-MSn) and methylation analysis. In the MS spectra were identified several [M+Na]+ ions belonging to a series from a single hexose to 10 hexose residues ([Hex1-10+Na]+). The ions corresponding to their respective mono- and tridehydrated derivatives ([Hex2-10-H2O+Na]+ and [Hex2-10-3H2O+Na]+, respectively) were also identified. ESI-MSn as well as deuterium-labeling and alditol derivatization experiments showed that the tridehydrations occur at the reducing end of the oligosaccharides. The identification of (1→2)- and (1→6)-linked mannose residues and (1→4)-linked glucose residues by methylation analysis allowed the conclusion that transglycosylation and isomerization reactions occur during dry thermal processing.
Article
LC-MS(n) and direct infusion-MS(n) have been applied for the first time to the characterisation of crude thearubigins isolated from black tea. The data generated have been used to test two hypotheses of thearubigin structure: (i) that a significant fraction of the thearubigins consist of polyhydroxylated derivatives of the better-known catechin dimers (theaflavins, theaflavin mono- and di-gallates, theacitrins) in redox equilibrium with their associated quinones; and (ii) that a significant fraction of the thearubigins consist of dicarboxylic acids generated by oxidative cleavage of aromatic diols. The data were consistent with the polyhydroxylation hypothesis and did not support the dicarboxylic acid hypothesis. Evidence is presented for the presence in crude thearubigins of at least 29 hydroxylated theaflavins (with between one and six oxygen insertions), at least 12 theaflavin mono-gallates (with between one and six oxygen insertions), at least nine theaflavin di-gallates (with between one and four oxygen insertions), and at least ten theacitrin mono-gallates (with between one and four oxygen insertions). Evidence is also presented for at least ten mono- or di-quinone forms of the parent compounds and hydroxylated derivatives in each of these homologous series. A general method for the analysis of complex mixtures by tandem LC-MS is furthermore introduced and established.
Article
This paper reports the development of a novel electrochemical assay for xanthohumol (XN) by square-wave adsorptive-stripping voltammetry (SWAdSV) with a hanging mercury drop electrode. The method showed good repeatability (CV < 2%) and linearity (between 10 and 250 μg L(-1)), as well as suitable limits of detection (2.6 μg L(-1)) and quantification (8.8 μg L(-1)). The method was applied for the quantification of this compound in spent hops, and the results obtained were compared with the HPLC-UV method. XN contents determined by the SWAdSV method were 16 ± 1 and 100 ± 4 μg L(-1) for aqueous and methanolic extracts, respectively. The developed new methodology considerably reduces the analysis time, approximately from 25 min (HPLC-UV method) to 7 min, enabling a high sample throughput. In addition, the detection and quantification limits were approximately 5-fold lower than those obtained with the chromatographic method.
Article
This review provides an overview of the current status of the chemistry and biology of di-d-fructose dianhydrides (DFAs) with a focus on their potential as functional foods. The history of this family of cyclic ketodisaccharides has expanded for almost 100 years and offers a paradigmatic example of artificial synthetic molecules that were identified as natural products later on and finally encountered in our own table. Issued from fundamental investigations on the reactivity of carbohydrates in strongly acidic media, DFAs remained laboratory curiosities for decades. Early reports on their isolation from plants raised doubts, until the formation of some DFA representatives by the action of microorganisms on fructans was reported in the middle 1980s. Since then, research on DFAs has run in parallel in the areas of microbiology and carbohydrate chemistry. Evidence of the potential of these compounds as functional food was accumulated from both sides, with the development of biotechnological processes for mass production of selected candidates and of chemical methodologies to prepare DFA-enriched products from sucrose or inulin. In 1994 a decisive discovery in the field took place in the laboratory of Jacques Defaye in Grenoble, France: the presence of DFAs in a commercial sucrose caramel was evidenced in a quite significant 18% mass proportion! The development of an efficient analytical protocol for DFAs and the stereoselective synthesis of individual standards allowed one to demonstrate that DFAs and their glycosylated derivatives (glycosyl-DFAs) are universally formed during caramelization reactions. They are not potential food products; they have actually always been in our daily food. Most important, they seem to exert beneficial effects: they are acariogenic, low-caloric, and promote the growth of beneficial microflora in the gut.
Article
High performance liquid chromatography (HPLC) on a calcium form cation exchange column with refractive index and photodiode array detection was used to investigate thermal decomposition as the cause of the loss of crystalline structure in sucrose. Crystalline sucrose structure was removed using a standard differential scanning calorimetry (SDSC) method (fast heating method) and a quasi-isothermal modulated differential scanning calorimetry (MDSC) method (slow heating method). In the fast heating method, initial decomposition components, glucose (0.365%) and 5-HMF (0.003%), were found in the sucrose sample coincident with the onset temperature of the first endothermic peak. In the slow heating method, glucose (0.411%) and 5-HMF (0.003%) were found in the sucrose sample coincident with the holding time (50 min) at which the reversing heat capacity began to increase. In both methods, even before the crystalline structure in sucrose was completely removed, unidentified thermal decomposition components were formed. These results prove not only that the loss of crystalline structure in sucrose is caused by thermal decomposition, but also that it is achieved via a time-temperature combination process. This knowledge is important for quality assurance purposes and for developing new sugar based food and pharmaceutical products. In addition, this research provides new insights into the caramelization process, showing that caramelization can occur under low temperature (significantly below the literature reported melting temperature), albeit longer time, conditions.
Article
Thearubigins are the most abundant group of phenolic pigments found in black tea, accounting for an estimated 60-70% of the solids in a typical black tea infusion. Fifty years ago the term thearubigins was first introduced and to date the chemical nature of the thearubigins remains largely unresolved, if not mysterious, despite numerous attempts made to clarify their structure. Thearubigins isolated from 15 commercial black teas have been analyzed using a strategy combining standard chemical characterization along with a series of modern complementary mass spectrometry techniques, including MALDI-TOF-MS, FTICR-MS, LC/TOF-MS and LC/MS/MS. Fifteen molecular formulas have been matched to constituents of fresh tea leaf that have survived processing and 21 to dimeric transformation products such as theasinensins, theaflavins, theaflavates, theanaphthoquinones, theacitrins and oolongtheanins, which were further confirmed by ESI MS/MS. MALDI-TOF-MS data revealed an average of 5000 additional thearubigin components in the mass range between m/z 1000 to 2100 clearly defining the molecular weight range of the thearubigin fraction. Six selected samples have for the first time been analyzed by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR-MS data revealed the presence of a maximum of 9428 peaks in the mass range 300 to 1000 m/z and molecular formulas were assigned to 1517 of them. Data interpretation strategies developed for petrolomics studies (van Krevelen and Kendrick analyses) have for the first time been applied to black tea thearubigins and a novel interpretation protocol has been developed to refine these procedures for the investigation of complex mixtures, leading to a novel hypothesis for the formation and structure of the black tea thearubigins named oxidative cascade hypothesis.
Article
Thearubigins are the most abundant group of phenolic pigments found in black tea accounting for an estimated 60% of the solids in a typical black tea infusion. Fifty years ago the term thearubigins was first introduced and up to now the chemical nature of the thearubigins remains largely unresolved if not mysterious despite many efforts clarifying their structure. This paper summarizes some of our attempts to clarify and elucidate the chemical nature of the thearubigins, presenting for 15 commercially representative teas data obtained using combustion analysis, IR spectroscopy, NMR spectroscopy, Diffusion NMR spectroscopy, UV-vis spectroscopy, Circular Dichroism spectroscopy and atomic force microscopy, MALDI-TOF-MS and ESI-FT-ICR-MS. The thearubigin fractions from these 15 teas are remarkably similar with respect to their spectroscopic fingerprint. The data obtained are consistent with the thearubigins being structures of not more than 2000Da with more than 5000 individual chemical entities detected that are susceptible to concentration-driven aggregation in aqueous solution, and that retain the chiral properties of the flavanols and theaflavins. By applying petrolomics-style data interpretation strategies and by developing novel data interpretation strategies a structural model for the thearubigins was developed.
Article
Caramelization commonly occurs when sugars, or products containing a high proportion of sugars, are heated either dry or in concentrated aqueous solutions, alone or in the presence of certain additives. Upon thermal treatment of sugars, dehydration and self-condensation reactions occur, giving rise to volatiles (principally 2-hydroxymethylfurfural, HMF), pigments (melanoidines) and oligosaccharidic material, among which di-D-fructose dianhydrides (DFAs) and glycosylated DFA derivatives of different degree of polymerization (DP) have been identified. This study reports a methodology to produce caramel-like products with a high content of DFAs and oligosaccharides thereof from commercial D-fructose based on the use of acid ion-exchange resins as caramelization promotors. The rate of formation of these compounds as a function of D-fructose concentration, catalyst proportion, temperature, catalyst nature and particle size has been investigated. The use of sulfonic acid resins allows conducting caramelization at remarkable low temperatures (70-90 degrees C) to reach conversions into DFA derivatives up to 70-80% in 1-2 h, with relative proportions of HMF < 2%.The relative abundance of individual DFA structures can be modulated by acting on the catalyst nature and reaction conditions, which offers a unique opportunity for nutritional studies of DFA-enriched products with well-defined compositions.
Article
Dynamic headspace gas chromatography, mass spectrometry, and sniffing port detection were used to analyze the volatile compounds of a Dutch commercial Capsicum cv. Mazurka at the ripening stages green, turning, and red. The samples were prepared by either cutting or blending of the fruits. The different bell pepper samples obtained had several odor compounds in common, i.e., 2,3-butanedione (caramel), 1-penten-3-one (chemical/pungent, spicy), hexanal (grassy), 3-carene (red bell pepper, rubbery), (Z)-beta-ocimene (rancid, sweaty), octanal (fruity), and 2-isobutyl-3-methoxypyrazine (green bell pepper). During bell pepper maturation the majority of volatile compounds, of which several had green-related odor notes, decreased or even disappeared. Only the levels of (E)-2-hexenoland (E)-2-hexenol, which have almond, fruity, sweet odors, were higher at the stages turning and red. Disruption of the cell structure favored lipid oxidation and the formation of related alcohols, aldehydes, and ketones.
Article
Soils, sediments, freshwaters, and marine waters contain natural organic matter (NOM), an exceedingly complex mixture of organic compounds that collectively exhibit a nearly continuous range of properties (size-reactivity continuum). NOM is composed mainly of carbon, hydrogen, and oxygen, with minor contributions from heteroatoms such as nitrogen, sulfur, and phosphorus. Suwannee River fulvic acid (SuwFA) is a fraction of NOM that is relatively depleted in heteroatoms. Ultrahigh resolution Fourier transform ion cyclotron (FTICR) mass spectra of SuwFA reveal several thousand molecular formulas, corresponding in turn to several hundred thousand distinct chemical environments of carbon even without accountancy of isomers. The mass difference deltam among adjoining C,H,O-molecules between and within clusters of nominal mass is inversely related to molecular dissimilarity: any decrease of deltam imposes an ever growing mandatory difference in molecular composition. Molecular formulas that are expected for likely biochemical precursor molecules are notably absent from these spectra, indicating that SuwFA is the product of diagenetic reactions that have altered the major components of biomass beyond the point of recognition. The degree of complexity of SuwFA can be brought into sharp focus through comparison with the theoretical limits of chemical complexity, as constrained and quantized by the fundamentals of chemical binding. The theoretical C,H,O-compositional space denotes the isomer-filtered complement of the entire, very vast space of molecular structures composed solely of carbon, hydrogen, and oxygen. The molecular formulas within SuwFA occupy a sizable proportion of the theoretical C,H,O-compositional space. A 100 percent coverage of the theoretically feasible C,H,O-compositional space by SuwFA molecules is attained throughout a sizable range of mass and H/C and O/C elemental ratios. The substantial differences between (and complementarity of) the SuwFA molecular formulas that are observed using six different modes of ionization (APCI, APPI, and ESI in positive and negative modus) imply considerable selectivity of the ionization process and suggest that the observed mass spectra represent simplified projections of still more complex mixtures.
Article
Thermal treatment of anhydrous, acidified sucrose or inulin yields caramels containing monosaccharides and oligomers, predominantly dianhydrides and higher oligomers derived by the addition of glycosyl residues to dianhydrides. Fourteen dianhydrides, most of which comprise two fructose moieties, have been identified by mass spectroscopy of the per-O-trimethylsilyl ethers. Thirteen of these dianhydrides have been isolated and characterized; five of the dianhydrides are novel compounds and one of these is a glucose-fructose dianhydride. The dianhydrides and related oligomers are thought to have a prebiotic effect by stimulating the proliferation of bifidobacteria in the large intestine.
Article
The monosaccharide (D-fructose, D-glucose, anhydrosugars), disaccharide (glucobioses) and pseudodisaccharide (di-D-fructose dianhydrides) content of D-fructose, D-glucose and sucrose caramels has been determined by gas-liquid chromatography-mass spectrometry (GLC-MS) of their trimethylsilyl (TMS) or TMS-oxime derivatives. The chromatographic profiles revealed significant differences in the disaccharide/pseudodisaccharide distribution depending on the caramel source: a D-fructose caramel contains prominent proportions of di-D-fructose dianhydrides, a D-glucose caramel mainly D-glucobioses, and a sucrose caramel similar proportions of both disaccharide/pseudodisaccharide series. It is noteworthy that di-D-fructose dianhydrides are found in all three types of caramels and might then be used as specific tracers of the authenticity of caramel, i.e., a product resulting from the controlled heat treatment of food-grade carbohydrates for use as food additives.
Article
Thermal treatments of solid mixtures of inulin and citric acid result in the formation of di-D-fructose dianhydrides and oligomers derived therefrom. The kinetics of formation of these compounds have been investigated and simulated in computer studies. A mechanism is proposed. The conditions used in this study were analogous to the conditions pertaining to the roasting of chicory, during which similar compounds are formed.
Article
Difructose anhydrides (DFAs) are the smallest cyclic disaccharides consisting of two fructose residues, and are expected to have novel physiological functions from their unique structures and properties. For mass-production of alpha-D-fructofuranose-beta-D-fructofuranose-2',1:2,3'-dianhydride (DFA III) and beta-D-fructofuranose-beta-D-fructofuranose-2',6:2,6'-dianhydride (DFA IV), Arthrobacter sp. H65-7 and A. nicotinovorans GS-9 were selected as the best producers of inulase II, which produced DFA III from inulin and LFTase, which produced DFA IV from levan. The enzymes were purified and their genes were subsequently cloned and expressed in E. coli at higher levels than in the original bacteria. Thus, it became possible to provide a large amount of DFA III and DFA IV for evaluating their physiological properties. DFA III and DFA IV have half the sweetness of sucrose, but cannot be digested by the digestive system of rats. Their use by the intestinal microorganisms was observed in vivo even though their assimilation could not be detected in vitro. This implied that they were degraded by an unknown system in the intestine. It was also found that they affected calcium absorption mainly in the small intestine through mechanisms different from the known stimulants such as fructooligosaccharides and raffinose.
Article
At currently achievable Fourier transform ion cyclotron resonance broadband mass spectrometry resolving power (m/deltam50% > 350,000 for 200 < m/z < 1,000), it would be necessary to spread out a conventional mass spectrum over approximately 200 m in order to provide visual resolution of the most closely resolved peaks. Fortunately, there are natural gaps in a typical mass spectrum, spaced 1 Da apart, because virtually no commonly encountered elemental compositions yield masses at those values. Thus, it is possible to break a broadband mass spectrum into 1-Da segments, rotate each segment by 90 degrees, scale each segment according to its mass defect (i.e., difference between exact and nominal mass), and then compress the spacing between the segments to yield a compact display. For hydrocarbon systems, conversion from IUPAC mass to "Kendrick" mass (i.e., multiplying each mass by 14.00000/14.01565) further simplifies the display by rectilinearizing the peak patterns. The resulting display preserves not only the "coarse" spacings (e.g., approximately 1 Da between odd and even masses, corresponding to either even vs odd number of nitrogens or 12C(c) vs 12C(c-1)13C1 elemental compositions of the same molecule; approximately 2-Da separations, corresponding to a double bond or ring; approximately 14 Da separations, corresponding to one CH2 group) but also the "fine structure" (i.e., different mass defects for different elemental compositions) across each 1-Da segment. The method is illustrated for experimental electrospray ionization FTICR ultrahigh-resolution mass spectra of a petroleum crude oil. Several thousand elemental compositions may be resolved visually in a single one-page two-dimensional display, and various compound families-class (NnOoSs), type (Z in C(c)H2(c+z)NnOoSs), and alkylation series-may be identified visually as well.
Article
The fragmentation behavior of 18 chlorogenic acids that are not substituted at position 1 has been investigated using LC-MS(4) applied to a methanolic coffee bean extract and commercial cider (hard cider). Using LC-MS(3), it is possible to discriminate between each of the three isomers of p-coumaroylquinic acid, caffeoylquinic acid, feruloylquinic acid, and dicaffeoylquinic acid, and a hierarchical key has been prepared to facilitate this process when standards are not available. MS(4) fragmentations further support these assignments, but were not essential in reaching them. The distinctive behavior of 4-acyl and 3-acyl chlorogenic acids compared with the 5-acyl chlorogenic acids is a key factor permitting these assignments. The fragmentation patterns are dependent upon the particular stereochemical relationships between the individual substituents on the quinic acid moiety. Fragmentation is facilitated by 1,2-acyl participation and proceeds through quinic acid conformers in which the relevant substituents transiently adopt a 1,3-syn-diaxial relationship. Selected ion monitoring at m/z 529 clearly indicated the presence in coffee of six caffeoylferuloylquinic acid isomers, whereas previously only two or three had been demonstrated. The hierarchical key permitted specific structures to be assigned to each of the six isomers. These assignments are internally consistent and consistent with the limited data previously available.
Article
All wrapped up: Carbon-encapsulated metal nanoparticles, carbon microspheres decorated with metal nanoparticles, and particles with layered structures are all accessible by means of a method based on hydrothermal treatment of glucose, which produces monodisperse colloidal carbon microspheres with reactive surfaces. The picture shows silver-cored carbon spheres obtained by using silver nanoparticles as seeds.
Article
Ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry has resolved and identified the elemental compositions of over 10000 organic constituents of coal and petroleum crude oil. A plot of Kendrick mass defect versus Kendrick nominal mass sorts compounds into homologous series according to compound class (i.e., numbers of N, O, and S heteroatoms), type (number of rings plus double bonds), and degree of alkylation (number of CH(2) groups), to yield unique elemental assignments from ultrahigh-resolution mass measurements in the 200-900 Da range. Interpretation of such a vast compilation requires a simple (preferably graphical) means to differentiate between complex organic mixtures of different origin or processing. In an extension of the recently revived van Krevelen plot, each elemental composition is projected onto two or three axes according to its H/C, O/C, and/or N/C atomic ratios. The H/C ratio separates compounds according to degree of saturation, whereas O/C or N/C ratios separate according to O and N classes. We show that the three-dimensional van Krevelen diagram can completely separate different classes in pyridine-extracted coal or petroleum samples and can also graphically distinguish fossil fuels according to their nature (coal vs petroleum), maturation (coals of different rank), and processing (the same coal at two stages of liquefaction). The van Krevelen diagram thus appears well suited to amplifying and exposing compositional differences within and between complex organic mixtures.
Article
Nine monosaccharides and four disaccharides were mass analyzed using a quadrupole time-of-flight tandem mass spectrometer combined with an electrospray ionization source. Product ion mass spectra of deprotonated, protonated, and sodiated saccharides were observed and were compared within each group of saccharides. Each of the deprotonated pentoses, hexoses and disaccharides yielded a significantly different product ion mass spectrum with the exception of alpha-lactose and beta-lactose. The disaccharides alpha- and beta-lactose differ only at the glycosidic linkage. Product ion mass spectra of protonated and sodiated alpha- and beta-lactose were indistinguishable also.
Article
High-sensitivity glycoprotein analyses are of particular interest in modern biomedical and clinical research, as well as in the development of recombinant protein products. The evolution of new hyphenated methodologies in high-sensitivity glycoprotein analysis is highlighted in this thematic review. These methodologies include, in particular, capillary LC/MALDI/TOF/TOF MS in conjunction with online permethylation platform, and silica-based lectin microcolumns interfaced to MS. The potential of these methodologies in glycomic and glycoproteomic analysis is demonstrated for model glycoproteins as well as total glycomes and glycoproteomes derived from biological samples. Additionally, the applications of CE-MS, CEC, and nanoLC with graphitized carbon in the areas of glycomics and glycoproteomics are described.
Article
Honey adulterations can be carried out by addition of inexpensive sugar syrups, such as high fructose corn syrup (HFCS) and inverted syrup (IS). Carbohydrate composition of 20 honey samples (16 nectar and 4 honeydew honeys) and 6 syrups has been studied by GC and GC-MS in order to detect differences between both sample groups. The presence of difructose anhydrides (DFAs) in these syrups is described for the first time in this paper; their proportions were dependent on the syrup type considered. As these compounds were not detected in any of the 20 honey samples analyzed, their presence in honey is proposed as a marker of adulteration. Detection of honey adulteration with HFCS and IS requires a previous enrichment step to remove major sugars (monosaccharides) and to preconcentrate DFAs. A new methodology based on yeast (Saccharomyces cerevisiae) treatment has been developed to allow the detection of DFAs in adulterated honeys in concentrations as low as 5% (w/w).
Article
The formation of furan and 2-methylfuran was studied in model systems based on sugars and selected amino acids. Both compounds were preferably formed under roasting conditions in closed systems yielding up to 330 micromol of furan and 260 micromol of 2-methylfuran per mol of precursor. The amounts obtained under pressure cooking conditions were much lower, usually below 20 micromol/mol, except for 2-furaldehyde, which yielded 70-100 micromol/mol of furan. Labeling studies indicated two major formation pathways for both furans: (i) from the intact sugar skeleton and (ii) by recombination of reactive C(2) and/or C(3) fragments. Under roasting conditions in the absence of amino acids, furan was mainly formed from the intact sugar skeleton. Formic and acetic acid were identified as byproducts of sugar degradation, indicating the split off of C(1) and/or C(2) units from hexoses. The presence of alanine, threonine, or serine promoted furan formation by the recombination of C(2) fragments, such as acetaldehyde and glycolaldehyde, which may originate from both sugars and amino acids. In aqueous solution, about half of furan was generated by the recombination of sugar fragments. 2-Methylfuran was preferably formed in the presence of amino acids by aldol-type reactions of C(2) and C(3) fragments with lactaldehyde as a key intermediate, the Strecker aldehyde of threonine. The total furan levels in cooked vegetables were increased by spiking with hexoses. However, in pumpkin puree, only about 20% of furan was formed from sugars, preferably from the intact carbon skeleton.
Article
This study aims to investigate the relationship between caramelization of several sugars including fructose, glucose, and sucrose and their glass transition temperature (Tg). Differential scanning calorimetry (DSC) was used for creating caramelized sugar samples as well as determining their glass transition temperature, which was found to decrease first and then increase as the holding time at the highest temperature increased. The extent of caramelization was quantified by UV-vis absorbance measurement and high-performance liquid chromatography analysis. Results showed that the amount of small molecules from the degradation of sugar increased very fast at the beginning of heating, and this increase slowed down in the later stage of caramelization. On the other hand, there was a lag phase in the formation of large molecules from the degradation of sugar at the beginning of heating, followed by a fast increase in the later stage of caramelization. The obtained results clearly indicate the impact of melting condition on the T g of sugars through formation of intermediates and end products of caramelization. Generally, when the heating condition is relatively mild, small molecules are formed first by decomposition of the sugar, which leads to a decrease of the overall Tg, and as the heating time becomes longer and/or the heating condition becomes more severe, polymerization takes over and more large molecules are formed, which results in an increase of the overall Tg. Mathematical modeling of the relationship will be presented as part II of the study in a separate paper.
Kinetics of formation of di-D-fructose dianhydrides during thermal treatment of insulin The oligosaccharide components of caramel Ruiz-Matute, A. I.; Soria, A. C.; Martínez-Castro, I.; Sanz, M. L. A new methodology based on GC-MS to detect honey adulteration with commercial syrups
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Profiling and characterization by LC-MS n of the chlorogenic acids and hydrox-ycinnamoylshikimate esters in maté paraguariensis) Investigation of thermal decomposition as the kinetic process that causes the loss of crystalline structure in sucrose using a chemical analysis approach (part II)
  • R Jaiswal
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  • K R Cadwallader
  • S J Schmidt
Jaiswal, R.; Sovdat, T.; Vivan, F.; Kuhnert, N. Profiling and characterization by LC-MS n of the chlorogenic acids and hydrox-ycinnamoylshikimate esters in maté paraguariensis). J. Agric. Food Chem. 2010, 58, 5471−5484. (27) Lee, J. W.; Thomas, L. C.; Jerrell, J.; Feng, H.; Cadwallader, K. R.; Schmidt, S. J. Investigation of thermal decomposition as the kinetic process that causes the loss of crystalline structure in sucrose using a chemical analysis approach (part II). J. Agric. Food Chem. 2011, 59 (2), 702−712.
  • Tomasik P.