Carbohydrate Mixtures Research Articles

Degradation of β‐carotene in amorphous polymer matrices. Effect of water sorption properties and physical state

The use of encapsulation in amorphous matrices of carbohydrate and/or polymer formed during dehydration processes to enhance the stability and retention of labile compounds is increasing in the food and pharmaceutical industries. Efforts to improve encapsulating properties have been made using mixtures of carbohydrates with proteins or gums in different proportions. The objective of the present work was to study the stability of encapsulated β-carotene and its degradation kinetics in maltodextrin/gum arabic and maltodextrin/gelatin matrices in relation to the physical properties and state of the dehydrated matrix. The degradation of β-carotene followed a first-order kinetic model of fractional retention for all encapsulating matrices. The Guggenheim-Anderson-de Boer (GAB) model was adequate to describe the sorption isotherms of the studied systems. β-Carotene losses were observed mainly at relative humidities (RHs) above the glass transition temperatures (T(g) ) of the corresponding systems, where the matrices were fully plasticised and collapsed (75 and 92% RH). At these high RHs the best β-carotene retention was obtained in the system containing gum arabic. The results showed that pigment degradation was determined by the physical state of the matrix, related to the degree of collapse. They represent a contribution to the knowledge of physical factors that affect the retention kinetics of labile biomolecules encapsulated in dehydrated matrices.

Biologically-Inspired Peptide Reagents for Enhancing IMS-MS Analysis of Carbohydrates

The binding properties of a peptidoglycan recognition protein are translated via combinatorial chemistry into short peptides. Non-adjacent histidine, tyrosine, and arginine residues in the protein's binding cleft that associate specifically with the glycan moiety of a peptidoglycan substrate are incorporated into linear sequences creating a library of 27 candidate tripeptide reagents (three possible residues permutated across three positions). Upon electrospraying the peptide library and carbohydrate mixtures, some noncovalent complexes are observed. The binding efficiencies of the peptides vary according to their amino acid composition as well as the disaccharide linkage and carbohydrate ring-type. In addition to providing a charge-carrier for the carbohydrate, peptide reagents can also be used to differentiate carbohydrate isomers by ion mobility spectrometry. The utility of these peptide reagents as a means of enhancing ion mobility analysis of carbohydrates is illustrated by examining four glucose-containing disaccharide isomers, including a pair that is not resolved by ion mobility alone. The specificity and stoichiometry of the peptide-carbohydrate complexes are also investigated. Trihistidine demonstrates both suitable binding efficiency and successful resolution of disaccharides isomers, suggesting it may be a useful reagent in IMS analyses of carbohydrates.

Post-exercise Protein And Carbohydrate Ingestion Enhances Exercise-induced Increase In Plasma Volume And Albumin Content

The exercise-induced plasma volume (PV) expansion is observed after a bout of high-intensity exercise which has been suggested to rely on a rapid increase in plasma albumin content (Albcont). We recently reported that the increase in Albcont and PV from the 1st to 23rd hour after a bout of high-intensity exercise was enhanced by a mixture of protein and carbohydrate (CHO) intake immediately after exercise compared with non-protein and low-calorie placebo intake. It has remained unclear, however, which is a key condition to enhance the increase in Albcont and PV; the timing of protein and CHO intake after exercise or the total amount of daily protein and energy intake. PURPOSE: To test the hypothesis that the increase in Albcont and PV after a bout of high-intensity exercise is enhanced when a mixture of protein and CHO was taken immediately after exercise compared with 2 hours later. METHODS: Seven young men (∼23 yrs) completed two trials those of which differ in the timing of intake (immediately after exercise, 0H; and 2 hours later, 2H) of a mixture of protein and CHO (3.2 kcal and 0.18 g protein per kg body weight) after exercise under a controlled food intake to the age-matched RDA. The subjects performed a bout of 72-min intense and intermittent exercise (8 sets of 4 min at 80% VO2max intermittent by 5 min at 20% VO2max) by using an upright cycling ergometer. PV, plasma albumin concentration ([Alb]p), and Albcont (PV × [Alb]p) were determined before exercise, at the end of exercise, every hour from the 1st to the 5th hour and at the 23rd hour after exercise during subjects were resting in a seating position. RESULTS: In 0H trial, Albcont and PV increased minimally by 1.2% and -1.2% at the 5th hour and by 1.6% and 2.1% at the 23rd hour, respectively, from before exercise on average for 7 subjects. On the other hand, in 2H trial, Albcont and PV increased prominently by 3.0% and 1.1% at the 5th hour and by 4.6% and 5.0% at the 23rd hour, respectively. The increase in Albcont and PV at the 5th and 23rd hour was significantly higher in 2H trial than in 0H trial. CONCLUSIONS: The mixture of protein and CHO intake immediately after exercise enhanced the increase in Albcont and PV after a bout of high-intensity exercise compared with 2 hours later. Thus, the timing of protein and CHO intake after exercise is a key condition to enhance the increase in Albcont and PV.

Numerical modelling and characterization of nanofiltration membranes for the separation of carbohydrate mixtures

AbstractThe results of an experimental and computational investigation of the selective separation of carbohydrates on nano‐membranes in cross‐flow filtration are reported. Two commercial membranes (NF270‐400 and TFC‐SR3) were characterised in terms of permeability and rejection of carbohydrate solutions. It is shown that the membranes can be used to recover glucose and galactose from their mixtures with lactose. The permeate flux is shown to depend on sugar concentration, with permeate flux decreasing as the concentration increases. Quantitative evaluation using numerical analysis of the above flow and separation process showed that the performance of nano‐membranes can be captured and reproduced with sufficient accuracy, thereby reducing the number of experiments require to evaluate the suitability of membranes in different applications. A Fickian approach is adopted to model the separation, and is shown to be effective.

Alkaline subcritical water gasification of dairy industry waste (Whey)

The near-critical water gasification of dairy industry waste in the form of Whey, a product composed of mixtures of carbohydrates (mainly lactose) and amino acids such as glycine and glutamic acid, has been studied. The gasification process involved partial oxidation with hydrogen peroxide in the presence of NaOH. The reactions were studied over the temperature range from 300 °C to 390 °C, corresponding pressures of 9.5–24.5 MPa and reaction times from 0 min to 120 min. Hydrogen production was affected by the presence of NaOH, the concentration of H 2O 2, temperature, reaction time and feed concentration. Up to 40% of the theoretical hydrogen gas production was achieved at 390 °C. Over 80% of the Whey nitrogen content was found as ammonia, mainly in the liquid effluent.

Hydrothermal formose reaction

The self-condensation of formaldehyde is a one pot reaction resulting in a complex mixture of carbohydrates. Based on a simple chemical, the reaction was previously considered as a prebiotic source for sugar generation. Usually, a high pH and the presence of catalytically active species are required. Here, the formose reaction was performed under hydrothermal temperatures up to 200 °C, and carbohydrates were obtained under even simpler conditions. We found no pronounced catalytic influence of active cations, and a slightly alkaline pH was sufficient to induce the reaction. Maximum yield was reached in very short times, partly less than 1 minute. No selectivity for a particular carbohydrate, although searched for, was found. Contrary to reactions performed at lower temperatures, hexoses were only formed in negligible yields, whereas the shorter carbohydrates accounted for the major fraction. Among the pentoses, ribose and the ketoses with corresponding stereochemistry were formed in higher yields compared to the reaction at lower temperature. Furthermore, we identified 2-deoxyribose in the product mix and found strong indications for the presence of other deoxy compounds. Hence, the hydrothermal formose reaction shows some remarkable differences compared to the conventional reaction at moderate temperatures.

Acetylation of corn distillers dried grains

This paper shows that acidic conditions provide substantially higher % acetyl content, intrinsic viscosity and thermoplasticity even at low ratios of acetic anhydride and catalyst concentrations compared to using alkaline conditions for acetylation of oil-and-zein-free distillers dried grains with solubles (DDGS). Conventional methods of carbohydrate and protein acetylation are unsuitable for acetylating DDGS which is a mixture of carbohydrates and proteins. In this research, methods were developed to simultaneously acetylate the carbohydrates and proteins in DDGS using alkaline and acidic catalyses. The effect of various acetylation conditions on the % acetyl content and intrinsic viscosity of DDGS acetates was studied. Acetylation of DDGS was confirmed using FTIR and 1H NMR and thermal behavior of the DDGS acetates was studied using TGA and DSC. The highest % acetyl content obtained was 28.1% (Degree of substitution (DS) of 1.5) under alkaline conditions using an anhydride to DDGS ratio of 3:1 whereas a much higher % acetyl content of 36.1% (DS 2.1) was obtained under acidic conditions even with a lower anhydride to DDGS ratio of 2:1. DDGS acetates obtained using alkaline catalysts also had higher melting temperature and low melting enthalpy and hence exhibit poor thermoplasticity compared to the DDGS acetates obtained using acid catalysts.

Thermoplastics from acetylated zein-and-oil-free corn distillers dried grains with solubles

This paper reports the development of green thermoplastics from corn distillers dried grains with solubles (DDGS) using a novel method of simultaneous acetylation of the carbohydrates and proteins in oil-and-zein-free DDGS. DDGS is an inexpensive and abundant co-product of ethanol production with limited industrial applications. However, DDGS is a mixture of carbohydrates and proteins and current methods of acetylating carbohydrates and proteins are not suitable for acetylating DDGS with high efficiency and low cost. In this research, acetylated DDGS were characterized for % acetyl content, degree of hydrolysis and thermal behavior. Acetylation resulted in products soluble and insoluble in acetic acid. The soluble product had high % acetyl content (44.9%) similar to that of commercial cellulose triacetate (44.8%, or a degree of substitution of (3.0)). Both the soluble and total (soluble and insoluble) products were compression molded to form thermoplastic bioproducts.

Bioanalytical Methods for Food Contaminant Analysis

Foods are complex mixtures of lipids, carbohydrates, proteins, vitamins, organic compounds, and other naturally occurring substances. Sometimes added to this mixture are residues of pesticides, veterinary and human drugs, microbial toxins, preservatives, contaminants from food processing and packaging, and other residues. This milieu of compounds can pose difficulties in the analysis of food contaminants. There is an expanding need for rapid and cost-effective residue methods for difficult food matrixes to safeguard our food supply. Bioanalytical methods are established for many food contaminants such as mycotoxins and are the method of choice for many food allergens. Bioanalytical methods are often more cost-effective and sensitive than instrumental procedures. Recent developments in bioanalytical methods may provide more applications for their use in food analysis.

The Effect of a Low Carbohydrate Beverage with Added Protein on Cycling Endurance Performance in Trained Athletes

Ingesting carbohydrate plus protein during prolonged variable intensity exercise has demonstrated improved aerobic endurance performance beyond that of a carbohydrate supplement alone. The purpose of the present study was to determine if a supplement containing a mixture of different carbohydrates (glucose, maltodextrin, and fructose) and a moderate amount of protein given during endurance exercise would increase time to exhaustion (TTE), despite containing 50% less total carbohydrate than a carbohydrate-only supplement. We also sought post priori to determine if there was a difference in effect based on percentage of ventilatory threshold (VT) at which the subjects cycled to exhaustion. Fifteen trained male and female cyclists exercised on 2 separate occasions at intensities alternating between 45 and 70% VO2max for 3 hours, after which the workload increased to ∼74-85% VO2max until exhaustion. Supplements (275 mL) were provided every 20 minutes during exercise, and these consisted of a 3% carbohydrate/1.2% protein supplement (MCP) and a 6% carbohydrate supplement (CHO). For the combined group (n = 15), TTE in MCP did not differ from CHO (31.06 ± 5.76 vs. 26.03 ± 4.27 minutes, respectively, p = 0.064). However, for subjects cycling at or below VT (n = 8), TTE in MCP was significantly greater than for CHO (45.64 ± 7.38 vs. 35.47 ± 5.94 minutes, respectively, p = 0.006). There were no significant differences in TTE for the above VT group (n = 7). Our results suggest that, compared to a traditional 6% CHO supplement, a mixture of carbohydrates plus a moderate amount of protein can improve aerobic endurance at exercise intensities near the VT, despite containing lower total carbohydrate and caloric content.

Amino acids in nectar enhance longevity of female Culex quinquefasciatus mosquitoes

Culex mosquitoes feed on a wide range of nectars consisting of mostly carbohydrates and amino acids, however, little is known about the utilization and effects of these different carbohydrates and their accompanying amino acids on longevity. Culex quinquefasciatus larvae were reared on low- and high-quantity food diets to produce adults that were nutritionally representative of wild-caught and laboratory-reared mosquitoes. Emerging adults reared on low- or high-quantity food diets as larvae were then provided Lantana camara nectar mimics containing mixtures of carbohydrates and amino acids to evaluate effects of nectar amino acids on longevity. Carbohydrates (with or without amino acids) were a critical component of the adult diet, and in their absence, adult mosquitoes died within 3–5 days. The nectar mimic that contained both carbohydrates and amino acids did not increase adult longevity of males originating from either poorly or well-fed larvae. However, females receiving adult diets containing both carbohydrates and amino acids lived 5% longer than females fed adult diets with only sugar.

Sex-specific differences in nutrient regulation in a capital breeding caterpillar, Spodoptera litura (Fabricius)

Nutrient requirements by male and female insects are likely to differ, but relatively little is known regarding how sexes differ in their regulation of macronutrient acquisition. The present study reports the results from a laboratory experiment in which behavioural and physiological components of nutrient regulation were compared between male and female caterpillars of Spodoptera litura (Fabricius). When provided with choices between two nutritionally complementary foods (one is a protein-biased diet and the other a carbohydrate-biased diet), both males and females adjusted their food selection to defend an intake target. However, the composition of diet preferred by the two differed, with females selecting significantly more protein than males with no difference in carbohydrate intake between the two. When confined to single diets with varying mixtures of protein and carbohydrate [P:C ratios, expressed as the percentage of diet by dry mass: protein 42%:carbohydrate 0% (p42:c0), p35:c7, p28:c14, p21:c21, p14:c28, p7:c35], females consumed more macronutrients than did males across on all P:C diets except the extremely carbohydrate-biased diet (p7:c35). Under both choice and no-choice feeding condition, such sex differences in nutrient intake were not expressed until late in the feeding stage of the final stadium. Sexes also differed in post-ingestive utilization of ingested nutrients. Females utilized ingested protein for body growth with greater efficiency compared to males, presumably reflecting provisioning their adult needs for protein to develop eggs, whereas males were more efficient at depositing lipids from carbohydrate intake than females.

Oligosaccharide-Induced Whey-Specific CD25+ Regulatory T-Cells Are Involved in the Suppression of Cow Milk Allergy in Mice

Dietary intervention with a unique prebiotic nondigestible carbohydrate mixture has been shown to reduce the development of allergic disease in infants at risk. In this study, the involvement of CD25+ regulatory T-cells (Treg) in the carbohydrate-induced effects was investigated in mice orally sensitized with whey using adoptive transfer experiments. Donor mice were sensitized with whey and fed a diet containing short-chain galacto-, long-chain fructo- and acidic-oligosaccharides, or a control diet starting 2 wk before sensitization. The acute allergic skin reaction upon intradermal whey challenge was determined and whey-specific Ig were measured. Splenocytes of the donor mice were transferred to naïve recipient mice after partial ex vivo depletion of CD25+ Treg. The prebiotic diet clearly diminished the acute allergic skin reaction (P < 0.001). Whey-sensitized recipient mice transferred with splenocytes from whey-sensitized, prebiotic-fed donor mice displayed almost complete prevention of the acute allergic skin reaction compared with mice receiving cells from sham-sensitized, prebiotic-fed donor mice (P < 0.001). Partial depletion of CD25+ T-cells inhibited these effects (P < 0.001), although IgE sensitization was not prevented. This study indicates the involvement of whey-specific CD25+ Treg in the suppression of the allergic effector response induced by dietary intervention with prebiotics.

Supercritical fluid purification of complex carbohydrate mixtures produced by enzimatic transglycosilation and isomerized with complexating reagents

Food-grade complex oligosaccharide mixtures manufactured commercially via transglycosylase reactions using disaccharides, such as sucrose or lactose as the raw material, are, in general, not pure products. Reducing oligosaccharides may be isomerized using borates and aluminates as complexating agents to obtain prebiotic oligosaccharides. Complexating agents are used to avoid side-reactions but are difficult to remove from mixture. In the present work, a new process based on the extraction with supercritical CO 2 plus a co-solvent has been developed to purify reaction mixtures leading to pure prebiotic oligosaccharides. A three-step supercritical extraction process has been designed to purify carbohydrates according to its degree of polymerization; the appropriate selection of the co-solvent employed, together with the most suitable extraction conditions allowed the almost complete removal of monosaccharides, and disaccharides from the mixture, leading to pure oligosaccharides as a residue of the extraction process. In this process, not only complete fractionation of mono-, di- and trisaccharides was achieved but also elimination of borates and aluminates from the prebiotic carbohydrates mixture.

Biofuel production in Escherichia coli: the role of metabolic engineering and synthetic biology

The microbial production of biofuels is a promising avenue for the development of viable processes for the generation of fuels from sustainable resources. In order to become cost and energy effective, these processes must utilize organisms that can be optimized to efficiently produce candidate fuels from a variety of feedstocks. Escherichia coli has become a promising host organism for the microbial production of biofuels in part due to the ease at which this organism can be manipulated. Advancements in metabolic engineering and synthetic biology have led to the ability to efficiently engineer E. coli as a biocatalyst for the production of a wide variety of potential biofuels from several biomass constituents. This review focuses on recent efforts devoted to engineering E. coli for the production of biofuels, with emphasis on the key aspects of both the utilization of a variety of substrates as well as the synthesis of several promising biofuels. Strategies for the efficient utilization of carbohydrates, carbohydrate mixtures, and noncarbohydrate carbon sources will be discussed along with engineering efforts for the exploitation of both fermentative and nonfermentative pathways for the production of candidate biofuels such as alcohols and higher carbon biofuels derived from fatty acid and isoprenoid pathways. Continued advancements in metabolic engineering and synthetic biology will help improve not only the titers, yields, and productivities of biofuels discussed herein, but also increase the potential range of compounds that can be produced.

Chromatographic analysis of major non-structural carbohydrates in several wood species – an analytical approach for higher accuracy of data

The exact and reliable determination of non-structural carbohydrates (NSC) in wood samples of different origin allows to gain further insight into the biogeochemical carbon cycle, i.e. processes that determine how carbon – and carbon dioxide – migrate between the land, the sea and the atmosphere. Plants are an essential part of this cycle using carbon dioxide in photosynthesis and locking up carbon within proteins and carbohydrates. Analytical determination of NSC is complicated by the complexity of the carbohydrate mixtures. However, most of them are present at the trace level only, and do not substantially contribute to the global NSC. Most important are glucose, sucrose, fructose and starch. Traditionally, these carbohydrates are analyzed spectrophotometrically. The spectrophotometric method does not provide any information on concentrations of sugar alcohols and raffinose. They can make up to a quarter of total NSC in deciduous tree samples. Consequently, ignoring them will severely impair the accuracy of NSC data in these samples. We will therefore present a method that allows the reliable determination of the following sugar alcohols and carbohydrates: inositol, sorbitol, mannitol, glucose, fructose, sucrose, raffinose and starch. These were the major contributors to the pool of non-structural carbohydrates in the samples we examined. It is important to note, that the portion of sugar alcohols and raffinose in the samples ranged from <2–25% of total NSC, irrespective of the plant species, with strongest impact (≥15% of NSC) for the conifer species “Pine” and the deciduous species “Ash Tree” and “Wild Cherry”. Application of our method substantially improved the accuracy of NSC data in these samples if compared to those of the spectrophotometrical analysis.

Study on Industrial Scale Chromatographic Separation Methods of Galactose from Biomass Hydrolysates

AbstractGalactose is an aldohexose, which has commercial uses in the pharmaceutical and food industries. Since monomeric galactose is not a freely occurring compound, it must be produced from galactose‐containing hydrolysates. This paper reports the results of experimental studies of the chromatographic separation of galactose in aqueous solutions by ion exchange resins on an industrial scale. Until now, galactose has only been determined from various solutions by liquid chromatography (HPLC) on an analytical scale. Chromatographic separation of galactose from carbohydrate mixtures was studied with strong acid cation exchange resins in Na+, Ca2+ forms and strong base anion exchange resin in SO42– form. The feed solutions were hydrolysates from three possible galactose sources: lactose, gum arabic and hemicellulose in spent sulfite liquor. The main monosaccharide impurities in these raw materials were glucose, arabinose, and xylose. It was demonstrated that large scale liquid chromatography can be used effectively for galactose separation from complex carbohydrate mixtures such as plant hydrolysates as well as lactose hydrolysate.

Analysis of Mixture of Maltooligoses Using MALDI-TOFMS: Influence of Cationizing Agent Types

reported that the ion abundances of carbohy-present work, we analyzed maltooligosaccharides using MALDI and the sample was prepared with a cationizing agent to enhance the ionization efficiency. Nine alkali metal salts were employed as the cationizing agents and the differences in the ionization efficiencies, depending on the cationizing agents, were com-pared.We prepared the sample by mixing 1 aliquot of the 5 mM carbohydrate mixture solution with 5 aliquots of the 100 mM matrix solution, which yields an analyte to matrix ratio of 1:100. Concentrations of the alkali metal salts were 1 mM. Figure 1 shows MALDI-TOF mass spectra of the samples containing LiTFA, NaTFA, and KTFA as the cationizing agent, respec-tively. The [M + cation]

Carbohydrate−Protein Interactions Investigated on Plastic Chips Statically Coated with Hydrophobically Modified Hydroxyethylcellulose

We developed a novel method for rapid screening of carbohydrate-protein interactions using poly(methyl methacrylate) (PMMA) channels statically coated with hydrophobically modified hydroxyethylcellulose (HM-HEC). We found that a self-assembled monolayer (SAM) of HM-HEC on a PMMA surface intact by water allows rapid and reproducible separations of glycan samples using a 20 mM phosphate without HM-HEC. The underlying mechanism for dynamic and static coatings on the PMMA surface is discussed. Simultaneous analysis of the molecular interaction between a complex mixture of carbohydrates from alpha1-acid glycoprotein and proteins has been successfully achieved in PMMA channels statically coated with a SAM of HM-HEC.

Structure of the Polyphenolic Component of Suberin Isolated from Potato (Solanum tuberosum var. Nikola)

Suberin is present in the underground parts of vegetables and in the bark of trees. Characterization of suberin and the structure of its polyphenolic component have been hampered by insolubility of the polymers. Thus, enzymatically isolated and extractive free suberin enriched fraction from potato, Solanum tuberosum var. Nikola, and the chemically further fractionated phenolics were characterized in solid state by FTIR, DSC, and elemental analysis to identify the groups and to verify success of isolation. For MW and quantitative determination of the groups, polymers were solubilized in ionic liquid derivatized and analyzed by GPC and (31)P NMR. Suberin enriched fraction, MW = ca. 44 x 10(3) g/mol, is a mixture of carbohydrates and polyesters of aliphatic long chain hydroxy fatty acids and diacids linked via ester bonds to the phenolics, MW = ca. 27 x 10(3) g/mol, formed by guaiacyl- and p-hydroxyphenyl structures. Phenolics in peels may be important sources of antioxidants for various applications.