Fructose-glucose Mixtures Research Articles

The Importance of Carbohydrate Intake for Maintaining Glycogen Stores and Physical Performance during Prolonged Exercise : A Literature Review

The study investigates the critical role of carbohydrate intake in maintaining glycogen stores and enhancing physical performance during prolonged exercise. The primary aim is to evaluate how carbohydrate consumption influences glycogen levels and athletic performance, focusing on intake types and timing. Utilizing a qualitative descriptive research model, the study conducts an extensive literature review, involving a thorough search of scientific databases such as Scopus, ScienceDirect, and Google Scholar. Specific keywords like "Carbohydrates," "Glycogen Stores," and "Prolonged Exercise" guide the search for relevant articles. These articles are analyzed to extract and synthesize information on the relationship between carbohydrate intake and glycogen reserves during extended physical activities. The findings highlight that a daily carbohydrate intake of 6-12 g/kg body weight is essential for optimal glycogen levels and performance. Simple carbohydrates and fructose-glucose mixtures are particularly effective in enhancing recovery. Additionally, carbohydrate loading before intense exercise significantly improves glycogen stores and endurance performance. The study concludes that while adequate carbohydrate intake is vital for sustaining performance and facilitating recovery, further research is needed to explore the long-term effects and individual variations in carbohydrate nutrition strategies. This includes examining diverse exercise types, athlete profiles, and the interplay between carbohydrates and other dietary components

Efficient continuous dehydration of fructose to 5-hydroxymethylfurfural in ternary solvent system

Biomass-derived 5-hydroxymethylfurfural (HMF) has been identified as a versatile precursor for clean fuels and degradable polymers. Here, we developed an efficient flow-through system to continuously produce HMF in high selectivity from fructose dehydration. Effects of solvent, the relative ratio of aqueous to organic phase, the proportion of different cosolvents in the organic phase as well as the reaction variables on reactivity of fructose dehydration to HMF were comprehensively investigated to obtain the optimal results. The conduction of a H2O/dioxane/methyl isobutyl ketone (MIBK) ternary solvent system in combination with Amberlyst 70 as catalyst contributed to 93 % selectivity and 84 % yield of HMF in residence time as short as 1.6 min. The strengthened hydrogen bonding interactions by the addition of dioxane accounted for an increase in the interactions of fructose with water and cosolvent molecules, accelerating the dehydration rate. Meanwhile, the in-situ extraction of HMF from active aqueous phase to organic phase by MIBK protected it from unfavorable side reactions. The reaction system exhibited good stability without significant change on the catalytic performance over 10 h reaction. Additionally, fructose was selectively dehydrated from fructose-glucose mixtures, holding great promises for the integration with the industrial operations producing mixture of sugars (such as fructose corn syrup).

Selective fructose dehydration to 5-hydroxymethylfurfural from a fructose-glucose mixture over a sulfuric acid catalyst in a biphasic system: Experimental study and kinetic modelling

A two-step process combining the (equilibrium) glucose isomerization to fructose with selective dehydration of fructose in the obtained sugar mixture to 5-hydroxymethylfurfural (HMF), where glucose is largely unconverted and recycled, represents an attractive concept to increase the overall efficiency for HMF synthesis. This work presents experimental and modelling studies on the conversion of such fructose-glucose mixture to HMF using the sulfuric acid catalyst in a water-methyl isobutyl ketone biphasic system under a wide range of conditions (e.g., temperature, catalyst and sugar concentrations). Through detailed product analyses and ESI-MS spectroscopy, the excess formation of formic acid (together with humins) by the direct sugar/HMF degradation was confirmed and included in the reaction network (neglected in most literatures). The kinetic modelling based on batch experiments in monophasic water well describes the measurements thereof, whereas distinct deviations were found in the prediction of typical literature kinetic models. The incorporation of HMF equilibrium extraction into the developed kinetic model, with consideration of phase volume change as a function of temperature and partial phase miscibility, enables to predict reaction results in the biphasic system in batch. This kinetic model allows to optimize conditions for HMF synthesis that are favored in continuous reactors with minimized back mixing. Based on the model implications, the biphasic system was optimized with slug flow microreactors to better address process intensification and scale-up aspects. Using a simulated fructose-glucose mixture feedstock to represent commercially available high fructose corn syrups, a maximum HMF yield of 81% was obtained at 155 °C over 0.05 M H2SO4 at a residence time of 16 min in the microreactor, with 96% fructose conversion and over 95% of glucose remaining unconverted.

Fructose-containing caloric sweeteners as a cause of obesity and metabolic disorders.

Compared with other carbohydrates, fructose-containing caloric sweeteners (sucrose, high-fructose corn syrup, pure fructose and fructose-glucose mixtures) are characterized by: a sweet taste generally associated with a positive hedonic tone; specific intestinal fructose transporters, i.e. GLUT5; a two-step fructose metabolism, consisting of the conversion of fructose carbones into ubiquitous energy substrates in splanchnic organs where fructolytic enzymes are expressed, and secondary delivery of these substrates to extrasplanchnic tissues. Fructose is a dispensable nutrient, yet its energy can be stored very efficiently owing to a rapid induction of intestinal fructose transporters and of splanchnic fructolytic and lipogenic enzymes by dietary fructose-containing caloric sweeteners. In addition, compared with fat or other dietary carbohydrates, fructose may be favored as an energy store because it uses different intestinal absorption mechanisms and different inter-organ trafficking pathways. These specific features make fructose an advantageous energy substrate in wild animals, mainly when consumed before periods of scarcity or high energy turnover such as migrations. These properties of fructose storage are also advantageous to humans who are involved in strenuous sport activities. In subjects with low physical activity, however, these same features of fructose metabolism may have the harmful effect of favoring energy overconsumption. Furthermore, a continuous exposure to high fructose intake associated with a low energy turnover leads to a chronic overproduction of intrahepatic trioses-phosphate production, which is secondarily responsible for the development of hepatic insulin resistance, intrahepatic fat accumulation, and increased blood triglyceride concentrations. In the long term, these effects may contribute to the development of metabolic and cardiovascular diseases.

Solving a dynamic separation problem using MINLP techniques

In the present paper a dynamic separation problem is modeled and solved using Mixed Integer Nonlinear Programming (MINLP) techniques. The objective is to maximize the profit for continuous cyclic operation, and at the same time, to find the optimal configuration for the separation column system. The dynamics of the chromatographic separation process are modeled as a boundary value problem which is solved, within the optimization, using an iterative finite difference method. The separation of a fructose-glucose mixture is solved using the Extended Cutting Plane (ECP) method. It is shown that the production planning can be done efficiently for different purity requirements, such that all the output of a system can be utilized. Using a process design that is optimized it is thus possible to use existing complex systems, or to design new systems, more efficiently and also to reduce the energy costs or the costs in general. The presented problem is a challenging application involving time-consuming calculations that, though the high capacity of todays computers, underlines the role of robust and fast numerical tools within optimization.

Fructose Intake at Current Levels in the United States May Cause Gastrointestinal Distress in Normal Adults

Objective Fructose intake has increased considerably in the United States, primarily as a result of increased consumption of high-fructose corn syrup, fruits and juices, and crystalline fructose. The purpose was to determine how often fructose, in amounts commonly consumed, would result in malabsorption and/or symptoms in healthy persons. Design Fructose absorption was measured using 3-hour breath hydrogen tests and symptom scores were used to rate subjective responses for gas, borborygmus, abdominal pain, and loose stools. Subjects/Setting The study included 15 normal, free-living volunteers from a medical center community and was performed in a gastrointestinal specialty clinic. Intervention Subjects consumed 25- and 50-g doses of crystalline fructose with water after an overnight fast on separate test days. Main Outcome Measures Mean peak breath hydrogen, time of peak, area under the curve (AUC) for breath hydrogen and gastrointestinal symptoms were measured during a 3-hour period after subjects consumed both 25- and 50-g doses of fructose. Statistical Analyses Differences in mean breath hydrogen, AUC, and symptom scores between doses were analyzed using paired t tests. Correlations among peak breath hydrogen, AUC, and symptoms were also evaluated. Results More than half of the 15 adults tested showed evidence of fructose malabsorption after 25 g fructose and greater than two thirds showed malabsorption after 50 g fructose. AUC, representing overall breath hydrogen response, was significantly greater after the 50-g dose. Overall symptom scores were significantly greater than baseline after each dose, but scores were only marginally greater after 50 g than 25 g. Peak hydrogen levels and AUC were highly correlated, but neither was significantly related to symptoms. Conclusions Fructose, in amounts commonly consumed, may result in mild gastrointestinal distress in normal people. Additional study is warranted to evaluate the response to fructose-glucose mixtures (as in high-fructose corn syrup) and fructose taken with food in both normal people and those with gastrointestinal dysfunction. Because breath hydrogen peaks occurred at 90 to 114 minutes and were highly correlated with 180-minute breath hydrogen AUC, the use of peak hydrogen measures may be considered to shorten the duration of the exam.

Inverse association between the effect of carbohydrates on blood glucose and subsequent short-term food intake in young men , ,

A primary mechanism by which carbohydrates are thought to regulate satiety and food intake is through their effect on blood glucose. The objectives were to describe the effect of defined carbohydrate preloads on food intake and blood glucose and to determine the association between food intake and blood glucose. Three experiments were conducted in which selected carbohydrates as 1255-kJ isovolumetric beverages were administered to young men after an overnight fast. Measurements of blood glucose and appetite were made at specified times during the next 60 min. Food intake was measured at 60 min. Glucose resulted in the highest glycemic response, which was followed, in order, by the responses to polycose, sucrose, amylopectin, a fructose-glucose mixture, and amylose. The high-glycemic-index preloads (glucose, polycose, and sucrose) resulted in lower mealtime energy intake during a test meal at 1 h, but the low-glycemic-index preloads (amylose, amylopectin, and a fructose-glucose mixture) did not. An inverse relation was observed between the blood glucose concentrations in the area under the curve and the subjective appetite (r = -0.23, P < 0.05) and food intake at 60 min (r = -0.24, P < 0.05). Food intake and subjective appetite are inversely associated with blood glucose response in the 60 min after consumption of carbohydrates. Carbohydrates with a high glycemic index (glucose, polycose, and sucrose) suppress subjective appetite and food intake in the short term, but those with a low glycemic index (amylose and amylopectin) do not.

Glass-softening of trehalose and calorimetric transformations in its liquid state

To gain insight into the molecular relaxation processes and interaction of water with trehalose (α-d-Glucopyranosyl-α-d-glucopyranoside), changes in the state of trehalose dihydrate with temperature, water content and thermal treatment at ambient and vacuum conditions have been investigated by differential scanning calorimetry, systematically over a broad temperature range from 313 to 523K. Also, structural relaxation and temperature range of glass-softening of its partially dehydrated and completely dehydrated liquid state have been investigated and analysed in terms of the non-exponential, non-linear manner of structural relaxation. The heat released on the removal of water from trehalose dihydrate is 13.8kJmol−1, which is ∼66% of that expected from evaporation of water alone. The difference is attributed partly to the exothermic processes of dissolution of trehalose in the water released on heating before evaporation and partly to conformer transformation. The onset temperature of water release increased by ∼10K when the sample had been partially dried in vacuum. The glass-softening temperature, Tg, of the apparently dry trehalose was found to be in the range 386–402K. It increased when the molten trehalose was thermally cycled between 413 and 467K, as it did when it was heated to temperatures above 513K, where the trehalose partially decomposed. In addition to the glass-softening endotherm, the trehalose showed several endothermic features in the liquid state, whose magnitude varied with the thermal treatment. Amongst these, the most prominent feature appeared in the 440K range. The endotherms observed on heating liquid trehalose were attributed to the kinetic unfreezing of the tautomeric forms and various other conformers of the trehalose molecule and the effects of H-bonding between them. Their concentration changed on annealing the liquid, which in turn changed the viscosity. Thus Tg of trehalose depended upon the thermal history of the melt. The endothermic features in liquid trehalose appeared similar to those already observed in liquid fructose, galactose and fructose–glucose mixture. Structural relaxation of trehalose was found to be as non-exponential as for polymers, but less non-linear than for most glasses.

High fructose syrup production using fructose-selective liquid membranes

Fructose is separated from a fructose–glucose mixture using a polymer-supported liquid membrane containing a boronic acid carrier; addition of immobilized glucose isomerase to a solution of glucose in the source compartment of a liquid membrane transport cell produces a receiving phase mixture that is more than 80% fructose.

Glucose aversion in the German cockroach, Blattella germanica

A recently discovered strain of German cockroaches ( Blattella germanica L.) avoids ingesting toxicant/diet mixtures because of an aversion to d-glucose in the diet rather than to the toxicant. d-fructose stimulated feeding in glucose-averse cockroaches. However, only fructose-glucose mixtures with a molar ratio ≥ 9:1 fructose:glucose stimulated feeding. Rather than being learned, glucose aversion is inherited as an autosomal incompletely dominant trait, which appears to be controlled by a single major gene. This is the first report of nutrient avoidance as a resistance mechanism and of aversion to this typically phagostimulatory molecule recognized as the universal metabolic fuel.

High pressure adsorption and supercritical desorption of aqueous fructose-glucose mixtures

An adsorption system with the capability of processing a liquid, gas, or supercritical fluid stream was constructed and used to investigate the phase equilibrium and mass transfer behavior of the monosaccharides, fructose, and glucose. The compounds were first adsorbed onto activated carbon from an aqueous solution and then desorbed into a stream of supercritical carbon dioxide containing a small amount of ethanol to enhance solubility. Experiments were conducted at pressures 82.7 and 151.6 bar and temperatures 35, 50, and 65 °C. A mathematical model incorporating local mass transfer resistance and linear equilibrium isotherms was used to describe the movement of solute in the column. This model represents the experimental data well especially for the liquid phase. The ultimate capacity of activated carbon for both fructose and glucose is low. However, the two components are not adsorbed to the same extent. The relative selectivity of fructose over glucose ranges from 2–75 when adsorbing from aqueous solution, and from 2–300 when desorbing into supercritical carbon dioxide.

Separation of sugars by continuous annular chromatography

Continuous chromatographic separations of aqueous fructose-glucose-sucrose solutions have been investigated in a laboratory-scale continuous annular chromatograph (CAC) using calcium-exchanged Dowex 50W-X8 resin. Comparative studies have also been conducted using a conventional fixed-bed column packed with the same resin. Complete resolution of fructose-glucose mixtures could be obtained both in a 60-cm-long CAC and in a conventional column of the same length with a sugar feed concentration of up to 200 g/L. Partial resolution of sucrose in three component mixtures was also obtained, and the three sugars were completely separated from added higher-molecular-weight saccharides. Results have been analyzed in terms of approximate linear chromatographic theories and orthogonal collocation of exact mass transfer model equations for fixed and rotating beds. A systematic, comparative evaluation of factors affecting process performance and design procedures is presented.

A comparative study of zeolite and resin adsorbents for the separation of fructose-glucose mixtures

A comparative study of zeolite and resin adsorbents for the separation of fructose-glucose mixtures

Experimental study of a simulated counter-current adsorption system-V. Comparison of resin and zeolite absorbents for fructose-glucose separation at high concentration

The operation of a simulated counter-current adsorption process for separation of fructose-glucose mixtures has been studied experimentally at high concentration under conditions similar to those employed in the commercial process with both CaY zeolite and Duolite resin as the adsorbent. The overall performance of the system is similar for both adsorbents although the flow conditions required to achieve separation are significantly different. At high concentration the equilibrium isotherms deviate somewhat from linearity and this has an important effect on the concentration profile (and therefore the performance) of the counter-current unit. The equilibrium stage model, with due correction for the concentration dependence of the apparent distribution coefficients, is shown to provide a good representation of the system behaviour.

Numerical simulation of a semi-continuous counter-current adsorption unit for fructose-glucose separation

The transient and steady state behaviour of a semi-continuous counter-current adsorption unit, similar to the UOP “Sarex” process, for the separation of fructose-glucose mixtures has been simulated numerically and studied experimentally. Both transient and steady state concentration profiles are in good agreement with the predictions of a simple model in which the system is considered as a cascade of ideal theoretical stages, with the number of stages determined a priori from pulse chromatographic measurements.

Experimental study of a simulated counter-current adsorption system—IV. Non-isothermal operation

In an isothermal continuous counter-current adsorption separation process the product streams are generally diluted relative to the feed. However, this limitation does not apply to a non-isothermal system and it is shown that by applying a properly controlled temperature profile one may obtain the more strongly adsorbed species at a concentration substantially greater than the feed concentration. The practical feasibility of such a system is demonstrated experimentally for the separation of fructose-glucose mixtures. Under properly selected non-isothermal conditions an extract product containing 42% wt fructose (+2% glucose) was obtained from a feed mixture containing 24% of both fructose and glucose. The operation of the system and the proper choice of conditions can be understood by considering the McCabe-Thiele operating diagram.