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A decarbonylation free, polystyrene-supported, Pd (Pd@PS)-catalysed carbonylative esterification of the hydroxy group of 5-hydroxymethyl furfural (5-HMF) to its corresponding aryl esters has been developed. The use of Pd@PS, oxalic acid as CO source, and aryl halides was first explored for the aryl ester of 5-HMF synthesis. Here, we investigated the vital role of a polystyrene support to avoid the commonly known decarbonylation of 5-HMF. The reaction exhibits vast substrate scope with comparably good yield and catalyst recyclability.

5‐Hydroxymethylfurfural (HMF) is a promising bio‐derived platform chemical with a broad scope of application, for example, in the production of solvents, fuels, polymers, or adhesives. The wood and foundry industries are among the largest adhesive users and currently both rely to a large extent on the use of fossil‐based binders, such as by using formaldehyde as a crosslinker in many commercial adhesive systems. The industry is thus looking for suitable alternatives to replace fossil‐based chemicals. HMF and its derivatives are considered to be key renewable reactants in adhesive systems. The core of this Review is the critical evaluation of the potential of HMF and its derivatives in adhesive systems. The technological performance was assessed in the fields of wood‐based materials, sand casting and composites. As an overall conclusion, HMF and its derivatives have a high application potential in alternative adhesives. Clearly, further research is needed to improve the performance and produce economically competitive adhesives., Sticks like glue: This Review critically assesses the role of 5‐hydroxymethylfurfural (HMF) and its derivatives as renewable key reactants in adhesives. Application fields range from wood‐based materials, sand casting, and composites. The technological performance of many HMF‐based adhesives reaches the minimum requirements, but further research on economically feasible HMF‐based resins is needed.

Catalytic strategies were developed to synthesize and release chemicals for applications in fine chemicals, such as drugs and polymers, from a biomass-derived chemical, 5-hydroxymethyl furfural (HMF). The combination of the diene and aldehyde functionalities in HMF enabled catalytic production of acetalized HMF derivatives with diol or epoxy reactants to allow reversible synthesis of norcantharimide derivatives upon Diels-Alder reaction with maleimides. Reverse-conversion of the acetal group to an aldehyde yielded mismatches of the molecular orbitals in norcantharimides to trigger retro Diels-Alder reaction at ambient temperatures and released reactants from the coupled molecules under acidic conditions. These strategies provide for the facile synthesis and controlled release of high-value chemicals.

We demonstrated the capacity of Aspergillus nidulans to degrade HMF and related compounds and analysed the genetic basis of the degradation pathway. Gene deletion mutants confirmed that AN7164 encodes a furan‐2,5‐dicarboxylic acid decarboxylase in this fungus. The AN7164 orthogroup is not found widespread across distinct fungal classes, contrary to the AN4212 orthogroup (responsible for the direct transformation of HMF) that is widespread and highly redundant., Summary Hydroxymethylfurfural (HMF) is a promising lignocellulosic‐derived source for the generation of diverse chemical building blocks constituting an alternative to fossil fuels. However, it remains unanswered if ubiquitous fungi can ensure their efficient decay, similar to that observed in highly specialised fungi. To disclose the genetic basis of HMF degradation in aspergilli, we performed a comprehensive analysis of Aspergillus nidulans ability to tolerate and to degrade HMF and its derivatives (including an HMF‐dimer). We identified the degradation pathway using a suite of metabolomics methods and showed that HMF was modified throughout sequential reactions, ultimately yielding derivatives subsequently channelled to the TCA cycle. Based on the previously revealed hmfFGH gene cluster of Cupriavidus basilensis, we combined gene expression of homologous genes in Aspergillus nidulans and functional analyses in single‐deletion mutants. Results were complemented with orthology analyses across the genomes of twenty‐five fungal species. Our results support high functional redundancy for the initial steps of the HMF degradation pathway in the majority of the analysed fungal genomes and the assignment of a single‐copy furan‐2,5‐dicarboxylic acid decarboxylase gene in A. nidulans. Collectively our data made apparent the superior capacity of aspergilli to mineralise HMF, furthering the environmental sustainability of a furan‐based chemistry.

Background An antioxidant formula based on peanut skins and hulls was developed and characterized for total and single polyphenols, as well as antioxidant power, considering the contribution provided by each peanut by-product. Subsequently, it was evaluated for its effect on the sensory properties and aroma stability of peanut bars over a 100-day period. To this purpose, snacks fortified, or not, with the natural additive were experimentally produced. Results Peanut hulls contributed to a greater extent than skins with respect to boosting the content of bioactives and the antioxidnt activity of the antioxidant formula, which was marked by a phenol content of (approximately 807 mg gallic acid equivalents g-1 ) and a 2,2-diphenyl-1-picrylhydrazyl activity similar to that of butylated hydroxytoluene (85.96% and 89.30%, respectively). From a sensory perspective, the incorporation of the formulation in snacks caused only a slightly stronger perception of astringent and bitter notes. Pyrazines, phenol, furan and pyrrole derivatives defined the aroma of snacks, being more abundant in fortified than in conventional samples. Such volatiles faded over storage, with different trends in the examined products. For example, the sum of 2,5-dimethylpyrazine, 2-ethylpyrazine and 2,3-dimethylpyrazine was 9.49 and 8.87 ppm at day 15; 5.57 and 7.16 ppm at day 45; and 5.03 and 4.65 ppm at day 100, respectively, in fortified and conventional snacks. Hydroxymethylfurfural decreased constantly over storage in conventional samples and only after day 45 in fortified bars. Conclusion Overall, the antioxidant formulation did not compromise the sensory desirability of peanut snacks and induced a preservative effect on their aroma, especially during the first 15 days of storage. © 2020 Society of Chemical Industry.

Background Sterilization of milk is aimed at killing the microorganisms present. There are three main sterilization methods commonly used in milk processing: high temperature and short time (HTST) pasteurization, ultrahigh pasteurization (UP), and ultrahigh temperature (UHT) sterilization. The Maillard reaction is of special interest in studying the effect of heat treatment on milk quality. Furfural compounds are one of the typical intermediates of the Maillard reaction, which have safety risks related to mutagenic and genotoxic effects. The furfural compounds content is directly related to the heat treatment intensity. Results The furfural compounds content was measured using high-performance liquid chromatography with ultraviolet detection in 12 min. Then, 13 levels of heat treatment intensity (combinations of temperature and time) and three levels of homogenization pressure were selected to study the change of the furfural compounds content after different processing technologies in a pilot plant. The results show a higher temperature treatment can stimulate more Maillard reaction intermediates, such as hydroxymethylfurfural and furfural. A temperature regression evaluation model and content prediction models of hydroxymethylfurfural and furfural were developed to quantify the relationship between the furfural content and heat treatment with the data from the pilot plant. Conclusion Based on the temperature evaluation model, the heating temperature of three milk products was evaluated. The homogenization pressures had little effect on the furfural content in liquid milk. The emergence of the furyl methyl ketone and methylfurfural can be detected after overprocessing of the liquid milk. © 2020 Society of Chemical Industry.

This study aimed to analyze the botanical origin, quality parameters, phenolic compounds, and minerals of 20 honey samples from Caramulo region (Portugal). Six samples were monofloral from Eucalyptus sp., being this one the predominant pollen in the analyzed samples, followed by Castanea sativa. The average values obtained for the physicochemical parameters were as follows: 4.7 pH; 16.8% moisture; 81.4 Brix; 0.3% ash; 512.8 µS/cm electrical conductivity; 22.6 meq/kg free acidity; 12.4 meq/kg lactonic acidity; 35.1 meq/kg total acidity; 2.1 mg/kg hydroxymethylfurfural; and 16.3 °Gothe for diastase activities. A total of 18 phenolics were determined by high-performance liquid chromatography-diode array detector. Hydroxycinnamic acid derivatives and protocatechuic acid were the major ones. Nine minerals were detected by atomic absorption spectrometry; potassium and phosphorus were the predominant mineral elements. This is the first study about honeys from Caramulo region, which revealed to have a good quality and be a rich source of essential minerals and phenolics. PRACTICAL APPLICATION: The interest in the analysis of honey has increased significantly in recent years, concerning its characterization, safety implications, and health impact. Given these facts, the authentication of honeys, based on the geographical and botanical origins, has been assuming great importance, being mainly associated with high-quality honeys. Therefore, we decided to analyze physicochemical parameters, phenolic composition, and mineral content of 20 Caramulo honey samples. Our results indicate that Caramulo honeys possess high-quality levels, good freshness, maturity, and proper processing, and are also rich in several bioactive substances with health-promoting properties, including phenolic compounds, potassium, and phosphorus.

BACKGROUND: Effective cellulose hydrolysis has a huge potential for producing high value‐added biomass‐based platform chemicals, such as glucose, hydroxymethylfurfural, levulinic acid, and total reducing sugars (TRS). Particularly, a magnetic multifunctional solid acid catalyst (Fe₃O₄/Cl–MCMB–SO₃H) was synthesized by loading the active groups on the magnetic mesocarbon microbead (MCMB) derived from the co‐calcination of coal tar pitch and ferroferric oxide, which was applied as a catalyst in the conversion of cellulose into TRS. RESULTS: Given the superior properties of MCMB, a novel magnetic MCMB‐based solid acid with cellulose‐binding domain (–Cl group) and catalytic domain (–SO₃H group) was successfully prepared. Results indicated that this catalyst exhibited superior catalytic activity, recyclability and regenerability, and easy separation from the reactant. The acidic densities of –SO₃H and –Cl in Fe₃O₄/Cl–MCMB–SO₃H reached 1.77 and 1.32 mmol/g, respectively. The 68.6% TRS yield can be obtained from cellulose at 140 °C for 3 h in distilled water by using Fe₃O₄/Cl‐MCMB‐SO₃H as the catalyst. The TRS yield still reached 61.1% after the catalyst was used six times. Importantly, through catalyst regeneration, the –SO₃H density and TRS yield still reached 1.69 mmol/g and 67.3%, indicating that the catalyst exhibited excellent regenerability. CONCLUSION: Such multifunctional magnetic catalyst would be a promising catalyst in the conversion of cellulose into biofuels, which was attributed to the efficient catalytic performance, magnetism, and excellent recyclability and regenerability. © 2019 Society of Chemical Industry

The differences between a biorefinery and an oil refinery are determined by the higher oxygen content of the biorefinery´s biomass, its high degree of functionalization, its low thermal stability, its polar components, which are mostly acidic, its highly heterogeneous structure, and its quality variation as result of genotypic and phenotypic characteristics. Levulinic acid (LA) is one of the main high value-added chemicals that can be produced from lignocellulosic biomass as raw material. The main challenges for the conversion of lignocellulosic biomass to levulinic acid are related to the improvement of the technologies to obtain a pure and cost-competitive product, the design and use of efficient heterogeneous catalysts, and the improvements in the selectivity and useful life of the catalyst. This is an up-to-date review of the state of knowledge about the heterogeneous catalytic conversion of biomass into LA, addressing the technical hurdles that impede the attainment of high yields. This work outlines the chemistry of LA synthesis and discusses in detail the influence of the lignocellulosic raw material, reaction time, temperature, solvent according to the chemical pathway, and efficiency of the chosen Lewis and Brønsted solid acid catalysts. Fil: Covinich, Laura Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentina Fil: Clauser, Nicolás Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentina Fil: Felissia, Fernando Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentina Fil: Vallejos, María Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentina Fil: Area, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; Argentina

AIMS: The kinetics of Kelulut honey quality parameters of hydroxymethylfurfural (HMF), color intensity and total phenolic content (TPC) at dehydration temperatures of 40, 55, and 70°C up to 84 h were studied. METHODS: Data were fitted to zero‐, first‐, and second‐order kinetic models and regression analysis were performed to calculate rate constant and activation energy. RESULT: HMF increased following zero‐ and first‐order kinetics for 40 and 55°C, respectively. However, at 70°C, HMF first increased following zero‐order kinetics, peaked at 60 h and then decreased following first‐order kinetics. The color intensity of honey increased with dehydration time and was adequately described by zero‐order kinetics. The increase of TPC at lower dehydration temperature of 40 and 55°C followed zero‐order kinetics but at higher temperature of 70°C, was better fitted with first‐order model. CONCLUSIONS: The rate constants for all quality parameters increased with dehydration temperature, indicating that changes were more evident at higher temperature. The increase of TPC was found to be more evident due to its lower activation energy of 54.79 kJ/mol as compared to 104.1 and 63.16 kJ/mol for the increase of HMF and color intensity, respectively.

Aqueous-phase hydrodeoxygenation (APH) of bioderived feedstocks into useful chemical building blocks is one the most important processes for biomass conversion. However, several technological challenges, such as elevated reaction temperature (220-280 °C), high H2 pressure (4-10 MPa), uncontrollable side reactions, and intensive capital investment, have resulted in a bottleneck for the further development of existing APH processes. Catalytic transfer hydrogenation (CTH) under much milder conditions with non-fossil-based H2 has attracted extensive interest as a result of several advantageous features, including high atom efficiency (≈100 %), low energy intensity, and green H2 obtained from renewable sources. Typically, CTH can be categorized as internal H2 transfer (sacrificing small amounts of feedstocks for H2 generation) and external H2 transfer from H2 donors (e.g., alcohols, formic acid). Although the last decade has witnessed a few successful applications of conventional APH technologies, CTH is still relatively new for biomass conversion. Very limited attempts have been made in both academia and industry. Understanding the fundamentals for precise control of catalyst structures is key for tunable dual functionality to combine simultaneous H2 generation and hydrogenation. Therefore, this Review focuses on the rational design of dual-functionalized catalysts for synchronous H2 generation and hydrogenation of bio-feedstocks into value-added chemicals through CTH technologies. Most recent studies, published from 2015 to 2018, on the transformation of selected model compounds, including glycerol, xylitol, sorbitol, levulinic acid, hydroxymethylfurfural, furfural, cresol, phenol, and guaiacol, are critically reviewed herein. The relationship between the nanostructures of heterogeneous catalysts and the catalytic activity and selectivity for C-O, C-H, C-C, and O-H bond cleavage are discussed to provide insights into future designs for the atom-economical conversion of biomass into fuels and chemicals.

Background Vacuum evaporation (VE) process is widely utilized in fruit juice evaporation to preserve quality attributes of final product. However, it has some disadvantages such as possible degradation of aroma components or volatile fatty acids due to long process time, and low energy efficiency of process. Pomegranate juice having 17.5% total soluble solid (TSS) content was evaporated to 40% TSS by ohmic heating assisted vacuum evaporation (OVE; 7.5, 10 and 12.5 V cm-1 ) and VE in the present study. The effects of the evaporation methods on pH, titratable acidity and colour values, antioxidant activity (AA), total monomeric anthocyanin (TMA), total phenolic content (TPC), hydroxymethylfurfural (HMF) and invert sugar content of pomegranate juice concentrates were compared. Results The colour properties, TMA, TPC and AA values of pomegranate juice concentrates evaporated by OVE were more influenced than those evaporated by VE. The degradation of sugars was minimized for OVE processes at high voltage gradients (10 and 12.5 V cm-1 ), and HMF content of pomegranate juice concentrated by OVE was lower than VE. Conclusion It is thought that electrochemical reactions occurred because of the use of titanium electrodes during the OVE process caused these quality changes in pomegranate juice concentrates having high acidity. Hence, it was concluded that the utilization of relatively more electrochemically inert electrodes should be investigated in further studies to better evaluate the of influence of OVE method on quality attributes of different fruit juices. © 2018 Society of Chemical Industry.

Physicochemical characteristics, main minerals, and antioxidant activity were determined for Palestinian honey samples belonging to different floral and geographical origins. The features of the analyzed samples were within the established international standards for honey quality control. One clear exception was the hydroxymethylfurfural (HMF) of the Ziziphus sample purchased from the Jericho region, which is the lowest city in the word characterized by a hot desert climate. The observed HMF value was 81.86 ± 2.64 mg/kg being two folds the maximum allowed in honey samples (40 mg/kg). As a second objective of the present work, the parameters were divided into two groups with different discriminatory power. The assessed physicochemical parameters, and the antioxidant activities, specific to the botanical origin discrimination, were used to run the first PCA. A strong correlation could be seen between the bioactive compounds and the antioxidant activities despite the geographical origin of the samples. Thyme and Ziziphus samples were the best samples, while citrus sample presented the lowest activity. Regarding the geographical discrimination, Ash and mineral contents in addition to the electrical conductivity were used. The output PCA conserved high represent ability of the data in the two‐first components being 82.72% and 9.60%. A little discrimination between the samples produced in the north and those produced in the south of the country, but it was not perfect. The intervention of the botanical variability could be the reason.

Low-cost bagasse and microcrystalline cellulose were used as the raw materials to prepare solid acid catalysts via incomplete carbonization and sulphonation. The solid acid synthesized from microcrystalline cellulose (C-SO3H) exhibited better catalytic performance than that synthesized from bagasse. C-SO3H was characterized by various techniques to study the reaction conditions of the catalytic transformation from glucose and fructose to 5-hydroxymethylfurfural (5-HMF). The conversion of glucose was 73.29 ± 0.74 %, and the conversion of fructose reached a maximum of 98.85 ± 0.01 %. The selectivity and yield of 5-HMF reached maxima of 65.04 ± 0.28 % and 64.29 ± 0.27 %, respectively. Using C-SO3H as the catalyst, the conversion of glucose followed second-order kinetics at various temperatures, while the conversion of fructose followed first-order kinetics. The activation energies of the glucose and fructose transformations were 73.75 and 51.87 kJ·mol−1, respectively. This article is protected by copyright. All rights reserved

Thermal degradation and generation of objectionable compounds such as hydroxymethylfurfural have been observed in hot pressurised water extraction of polyphenols. Addition of small amounts of ethanol can reduce process temperatures and retain extraction

Chitin and chitosan polymers are a valuable source of functional chemicals and materials. Chemical and/or enzymatic depolymerisation processes have been developed for the production of chitooligosaccharides (COS), N‐acetylglucosamine (GlcNAc) and glucosamine (GlcN), which have a wide variety of applications. New technologies are now emerging to convert chitin and its derivatives into platform chemicals. Chemical liquefaction of chitin can lead to bulk chemicals like acetic acid and platform chemicals like hydroxymethylfurfural (HMF) and amine‐containing monomers for polymers, in low yield. The monomers GlcNAc and GlcN can be converted into N‐containing HMF derivatives, opening a pathway for furan‐based monomers for polyamides. Selective catalytic oxidation of GlcN results in the production of D‐glucosaminic acid (DGA). This acid is a valuable building block for the synthesis of various amino acids for biomedical applications and bio‐based chiral polyamides. Further technological improvements are necessary to increase the selectivity and efficiency of reactions, particularly for the conversion of polymeric chitin and chitosan into building blocks.

Exploring high-performance base-metal approaches for the sustainable production of chemicals from biomass is presently attracting immense interest and is truly important to promote their industrialized application. Herein, CoOx-N/C and α-MnO2 were combined as a base-metal catalyst that can achieve high yields of furan-2,5-dimethylcarboxylate (FDMC, 95.6 %) for the catalytic oxidative esterification of 5-hydroxymethylfurfural (HMF) without basic additive. The reaction proceeds through fast conversion of HMF to diformylfuran (DFF) with α-MnO2 and subsequent transformation of DFF to FDMC by CoOx-N/C. Quantitative X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations indicated that the pyridinic-N present in doped carbon could behave as a Lewis base to promote the abstraction of hydrogen for the oxidative esterification reaction. Consequently, CoOx-N/C is a high performance catalyst for the synthesis of FDMC from DFF in a neutral medium.

The goal of this study was to produce ethanol from rice hull hydrolysates (RHHs) using Pichia stipitis strains and to optimize dilute acid hydrolysis and detoxification processes by response surface methodology (RSM). The optimized conditions were found as 127.14°C, solid:liquid ratio of 1:10.44 (w/v), acid ratio of 2.52% (w/v), and hydrolysis time of 22.01 min. At these conditions, the fermentable sugar concentration was 21.87 g/L. Additionally, the nondetoxified RHH at optimized conditions contained 865.2 mg/L phenolics, 24.06 g/L fermentable sugar, no hydroxymethylfurfural (HMF), 1.62 g/L acetate, 0.36 g/L lactate, 1.89 g/L glucose, and 13.49 g/L fructose + xylose. Furthermore, RHH was detoxified with various methods and the best procedures were found to be neutralization with CaO or charcoal treatment in terms of the reduction of inhibitory compounds as compared to nondetoxified RHH. After detoxification procedures, the content of hydrolysates consisted of 557.2 and 203.1 mg/L phenolics, 19.7 and 21.60 g/L fermentable sugar, no HMF, 0.98 and 1.39 g/L acetate, 0 and 0.04 g/L lactate, 1.13 and 1.03 g/L glucose, and 8.46 and 12.09 g/L fructose + xylose, respectively. Moreover, the base-line mediums (control), and nondetoxified and detoxified hydrolysates were used to produce ethanol by using P. stipitis strains. The highest yields except that of base-line mediums were achieved using neutralization (35.69 and 38.33% by P. stipitis ATCC 58784 and ATCC 58785, respectively) and charcoal (37.55% by P. stipitis ATCC 58785) detoxification methods. Results showed that the rice hull can be utilized as a good feedstock for ethanol production using P. stipitis. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:872-882, 2016.

Summary This work aimed to investigate the reactivity of hydroxymethylfurfural (HMF) with selected amino acids, to identify the produced adducts and to clarify whether or not the adducts release HMF after their digestion under gastric conditions. Results showed that cysteine, glycine and lysine can deplete the added HMF, and their reactivity increased with increasing pH and temperature. Cysteine (25 μmol mL−1) depleted 91.0% of the added HMF (315.3 μg mL−1) at 40 °C in 15 min, lysine did not eliminate HMF until 80 °C, and glycine started to eliminate HMF at 100 °C. Four adducts for cysteine, three adducts for lysine and only one adduct for glycine were identified through HPLC–MS–MS after they reacted with HMF. The adducts formed from the reaction mixture of cysteine, lysine and glycine with HMF only released 1.7%, 2.6% and 10.5% of eliminated HMF, respectively, after their digestion in simulated gastric conditions.

The adsorption of biogenic hydroxymethylfurfural and fructose from aqueous phase reaction mixtures on polymer-based spherical activated carbons was studied. The adsorbents show a high capacity in combination with an outstanding selectivity due to their hydrophobic surface. Equilibrium isotherms and breakthrough curves of single and multicomponent solutions as well as the desorption behavior were measured and modelled accordingly. Overall, the results obtained enable further process development for adsorptive liquid phase separation in future biorefinery processes.

2,5-furandicarboxylic acid (FDCA) is one of the top platform chemicals that can be produced from biomass feedstock. To make the cost of industrial FDCA production compatible with plastics made from fossils, the price of substrates and process complexity should be reduced. The aim of this research is to create a CO2 -driven syntrophic consortium for the catalytic conversion of renewable biomass-derived 5-hydroxymethylfurfural (HMF) to FDCA. Sucrose produced from carbon fixation by the engineered Synechococcus elongatus serves as the sole carbon source for the engineered Pseudomonas putida to catalyze the reaction of HMF to FDCA. The yield of FDCA by the consortium reaches around 70% while the conversion of HMF is close to 100%. With further surface engineering to clump the two strains, the FDCA yield is elevated to almost 100% via the specific association between an Src homology 3 (SH3) domain and its ligand. The syntrophic consortium successfully demonstrates its green and cost-effective characteristics for the conversion of CO2 and biomass into platform chemicals.

Homogeneous (HCl) and heterogeneous catalysts (various zeolites) were combined to enhance the upgrading of glucose into two different platform molecules: 5-hydroxymethylfurfural (HMF) and levulinic acid (LA). β-Zeolite was the most active material for the glucose isomerization to fructose, improving also the activity of HCl for the subsequent steps. Reaction time, temperature, and pH were then modified, identifying 140 °C, 200 ppm of HCl, and 5 h as the optimum conditions for HMF formation (41 % selectivity; 0.06 mol L-1 ) and 140 °C, 400 ppm of HCl, and 24 h for LA formation (34 % selectivity; 0.12 mol L-1 ). This new approach is also relevant because of significant changes to the mechanism for humins formation. All results are successfully fitted to a kinetic model simultaneously considering both catalytic mechanisms.

Stable oil-in-water high internal phase emulsions (HIPEs) with an internal phase volume fraction of 85 % were stabilized using Tween 85. The prepared poly(HIPEs) were first investigated as adsorbents to treat water polluted with CrIII, and then the catalysts with Lewis acidic sites was synthesized. The catalysts with Bronsted acidic sites were obtained by ion-exchanging. The as-prepared HIPEs–CrIII (PEs–CrIII) and HIPEs–SO3H (PEs–SO3H) possess open-cell structure, interconnecting pores, and strong acidity, they are utilized as highly efficient catalysts for the conversion of biomass to 5-hydroxymethylfurfural (HMF). These results showed maximum production yields for cellulose, glucose, and fructose of 37.0 %, 58.0 %, and 80.8 %, respectively. PEs–CrIII and PEs–SO3H can be very easily recycled at least four times without significant loss of activity. Herein, a new method is presented to transform cellulose by using two catalysts in a one-pot process for meeting the varying demands involved at different reaction stages.

Reaction kinetics were studied to quantify the effects of water on the conversion of hydroxymethylfurfural (HMF) in THF over Cu/γ-Al2 O3 at 448 K using molecular H2 as the hydrogen source. We show that low concentrations of water (5 wt %) in the THF solvent significantly alter reaction rates and selectivities for the formation of reaction products by hydrogenation and hydrogenolysis processes. In the absence of water, HMF was converted primarily to hydrogenolysis products 2-methyl-5-hydroxymethylfuran (MHMF) and 2,5-dimethylfuran (DMF), whereas reactions carried out in THF-H2 O mixtures (THF/H2 O=95:5 w/w) led to the selective production of the hydrogenation product 2,5-bis(hydroxymethyl)furan (BHMF) and inhibition of HMF hydrogenolysis.

Institute of Chemistry, Sao Paulo State University - UNESP, Campus Araraquara, Department of Analytical Chemistry, Jardim Quitandinha, Araraquara, SP, Brazil.

2,5-Furandicarboxylic acid (FDCA) is considered to be a promising replacement for terephthalic acid since they share similar structures and properties. In contrast to FDCA, 2,5-furandicarboxylic acid methyl (FDCAM) has properties that allow it to be easily purified. In this work, we reported an oxidative esterification of 5-hydroxymethylfurfural (HMF) and furfural to prepare corresponding esters over Cox Oy -N@C catalysts using O2 as benign oxidant. High yield and selectivity of FDCAM and methyl 2-furoate were obtained under optimized conditions. Factors which influenced the product distribution were examined thoroughly. The Cox Oy -N@C catalysts were recycled five times and no significant loss of activity was detected. Characterization of the catalysts could explain such phenomena. Using XPS and TGA, we made a thorough investigation of the effects of ligand and pyrolysis temperature on catalyst activity.

Summary This work was undertaken to assess the effects of high-pressure processing on brown pigment formation, antibacterial activity and hydroxymethylfurfural (HMF) content in Manuka honey. The honey was subjected to different pressures (200400 MPa) at ambient temperatures (25-33 "C) and with moderate temperatures (53-74 "C) for holding times (10-30 min). The brown pigment formation in high-pressuretreated sample showed a significant increase (0.16-0.17, P 0.05). Thus, high-pressure processing has no adverse effect on the honey quality because it can control HMF concentration during process. Increasing brown pigment formation is associated with the enhancement of antibacterial activity.

The presence of the highly toxic furfural and hydroxymethylfurfural (HMF) in the hydrolysate of lignocellulosic biomass prompted the investigation of the Escherichia coli ΔacrR regulatory mutant for higher tolerance to these compounds, to facilitate the production of biofuels and biochemicals, and further biocatalytic conversions. In comparison with the parental strain, the regulatory mutant with the upregulated efflux pump AcrAB-TolC produced moderately better growth and higher tolerance to concentrations of furfural and HMF between 1 and 2 g L(-1) .

[Scope] Scarce data are available concerning effects of certain bioactive substances such as Maillard reaction products (MRP) on the gut microbiota composition, and the question of how a diet rich in MRP affects gut microbiota in humans is still open., [Methods and results] Two experiments were conducted. In expt. 1, adolescents consumed diets either high or low in MRP in a two-period crossover trial; in expt. 2, rats were fed diets supplemented or not with MRP model-systems. Intestinal microbiota composition in fecal (adolescents) or cecal (rat) samples was assessed by qPCR analysis. Negative correlations were found in the human assay between lactobacilli numbers and dietary advanced MRP (r = −0.418 and −0.387, for hydroxymethylfurfural and carboxymethyl-lysine respectively, p < 0.05), whereas bifidobacteria counts were negatively correlated with Amadori compounds intake. In the rat assay, total bacteria and lactobacilli were negatively correlated with MRP intake (r = −0.674,−0.675 and −0.676, for Amadori compounds, hydroxymethylfurfural and carboxymethyl-lysine respectively, p < 0.05), but no correlations were found with bifidobacteria., [Conclusions] Dietary MRP are able to modulate in vivo the intestinal microbiota composition both in humans and in rats, and the specific effects are likely to be linked to the chemical structure and dietary amounts of the different browning compounds., This work was carried out with financial support from the Spanish MINECO (AGL2010-15235 and PET2008-0311). MJP is recipient of a JAE pre CSIC grant. This research has been also partially supported by the FEDER and FSE funds from the European Union.

Agro-residues and their hydrolyzates are precursors for synthesis of biofuels and mesoporous carbons. However, factors like pH, biomass loading, temperature, and enzyme affect the recovery of carbon sugars, and limit the hydrolysis. This study determined the main factors affecting the hydrolysis by Principal Component Analysis (PCA). Corn cob was added to 1.2% hydrochloric acid and subjected to steam at 121 °C, 20 min (low-severity, Step 1) following enzymatic hydrolysis (Step 2). Factor levels i.e., pH (4.5-7.5), temperature (37, 45, 55 °C), biomass loading (50, 100, 200 g/L) and enzyme type (Viscozyme L and Cellulase, Sigma) were adjusted in Step 2. PCA of standardized measured variables (glucose, xylose, arabinose, reducing sugars (RS) and hydroxymethylfurfural (HMF) concentrations; and yields of glucose, xylose and RS) at various factor levels was performed. Principal component 1 and 2 could explain ca. 96% of the data variance (Fig. 1). Low biomass loading correlated with high yields of glucose, xylose and RS, whereas pH 5.5, 45 °C and cellulase correlated with high concentrations of glucose, xylose and RS. PCA can be an effective tool in the design of efficient hydrolysis method and evaluation of factors affecting pretreatment method.

The influence of transglutaminase (TGase) on the Maillard reaction was investigated in skimmed milk samples during heat treatment. TGase-treated and control samples were heated at 80, 120 and 140 °C for 1, 5, 15, 30, 40 and 60 min. Compared with the TGase-treated samples heated at 80 and 120 °C, the sample heated at 140 °C showed a larger decrease in furosine concentration. It was also found that TGase did not affect the formation of hydroxymethylfurfural and lactulose at 120 °C, whereas their concentrations increased in the presence of TGase at 140 °C. It was concluded that blockage of lysine residues via enzymatic cross-linking of milk proteins had a limited effect on the Maillard reaction.

Hydroxymethylfurfural (HMF) is viewed as a potential platform material to make a variety of chemicals and products out of renewable resources. In this work, a complete ionic liquid reaction and separation process is presented for nearly stoichiometric conversion of fructose into HMF. The silicalite adsorbent material is demonstrated for separation of 99% pure HMF out of ionic liquid reaction mixtures through a packed column and for recovery of the unconverted sugars and reaction intermediates along with the ionic liquid. Membrane-coated silicalite particles are prepared and studied for a practical adsorption process with separation performances comparable to or better than the powder material. It is discovered that nearly all the fresh fructose feed could be converted into HMF with the recycled ionic liquid under suitable reaction conditions. These research results lead to a new HMF production process much simpler than the current paraxylene manufacturing process from petroleum oil. © 2013 American Institute of Chemical Engineers AIChE J, 60: 300–314, 2014

Summary The changes of bioactive components and antioxidant activity of quince nectar were determined during 9 months of storage at 5, 20, 30 and 40 °C. The amount of total phenolics, flavonoids and antioxidant activity was significantly declined during storage at all temperatures. Loss of L-ascorbic acid at 5, 20, 30 and 40 °C was 32.08%, 43.69%, 65.21% and 88.82%, respectively. L-ascorbic acid degradation was in accordance with the first-order reaction kinetics, and activation energy was found as 43.65 kJ mol−1. After 9 months of storage, Hydroxymethylfurfural (HMF) contents of quince nectars were 15.01, 16.64, 21.69 and 57.89 mg kg−1 at 5, 20, 30 and 40 °C, respectively. HMF accumulation fitted a zero-order kinetic model, and activation energy was found as 88.30 kJ mol−1. A significant correlation was found among L-ascorbic acid, total phenolics, flavonoids and antioxidant activity.

A new class of biodegradable anionic surfactants with structures based on 5-alkoxymethylfuroate was prepared starting from 5-hydroxymethylfurfural (HMF), through a one-pot-two-steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H-Beta, HY, Mordenite, ZSM-5, ITQ-2, and MCM-41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect-free H-Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self-etherification of HMF. Moreover, the 5-alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H-Beta zeolite and Au/CeO2 could be reused several times without loss of activity., The authors acknowledge the Spanish Ministry of Education and Science for the financial support in the project Consolider-Ingenio 2010 and CTQ.-2011-27550. K. S. A. thanks Universidad Politecnica de Valencia and ITQ for FPI fellowships.

Electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) or other species, such as 2,5-dimethylfuran, on solid metal electrodes in neutral media is addressed, both in the absence and in the presence of glucose. The reaction is studied by combining voltammetry with on-line product analysis by using HPLC, which provides both qualitative and quantitative information about the reaction products as a function of electrode potential. Three groups of catalysts show different selectivity towards: (1) DHMF (Fe, Ni, Ag, Zn, Cd, and In), (2) DHMF and other products (Pd, Al, Bi, and Pb), depending on the applied potential, and (3) other products (Co, Au, Cu, Sn, and Sb) through HMF hydrogenolysis. The rate of electrocatalytic HMF hydrogenation is not strongly catalyst-dependent because all catalysts show similar onset potentials (-0.5 ± 0.2 V) in the presence of HMF. However, the intrinsic properties of the catalysts determine the reaction pathway towards DHMF or other products. Ag showed the highest activity towards DHMF formation (up to 13.1 mM cm(-2) with high selectivity> 85%). HMF hydrogenation is faster than glucose hydrogenation on all metals. For transition metals, the presence of glucose enhances the formation of DHMF and suppresses the hydrogenolysis of HMF. On poor metals such as Zn, Cd, and In, glucose enhances DHMF formation; however, its contribution in the presence of Bi, Pb, Sn, and Sb is limited. Remarkably, in the presence of HMF, glucose hydrogenation itself is largely suppressed or even absent. The first electron-transfer step during HMF reduction is not metal-dependent, suggesting a non-catalytic reaction with proton transfer directly from water in the electrolyte.

Lignocellulosic biomass has become an important feedstock to mitigate current ethical and economical concerns related to the bio-based production of fuels and chemicals. During the pre-treatment and hydrolysis of the lignocellulosic biomass, a complex mixture of sugars and inhibitors are formed. The inhibitors interfere with microbial growth and product yields. This study uses an adaptive laboratory evolution method called visualizing evolution in real-time (VERT) to uncover the molecular mechanisms associated with tolerance to hydrolysates of lignocellulosic biomass in Saccharomyces cerevisiae. VERT enables a more rational scheme for isolating adaptive mutants for characterization and molecular analyses. Subsequent growth kinetic analyses of the mutants in individual and combinations of common inhibitors present in hydrolysates (acetic acid, furfural, and hydroxymethylfurfural) showed differential levels of resistance to different inhibitors, with enhanced growth rates up to 57%, 12%, 22%, and 24% in hydrolysates, acetic acid, HMF and furfural, respectively. Interestingly, some of the adaptive mutants exhibited reduced fitness in the presence of individual inhibitors, but showed enhanced fitness in the presence of combinations of inhibitors compared to the parental strains. Transcriptomic analysis revealed different mechanisms for resistance to hydrolysates and a potential cross adaptation between oxidative stress and hydrolysates tolerance in several of the mutants. Biotechnol. Bioeng. 2013;110: 2616–2623. © 2013 Wiley Periodicals, Inc.

BACKGROUND:TheMaillardreactionindicatorsfurosine,hydroxymethylfurfural(HMF),acrylamideandcolorweredetermined to evaluate heat effects induced during extrusion, infrared and microwave heating of soybean. In addition, the present paper aimed to study changes in the phenolic compounds, as well as in the overall antioxidant properties of different soybean products in relation to heating at 45‐140 ◦ C during the processes. RESULTS: Soybean proteins were highly sensible to Maillard reaction and furosine was rapidly formed under slight heating conditions during extrusion and infrared heating. Microwave heating at lower temperatures for a longer time yielded lower acrylamide levels in the final soybean products, as a result of its partial degradation. However, during infrared heating, acrylamide formation greatly increased with decreasing moisture content. After a short time of extrusion and infrared heating at 140 ◦ C and microwave heating at 135 ◦ C for 5min, concentrations of HMF increased to 11.34, 26.21 and 34.97 µgg −1 , respectively. CONCLUSION: The heating conditions caused formation of acrylamide, HMF and furosine in high concentration. The results indicate that the complex structure of soybeans provides protection of phenolic compounds from thermal degradation, and that Maillard reaction products improved the antioxidant properties of heat-treated soybean. c � 2013 Society of Chemical Industry

Twenty-four samples of Apis mellifera honey and twenty-four samples of Melipona subnitida (Jandaira) honey were collected in the northeast of Brazil. Moisture, hydroxymethylfurfural, free acidity, insoluble solids in water, diastase activity, ashes, electrical conductivity, proteins, lipids, total carbohydrates, energy and sugars were the parameters analysed. The efficiency of the qualitative tests (Fiehe’s test, Lugol’s reaction, Lund’s reaction) was tested. Pollen types and the corresponding plant species were identified in all samples (3 in Apis and 1 in Melipona). Apis mellifera honey samples demonstrated parameters in accordance with the Brazilian Legislation, while the Melipona subnitida honey samples displayed moisture (24.80%) and diastase activity (null) in discordance with the established by the regulation for Apis mellifera honeys. Apis honey samples presented higher values of electric conductivity (284.00 lS cm 1 ) than the obtained from the Jandaira honey samples (102.77 lS cm 1 ) as well as a darker colour (26.67 mmPfund) when compared with Jandaira honey (7.00 mmPfund). The concentration of the glucose, fructose and sucrose was higher in the Apis honeys than in the Jandaira honey. The characteristics of the two types of honey were very different, highlighting the need of developing specific legislation for stingless bees’ honey.

Mixed noblility: We show that the modification of a gold/carbon catalyst with platinum or palladium produces stable and recyclable catalysts for the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA): the support and nanoparticle chemistry directly mediate the selective oxidation of terminal hydroxyl groups in bio-derived HMF. This finding is a significant advance over current conversion technology because of the technological importance of FDCA.

Different biobased chemicals are produced during the conversion of biomass into fuels through various feasible technologies (e.g., hydrolysis, hydrothermal liquefaction, and pyrolysis). The challenge of transforming these biobased chemicals with high hydrophilicity is ascribed to the high water content of the feedstock and the inevitable formation of water. Therefore, aqueous-phase processing is an interesting technology for the heterogeneous catalytic conversion of biobased chemicals. Different reactions, such as dehydration, isomerization, aldol condensation, ketonization, and hydrogenation, are applied for the conversion of sugars, furfural/hydroxymethylfurfural, acids, phenolics, and so on over heterogeneous catalysts. The activity, stability, and reusability of the heterogeneous catalysts in water are summarized, and deactivation processes and several strategies are introduced to improve the stability of heterogeneous catalysts in the aqueous phase.

The formation of hydroxymethylfurfural, nonenzymatic brown coloured compounds and free sulphydryl groups in goat milk was studied during heating at 75–95 � C. Analysis of kinetic data suggested that formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds followed zero order reaction kinetics, while formation of free sulphydryl groups during heating varied depending on heating time. A good linear correlation (r = 0.839) was found between brown coloured compounds and hydroxymethylfurfural content in milk samples during heating. Activation energies (Ea) for the formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds were 96.31 and 69.79 kJ ⁄mol, respectively.

The Maillard reaction is one of the most important phenomena occurring spontaneously during food processing and storage. However, research on the effects of Maillard reaction products (MRPs) on starch hydrolysis remains insufficient. To investigate the effects of MRPs on in vitro starch digestibility, the characteristics of glucose–glycine model system containing MRPs and digestive enzyme activities by MRPs were measured. MRPs were prepared by heating of glucose–glycine mixture solution at 90°C for different times (0, 1, 3, 9, 18, 24, and 48 h). As the Maillard reaction proceeded, browning intensity, and furosine and hydroxymethylfurfural content increased, whereas pH value decreased. The reducing power of MRPs was increased as the Maillard reaction progressed, and MRPs produced in 18 and 24 h showed the highest values (both 1.2). In MRPs heated for 48 h, the reducing sugar content and hydrolysis index were lowest values (88.6 and 87.0%) among the samples. The activity of digestive enzymes significantly decreased by adding of MRPs, as the browning of added MRPs increased. Therefore, MRPs seem to be contributed to decrease in starch digestibility, as shown by an enzymatic digestion result.