HMF Formation Research Articles

The Role Played by Ionic Liquids in Carbohydrates Conversion into 5-Hydroxymethylfurfural: A Recent Overview.

Obtaining industrially relevant products from abundant, cheap, renewable, and low-impacting sources such as lignocellulosic biomass, is a key step in reducing consumption of raw fossil materials and, consequently, the environmental footprint of such processes. In this regard, a molecule that is similar to 5-hydroxymethylfurfural (5-HMF) plays a pivotal role, since it can be produced from lignocellulosic biomass and gives synthetic access to a broad range of industrially important products and polymers. Recently, ionic liquids (ILs) have emerged as suitable solvents for the conversion of biomass and carbohydrates into 5-HMF. Herein, we provide a bird’s-eye view on recent achievements about the use of ILs for the obtainment of 5-HMF, covering works that were published over the last five years. In particular, we first examine reactions involving homogeneous catalysis as well as task-specific ionic liquids. Then, an overview of the literature addressing the use of heterogeneous catalysts, including enzymes, is presented. Whenever possible, the role of ILs and catalysts driving the formation of 5-HMF is discussed, also comparing with the same reactions that are performed in conventional solvents.

Natural Antioxidants and Hydrocolloids as a Mitigation Strategy to Inhibit Advanced Glycation End Products (AGEs) and 5-Hydroxymethylfurfural (HMF) in Butter Cookies.

Maillard reaction during food processing contributes to the formation of some unpleasant heat-induced toxicants including advanced glycation end products (AGEs) and 5-hydroxymethylfurfural (HMF). The current study prepared butter cookies fortified with two dietary natural antioxidants (catechins and curcumin) and two dietary hydrocolloids (pectin and chitosan), and investigated their effects on formation of free Nε-(carboxymethyl)lysine (CML)/Nε-(carboxyethyl)lysine (CEL), protein-bound CML/CEL and HMF and on the sensory qualities of butter cookies. Meanwhile, three typical α-dicarbonyl compounds were also determined to identify possible correlations between α-dicarbonyl intermediates and formation of these harmful heat-induced products in butter cookies. Experimental data showed that catechin exhibited the strongest inhibitory effects on formation of AGEs and HMF, but its addition would impair the color and taste of cookies. On the other hand, chitosan was not so effective in inhibiting AGEs and HMF as compared to catechin, but its addition could increase the sensory qualities of butter cookies.

Gallic Acid Mitigates 5-Hydroxymethylfurfural Formation while Enhancing or Preserving Browning and Antioxidant Activity Development in Glucose/Arginine and Sucrose/Arginine Maillard Model Systems.

The current trend of lowering 5-hydroxymethylfurfural (5-HMF) dietary exposure is challenging since its formation is parallel with the development of food color, flavor and aroma. We aimed to investigate the effect of gallic acid (GA) addition on 5-HMF formation, color development and antioxidant activity (AA) in a series of Maillard Reaction (MR) model systems. The effects of GA addition on browning and AA development were not uniform for all model systems, but always occurred in the same direction, indicating that these phenomena were interconnected. GA mitigated 5-HMF development in four of the nine tested systems, possibly by preventing the oxidation of MR intermediates. Correlation analysis indicated that when GA addition mitigated 5-HMF formation, browning was either promoted or not affected. The proposed strategy was effective for glucose/arginine and sucrose/arginine systems, since GA mitigated 5-HMF formation (49% and 54%, respectively) in addition to increasing color development and antioxidant activity.

Investigation of thermal contaminants in coffee beans induced by roasting: A kinetic modeling approach

The roasting-induced formation of thermal contaminants in coffee beans, including 5-hydroxymethylfurfural (5-HMF), acrylamide (AA), furan (F), 2-methyl furan (2-MF), and 3-methyl furan (3-MF), was investigated using a kinetic modeling approach. Results showed that AA and 5-HMF formation and elimination occur simultaneously in coffee beans during roasting and that the related reactions follow first-order reaction kinetics. The concentrations of F, 2-MF, and 3-MF increased throughout the roasting experiment, and variations in the concentrations of these compounds during roasting could be best described by empirical, logistic model. The increase in weight loss and decrease in moisture content of the beans during roasting also displayed first-order reaction kinetics. High coefficients of determination (R2 > 0.981) were observed for all fitted models, and the reaction rate constants of all models followed the Arrhenius law.

Effects of baking factors and recipes on the quality of butter cookies and the formation of advanced glycation end products (AGEs) and 5-hydroxymethylfurfural (HMF)

Maillard reaction during food processing contributes to the formation of some unpleasant heat-induced toxicants including advanced glycation end products (AGEs) and 5-hydroxymethylfurfural (HMF), which have been linked to various health risks. The effects of baking factors and recipes, such as baking temperature (130°C–180 °C) and time (8 min–15 min), sucrose levels (0 g–20 g), butter levels (0 g–20 g) and egg liquid levels (0 g–12 g) on the formation of free Nε-(carboxymethyl)lysine (CML), free Nε-(carboxyethyl)lysine (CEL), protein-bound CML, protein-bound CEL, HMF, glyoxal (GO), methylglyoxal (MGO), 3-deoxyglucosone (3-DG) and on the sensory qualities were investigated in butter cookies. The results suggested that the levels of AGEs initially increased and then followed by decrease as baking temperature and time increased, HMF is very sensitive to baking temperature and time and grows sharply. The changes of protein-bound AGEs are lagging behind that of free AGEs. The proportions of sucrose, butter and egg liquid in butter cookies were positively correlated with AGEs, with sucrose greatly promoting on the formation of HMF and 3-DG. In addition, the high level of sucrose and butter in cookies is preferred by panelists, especially in terms of appearance, taste and smell.

Comparison of buffalo’s, sheep’s and goat’s yoghurts in terms of their antioxidant activity, angiotensin-converting enzyme (ACE) inhibitory activity, volatile compound content and 5-hydroxymethylfurfural (HMF) content

This study examined yoghurt samples produced using classical yoghurt culture from buffalo’s, goat’s and sheep’s milks in terms of their physicochemical characteristics, DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity, angiotensin-converting enzyme (ACE) inhibitory activity, and contents of total phenolic compounds (TPC), volatile compounds and 5-hydroxymethylfurfural (HMF). It was determined that the use of different types of milk in yoghurt production had a statistically very significant effect (p <0.01) on all physicochemical and biochemical properties analyzed, whereas the storage period had a very significant effect (p <0.01) on pH and titratable acidity. Compared to other types of milk, sheep’s milk was found to be superior in terms of antioxidant activity and ACE inhibitory activity, whereas buffalo’s milk was found to be superior in its content of volatile compounds. The highest HMF formation was observed in yoghurt samples produced from goat’s milk. It is therefore suggested that the consumption of yoghurts produced from different types of milk should be expanded because of their nutritional value and bioactivity.

Sweet pomegranate pekmez production: Effect of different production methods and activated carbon treatment on some quality parameters and 5‐hydroxymethyl furfural formation

In the present study, “sweet pomegranate pekmez” (PP), was produced by three different methods as open pan evaporation (OPE), application of activated carbon prior to open pan evaporation (AC), and vacuum evaporation (VE). The effects of activated carbon treatment and production methods on pH, density, soluble solids, water activity, total phenolic content, HMF formation, mineral content, and texture characteristics were investigated. Textural properties of PP increased with increasing soluble solids content. HMF was not detected in AC and VE products. HMF content of OPE product was measured as 2.77 ± 0.28 mg.100 g. Activated carbon treatment resulted in significant reductions in mineral, HMF, and TPC contents of pekmez samples. HMF formation kinetics of PP was investigated at various accelerated storage temperatures. HMF formation was well described by the zero-order reaction model among five kinetic models applied. The rate of reaction was determined as highly temperature-dependent by an Arrhenius equation. Practical applications In recent years, consumer interest and demand for potentially health-promoting products has motivated the production of such food products. In this context, in this study, sweet pomegranate pekmez is introduced as a potentially healthy product produced by different methods, and the production stages and conditions that may enlighten the industrial production of this traditional product are provided. In addition, the application of activated carbon used in the production of pekmez has been presented as an alternative method to reduce the potential formation of HMF during heat treatment.

Hafnium-tin composite oxides as effective synergistic catalysts for the conversion of glucose into 5-hydroxymethylfurfural

5-Hydroxymethylfurfural (5-HMF), an important and value-added platform chemical, has inspired increasing attention. In this study, hafnium-tin composite oxides (Sn-HfO2) were prepared by one-pot coprecipitation process and used as effective synergistic catalysts for 5-HMF synthesis from the conversion of glucose. Pyridine-FTIR results reveal that Sn-HfO2 catalysts have strong Lewis and weak Brønsted acid sites. With 0.5Sn-HfO2 as the catalyst, the highest yield of 5-HMF obtained from glucose was 75.5% with 99.5% conversion at 170 °C for 2 h in a methyl isobutyl ketone (MIBK)/water biphasic system. Furthermore, the catalytic system also possesses excellent performance in converting other carbohydrates. The catalysis mechanism for the isomerization of glucose to fructose was explored by the density functional theory (DFT) method, indicating that Lewis acidic Hf active sites and proton mediator Sn-O species synergistically catalyzed the isomerization process, effectively lowering the reaction energy barrier. The cooperative action of terminal Hf-OH and Sn-OH also facilitated the formation of 5-HMF in fructose dehydration. 0.5Sn-HfO2 could be reused for four runs without significant loss of catalytic activity. This approach provides the feasibility of composite oxides as synergistic catalysts for carbohydrate conversion to 5-HMF.

Effect of acidity regulators on acrylamide and 5-hydroxymethylfurfural formation in French fries: The dual role of pH and acid radical ion

The influence of acidity regulators and buffers on the formation of acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) in French fries and the underlying mechanism were evaluated. Prior to frying, the potato strips were dipped in the corresponding acidity regulator solutions or buffers for 30 min at room temperature. The results showed that acids inhibited AA formation, but increased 5-HMF levels. The AA level decreased and 5-HMF level increased with decreasing pH of potato strips. Interestingly, increasing concentration of acid radical ions resulted in AA increase and 5-HMF decrease, which was opposite to the acidification effect of citric acid and acetic acid. Both pH and acid radical ion were important factors for AA and 5-HMF formation. Moreover, acidity regulators might impact AA formation by acting on the generation of methylglyoxal (MGO) and glyoxal (GO) and impact 5-HMF formation by acting on the generation of 3-deoxyglucosone (3-DG).

Catalytic conversion of cellulose and starch to furfural over zeolites

Conversion of cellulose and starch to furfural was investigated over four zeolites. The zeolites were characterized by X-ray diffraction, 27Al MAS NMR, IR spectra of pyridine adsorption and NH3 temperature-programmed desorption. The roles of acidity and pore structure of zeolites in conversion of cellulose and starch were discussed in detail. The results showed that Hβ zeolite with appropriate Brønsted acid sites, Lewis acid sites and pore structure was effective to produce furfural from cellulose and starch. HY zeolite could not catalyze cellulose reaction with high conversion because of its weak acidity. However, HY zeolite was effective to produce 5-hydroxymethylfurfural (HMF) from starch. H-mordenite and HZSM-5 zeolites with fewer Lewis acid sites could not cause the isomerization reaction from glucose to fructose. So, the further conversion of fructose to furfural or HMF was inhibited. The formation of HMF only depended on the acid properties of zeolites. The formation of furfural was not only determined by the acidity of zeolites, but also by their appropriate pore structure.

Effects of Sprouting and Fermentation on Free Asparagine and Reducing Sugars in Wheat, Einkorn, Oat, Rye, Barley, and Buckwheat and on Acrylamide and 5-Hydroxymethylfurfural Formation during Heating.

Usage of sprouted grains is an increasing trend in thermally processed foods. Sprouting alters the composition of sugars and amino acids, which are Maillard reaction precursors. Free asparagine, total free amino acids, and sugars were monitored during sprouting and yeast and sourdough fermentations. Acrylamide and 5-hydroxymethylfurfural (HMF) were analyzed in heated samples. The asparagine concentration decreased up to 40% after 24-36 h of sprouting, except for buckwheat, and then increased to the initial concentration after 48 h and several folds after 72 h. The increased amount of reducing sugars after sprouting caused higher acrylamide and HMF formation even if the asparagine concentration was lower. Acrylamide and HMF formation decreased after fermentation of sprouted wholemeal because sugars and asparagine were consumed by yeast. A pH drop of 3 units by sourdough fermentation decreased acrylamide formation but increased HMF formation. Results indicated that sprouted cereal products should be produced under controlled conditions to be used in heated foods.

Catalytic conversion of whey permeate into 5-hydroxymethylfurfural: Optimization and kinetic modeling approach

This work presents an efficient catalytic system for the valorization of whey permeate into 5-hydroxymethylfurfural (HMF). Lactose was studied as the model carbohydrate. The side products formed during the reaction were levulinic acid (LA), formic acid (FA), and humins. It was found that 0.25 mol/L of acetic acid and 0.21 mol/L of AlCl3·6H2O showed a synergistic effect on the HMF yield in γ-valerolactone and water as the binary solvent system. Three independent reaction parameters (reaction temperature, time, and AlCl3·6H2O concentration) were investigated to understand their effects on the formation of HMF, LA, and FA. The maximum HMF yield (59 mol%) for lactose was obtained at the optimum conditions (135 °C, 100 min, and 0.21 mol/L AlCl3·6H2O). The developed catalytic system was applied on different concentrations of whey permeates namely, whey permeate, ultrafiltered whey permeate, combined reverse osmosis-nanofiltered whey permeate after 30% evaporation, and whey permeate powder. Amongst all, the application of the developed catalytic system on whey permeate powder showed promising results, where 74 mol% HMF yield was obtained in a shorter reaction time (40 min) than lactose. The kinetic study demonstrated all the possible reaction pathways occurring during HMF formation for lactose and whey permeate powder. Key findingThe reaction kinetics for whey permeate powder discloses various possible reaction pathways for lactose to HMF conversion.

Reduction of 3-Deoxyglucosone by Epigallocatechin Gallate Results Partially from an Addition Reaction: The Possible Mechanism of Decreased 5-Hydroxymethylfurfural in Epigallocatechin Gallate-Treated Black Garlic.

5-Hydroxymethylfurfural (5-HMF) is a harmful substance generated during the processing of black garlic. Our previous research demonstrated that impregnation of black garlic with epigallocatechin gallate (EGCG) could reduce the formation of 5-HMF. However, there is still a lack of relevant research on the mechanism and structural identification of EGCG inhibiting the production of 5-HMF. In this study, an intermediate product of 5-HMF, 3-deoxyglucosone (3-DG), was found to be decreased in black garlic during the aging process, and impregnation with EGCG for 24 h further reduced the formation of 3-DG by approximately 60% in black garlic compared with that in the untreated control. The aging-mimicking reaction system of 3-DG + EGCG was employed to determine whether the reduction of 3-DG was the underlying mechanism of decreased 5-HMF formation in EGCG-treated black garlic. The results showed that EGCG accelerated the decrease of 3-DG and further attenuated 5-HMF formation, which may be caused by an additional reaction with 3-DG, as evidenced by LC-MS/MS analysis. In conclusion, this study provides new insights regarding the role of EGCG in blocking 5-HMF formation.

The O-factor: using the H-factor concept to predict the outcome of organosolv pretreatment

The H-factor, a parameter used extensively to analyze and predict the outcome of kraft pulping, is applied to organosolv pretreatment. The total solid yield after organosolv pretreatment fits well with the H-factor. The concept has been extended to apply to the individual biomass polymers using unique values for the activation energy for the depolymerization of the individual biomass polymers, giving the O-factor concept analogous to the P factor used for analyzing prehydrolysis kinetics. The results showed a linear relationship between ln(L0/L) and O-factor at an activation energy of 96 kJ/mol. The best linear fit for mannan and xylan degradation was obtained at O-factor activation energies of 104 kJ/mol and 142 kJ/mol, respectively, and the formation of furfural and 5-HMF gave a good linear fit using an O-factor activation energy of 150 kJ/mol. The O-factor is thus a useful concept for analyzing organosolv pretreatment when the temperature during pretreatment is not constant.

Ultrasonic-assisted leaching of glucose and fructose as an alternative mitigation technology of acrylamide and 5- hydroxymethylfurfural in potato chips

The effect of ultrasound (480 W, 40 kHz) on the leaching of reducing sugars during the water soaking of potatoes slices (60, 70 and 80 °C- 1, 8 and 15 min) was investigated to reduce the formation of acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) in potato chips.Ultrasound (US) influenced abruptly the reducing sugar leaching during the first 15 min, significantly increasing their extraction rate (glucose: 60%, fructose: 30%) at all evaluated temperatures. When potato slices were treated with US, the formation of AA (~95%) and 5-HMF (~96%) were reduced significantly after frying. Although AA content did not correlate with glucose and fructose concentrations, 5-HMF did (r2: 0.80 and 0.83, respectively), probably because reducing sugars are their main precursors. The AA and 5-HMF concentrations of potato chips presented good correlation coefficient (r2:0.76), suggesting the use of 5-hydroxymethylfurfural as an acrylamide indicator for potato chips.

Influence of Lewis acidity and CaCl2 on the direct transformation of glucose to 5-hydroxymethylfurfural

Nb-Zr oxides were evaluated for glucose dehydration to 5-hydroxymethylfurfural. A linear relationship was found between the amount of acid sites and niobium content. Pure Nb2O5 showed the highest acid concentration and surface area and both Brönsted and Lewis acid sites, whereas Zr-containing catalysts mostly showed Lewis acid sites. Thus, a correlation between the amount of acid sites and catalytic performance was demonstrated, in the absence of metal salt, being Nb2O5 the most active catalyst. However, the catalytic results obtained by the combination of CaCl2 and Zr-containing catalysts, which only showed Lewis acid sites, suggested the direct formation of HMF, without fructose formation, unlike that observed for Nb2O5, which possesses both Brönsted and Lewis acid sites. A HMF yield of 44% was attained by using Nb3Zr7 as acid catalyst and CaCl2 after 90 min at 175 ºC. These catalysts can be reused at least 3 catalytic runs without any pretreatment.

Kinetic study for ascorbic acid degradation, hydroxymethylfurfural and furfural formations in Orange juice

In this study, changes in ascorbic acid-(AA), hydroxymethylfurfural-(HMF) and furfural content of orange juice (OJ) were investigated during processing with different thermal treatments and storage conditions. According to the AA degradation kinetics; the half-lifes of thermally processed OJ at 70, 75, 80, 85 and 90 °C ranged between 666.5–1136.3 s. D-values for the same temperatures were calculated as 3774.7, 3337.1, 2914.7, 2646.6 and 2214s, respectively. z, Ea and Q10-values of AA were also calculated as 86.32 °C, 26.87 kJ mol−1, and 1.31; respectively. HMF formation kinetics showed that the doubling time of thermally processed OJ (70−90 °C) were determined between 42.0 and 77.0 s. D-values at those temperatures ranged from 139.6–255.8 s. z, Ea and Q10-values of HMF were also calculated as 75.98 °C, 31.34 kJ mol−1, and 1.35, respectively. For furfural formation kinetics, doubling time of thermally processed OJ at 70−90 °C was determined between 52.1–74.5 s. The D-values of furfural were calculated between 173.1–274.1 s at the same temperatures. z, Ea and Q10-values of furfural were also calculated as 100.21 °C, 24.98 kJ mol−1, and 1.26, respectively. The most obvious changes were determined during storage at 25 °C for the investigated compounds when compared to 4 °C. OJ samples processed at moderate temperatures performed better AA retention, and lower HMF and furfural formation was determined for those samples during shelf-life.

The complex dependence of non-enzymatic browning development on processing conditions in maize snacks

The complex dependence of non-enzymatic browning development on processing conditions was analyzed in the production of maize snacks. The influence of the amount of water added to maize flour, toasting time, and toasting temperature on final water contents, HMF formation and CIELAB color parameters was evaluated by Response Surface Methodology. While L* values decreased continuously with increasing toasting temperature, the variables a* and b* showed maximum values at intermediate studied ranges of temperature and water contents, which is related to the complex interactions of the variables water content and temperature. The formation of HMF, as a marker of non-enzymatic browning reactions, was favored by low water contents and its concentration correlated with lower L* and b* but higher a* values. The optimum levels of toasting time, toasting temperature, and water addition for minimizing HMF concentration at which the snacks presented adequate color characteristics were determined. Finally, correlations between L*, b* and HMF were mathematically established to predict heat damage using these fast and non-destructive indicators to assure adequate processing and storage conditions.

Effect of formulation and heat treatment on 5-hydroxymethylfurfural formation and quality parameters in dulce de leche

ABSTRACT This work assessed the effect of formulation and heat treatment on the formation of HMF, non-enzymatic browning and rheology of dulce de leche (DL). Laboratory scale trials were developed with different DL formulas: whole powdered milk, skimmed milk, and lactose-free skimmed milk, and added sucrose, subjected to different processing temperatures (110°C, 120°C, and 130°C). Additionally, an alternative formulation was designed in which half the sucrose was replaced by 50% tagatose. DL samples were compared with three commercial products in terms of water activity, soluble solids content, pH, colour, apparent viscosity, and HMF concentration. HMF formation in DL was mitigated (35%) in a lactose-free formulation by lowering the process temperature. Moreover, HMF formation was reduced up to 80% replacing sucrose by tagatose without affecting the quality parameters (pH, soluble solids, colour, and apparent viscosity). Decrease in processing temperature and the use of tagatose are viable alternatives for HMF mitigation in DL.

Selective glucose dehydration over novel metal phthalocyanine catalysts at low temperatures

In this report, promising carbon-based novel metal phthalocyanine catalysts were prepared and tested in glucose dehydration at low temperatures (90–130 °C) under atmospheric conditions. Most of the prepared phthalocyanines exhibited high conversions in dimethylsulfoxide (DMSO). A complete conversion of glucose was obtained over Aluminum phthalocyanine (AlPcCl) and Tin phthalocyanine (SnPcCl2) catalysts. AlPcCl also provided the highest HMF yield (53% in 3 h at 130 °C). Al3+ cations promoted the glucose conversion and Cl− anions played an active role in 5-Hydroxymethylfurfural (5-HMF) formation. Dimethylsulfoxide (DMSO) as a solvent, was also found effective with phthalocyanines for high 5-HMF yield by stabilizing its structure. Thus, the 5-HMF yield was observed high (53.0% at 130 °C for 3 h) over AlPcCl in DMSO. Kinetic studies showed that the optimum reaction temperature was 130 °C at 1/5 catalyst/glucose ratio for 3 h. Dehydration reactions, performed in the aqueous phase, exhibited higher fructose selectivities with AlPcCl catalyst.