5-Hydroxymethylfurfural content in foodstuffs determined by micellar electrokinetic chromatography

The Importance of Testing the Quality and Authenticity of Food Products: The Example of Honey

The aim of this study was to review methods of honey testing in the assessment of its quality and authenticity. The quality of honey, like other food products, is multidimensional. This quality can be assessed not only on the basis of the characteristics evaluated by the consumer during purchase and consumption, but also on the basis of various physicochemical parameters. A number of research methods are used to verify the quality of honeys and to confirm their authenticity. Obligatory methods of assessing the quality of honey are usually described in legal acts. On the other hand, other, non-normative methods of honey quality assessment are used worldwide; they can be used to determine not only the elementary chemical composition of individual types of honey, but also the biological activity of honey and its components. However, so far, there has been no systematization of these methods together with a discussion of problems encountered when determining the authenticity of honeys. Therefore, the aim of our study was to collect information on the methods of assessing the quality and authenticity of honeys, and to identify the problems that occur during this assessment. As a result, a tabular summary of various research methods was created.

Determination of 5-hydroxymethylfurfural using an electropolymerized molecularly imprinted polymer in combination with Salle

Coffee, a beverage with a complex chemical composition, is appreciated for the sensory experience of its taste and aroma. The compound 5-(hydroxymethyl)-2-furfural (HMF) is essential for sensory characterization of the beverage, and is also used in the traceability of its production. In this work, a procedure combining salting-out assisted liquid-liquid extraction (SALLE) and an electropolymerized molecularly imprinted polymer (e-MIP) was developed for the detection and quantification of HMF in coffee samples. The sample preparation step using SALLE employed a combination of acetonitrile and phosphate-buffered saline, in a proportion of 70:30 (ACN:PBS), with addition of 0.02 g of NaCl. The new sensor (e-MIP) was prepared by electropolymerization of p-aminobenzoic acid onto a glassy carbon electrode (GCE) using cyclic voltammetry (CV). Analytical determinations were performed by differential pulse voltammetry (DPV). The linear regression correlation coefficient (r²) for the response was 0.9986. The limits of detection and quantification were 0.372 mg L^-1 and 1.240 mg L^-1, respectively. The repeatability and reproducibility values obtained were 6 and 10%, respectively. The recoveries for three concentration levels were between 97 and 101%. Analyses of different coffee samples showed that the HMF concentrations varied from 261.0 ± 41.0 to 770.2 ± 55.9 mg kg^-1 in powdered coffee samples, and from 1510 ± 50 to 4445 ± 278 mg kg^-1 in instant coffee samples. The advantages of this procedure, compared to other methods described in the literature, are its simplicity, easy operation, good selectivity and sensitivity, low cost, and minimal use of organic solvents.

Effect of roasting conditions on cocoa bioactivity and gut microbiota modulation

Cocoa is a highly consumed food with beneficial effects on human health. Cocoa roasting has an important influence on its sensory and nutritional characteristics; therefore, roasting could also play a role in cocoa bioactivity. Thus, the aim of this paper is to unravel the effect of cocoa roasting conditions on its antioxidant capacity and modifications of gut microbiota after in vitro digestion-fermentation. HMF and furfural, chemical markers of non-enzymatic browning, were analyzed in unroasted and roasted cocoa powder at different temperatures, as well as different chocolates. The antioxidant capacity decreased with roasting, most probably due to the loss of phenolic compounds during heating. In the case of the evaluated chocolates, the antioxidant capacity was 2-3 times higher in the fermented fraction. On the other hand, HMF and furfural content increased during roasting due to increasing temperatures. Moreover, unroasted and roasted cocoa powder have different effects on gut microbial communities. Roasted cocoa favored butyrate production, whereas unroasted cocoa favored acetate and propionate production in a significant manner. In addition, unroasted and roasted cocoa produced significantly different gut microbial communities in terms of composition. Although many bacteria were affected, Veillonella and Faecalibacterium were some of the most discriminant ones; whereas the former is a propionate producer, the latter is a butyrate producer that has also been linked to positive effects on the inflammatory health of the gut and the immune system. Therefore, unroasted and roasted cocoa (regardless of the roasting temperature) promote different bacteria and a different SCFA production.

Caramel colors in terms of scientific research, with particular consideration of their toxicity

Caramel colors, the most common food additives in the world, are divided into four classes (IIV), marked with the symbols E150 a-d, respectively. Individual classes of caramel colors differ from each other in physico-chemical properties and the method of preparation, which affects the formation of various compounds that are important for the assessment of food safety A number of studies on all caramel classes of have been performed, including toxicokinetic, genotoxic, carcinogenic and reproductive and developmental toxicity studies, which have not shown harmful effects of these additives at doses not exceeding ADI. However, there is an increasing number of scientific reports of the possible toxic effects present in caramels of low-molecular compounds. Currently, three compounds are considered to be toxicologically important and resulting from the possible concentration in the final product: 5-HMF (present in all classes), 4(5)-MeI (present in caramel classes III and IV) or THI (present in caramel class III). 4(5)-MeI has a neurotoxic effect and was considered in 2011 as a possible human carcinogen (class 2B, according to IARC). In the case of THI, studies have confirmed its lymphopenic activity, probably secondary to its immunosuppressive effect. Consequently, in the 1980s, JECFA set acceptable levels 4(5)-MeI and THI, for the caramel classes in which these compounds may be present. The toxicity of 5-HMF has not been confirmed unequivocally, but studies have shown that this compound is not neutral to living organisms. Currently, most international organizations and scientific institutes recognize these additives as safe for consumers, but at the same time scientists emphasize the need for further research.

A New Enrichment Method for Quantification of 5-Hydroxymethylfurfural by Indirect Flame Atomic Absorption Spectrometry in Honey and Jam Samples

Background

Because of increasing amounts of 5-hydroxymethylfurfural (5-HMF) in processed foods and the complexity of the matrix, monitoring of trace 5-HMF requires accurate and reliable methods. Hence, an efficient sample pretreatment procedure is necessary for extraction and preconcentration of 5-HMF from the matrix.

Objective

In this study, a new and efficient sample preparation method utilizing ultrasound-assisted-cloud point extraction (UA-CPE), indirectly followed by flame atomic absorption spectrometry (FAAS), was introduced for the monitoring of trace amounts of 5-HMF in honey and jam samples.

Method

With this method, hydroxylamine was used as a derivatizing agent in the presence of Mn(II) and an anionic surfactant, SDS for extraction of 5-HMF at pH 9.0. For dispersing reagents in sample solution, low amounts of mixed surfactant, triton X-45 and SDS were mixed and fast-injected into the extraction media. A cloudy solution formed, and after reaction of 5-HMF with reagents, the cloudy solution was centrifuged. The extracted 5-HMF in the surfactant-rich phase was dissolved in acidic acetone and indirectly analyzed by FAAS.

Results

The method showed a detection limit of 1.27 μg/L in linear working range of 4–240 μg/L, good precision (2.3–6.5%), and recovery rates (93.5–97%) after preconcentration of 70-fold.

Conclusions

Within this study, an accurate and reliable method for the indirect quantification of 5-HMF in selected samples was successfully developed with a sensitivity improvement factor of 30.6.

Highlights

The figures of merit for the developed indirect method were appropriate. The applicability of the method for the analysis of 5-HMF in processed foods was excellent.

Hydroxymethylfurfural determination in cereal and insect bars by high-performance liquid chromatography-mass spectrometry employing a functionalized mesostructured silica as sorbent in solid-phase extraction

In this work a new method for the determination of 5-hydroxymethylfurfural (HMF) in cereal and insect bars has been developed and validated. The method consisted of a solid-liquid extraction (SLE) followed by a solid phase extraction (SPE), employing functionalized mesostructured silica as sorbent, and prior to high-performance liquid chromatography coupled to mass spectrometry analysis (HPLC-MS/MS). Mesostructured silica with a large pore (SBA-15-LP) functionalized with aminopropyl- groups (SBA-15-LP-NH₂), octyl- groups (SBA-15-LP-C8) and bifunctionalized with both organic ligands (SBA-15-LP-C8-NH₂) were prepared, characterized and tested for this purpose. The optimal conditions showed that the best extraction solvent was water acidified with HCl (pH 1.0) and the best material for SPE was SBA-15-LP-NH₂ (recoveries near 100%). Results were compared with other analogous commercial sorbent (Discovery® DSC-NH₂), evaluated under similar conditions, and SBA-15-LP-NH₂ sorbent showed better recoveries than the commercial one (62 ± 1%). The developed method was validated and good detection and quantification limits (MDL: 11 µg kg^-1and MQL: 38 µg kg^-1), good precision in terms of repeatability and within-laboratory reproducibility (RSD < 8%) and good accuracy (recoveries between 99-102%) were obtained. The method was successfully applied to the determination of HMF in different samples of cereals and insect bars. In all the samples analysed, high concentrations of HMF (ranging from 336 to 962 mg kg^-1) have been found.

Evaluation of 5-hydroxymethylfurfural content in market milk products

5-Hydroxymethylfurfural (5-HMF) is a cyclic aldehyde formed during non-enzymatic browning reactions. In milk, it is, on the one hand, a contaminant, on the other, a quality indicator. The objective of this study was to evaluate the content and selected factors affecting the concentration of 5-HMF in cows' milk and first infant milk. The content of 5-HMF in market milk varied widely, the average was 54.8 μg L^-1 (3.3-136.8). There was no significant difference in the concentration of this contaminant between UHT, HTST pasteurised and micro-filtered milk. It was also shown that the content of lipid components did not affect the concentration and kinetics of the 5-HMF formation in milk subjected to thermal treatment. Lactose-free milk was characterised by a level of this compound much higher than regular products. The 5-HMF average contents in powder cows' milk and first infant milk were respectively 642 and 2315 μg kg^-1.

Potential neurotoxicity of 5-hydroxymethylfurfural and its oligomers: widespread substances in carbohydrate-containing foods

5-Hydroxymethylfurfural (5-HMF) is present in numerous carbohydrate-containing consumer products and is readily converted into two oligomers (II and III) by acid-catalyzed transformations. Previous studies have demonstrated various undesirable effects of 5-HMF at relatively high concentrations. In this study, we demonstrate that 5-HMF and its two oligomers exert neurotoxic effects in vivo and in vitro. All three substances blocked the proliferation of PC12 and HT22 cells at the S or G2-M phase in dose- and time-dependent manners. In addition, [Ca²⁺]i and reactive oxygen species levels were both significantly increased by treatment with these substances at 100 μM, individually, compared with the control group. Although no motor and cognitive deficits are observed, 5-HMF and III can induce anxiety- and depression-like behavior in adolescent mice at administered doses of 0.15 mg kg^-1 and 1.5 mg kg^-1in vivo, which are close to or less than the reported 24 h dietary intake of 5-HMF in humans. Together, our findings suggest the need for close monitoring of the content of these substances in food, as well as the need for studies on the effects of long-term exposure to them.

Simultaneous Determination of Acrylamide and Hydroxymethylfurfural in Extruded Products by LC-MS/MS Method

The aim of this study was to develop a liquid chromatography/tandem mass spectrometry LC-MS/MS method for the simultaneous determination of acrylamide and hydroxymethylfurfural (HMF) in corn snack products enriched with food industry by-products: brewer's spent grain (BSG), sugar beet pulp (SBP) and apple pomace (AP). Development of the method included the study of different sources for ionization, different mobile phases, different extraction conditions as well as different methods of sample preparation. Finally, the single LC-MS/MS method was developed for the analysis of both analytes in one step with a duration of 20 min using a simple single-step extraction. The method with apparent recoveries of 91.4 and 90.4 for acrylamide and HMF, respectively, was applied for the analysis of non-extruded and extruded samples. The obtained results shown that the acrylamide content was Collapse

Key Words

• LC-MS/MS method
• acrylamide
• extruded snack products
• hydroxymethylfurfural

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MESH Headings

• Acrylamide/analysis
• Beta vulgaris/chemistry
• Chromatography, High Pressure Liquid
• Food Contamination/analysis
• Food Industry
• Furaldehyde/analogs & derivatives
• Furaldehyde/analysis
• Malus/chemistry
• Tandem Mass Spectrometry/methods
• Zea mays/chemistry

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Grants

• 1321 Hrvatska Zaklada za Znanost

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Affiliation(s)

Antun Jozinović Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Bojan Šarkanj Department of Food Technology, University Centre Koprivnica, University North, Trg dr. Žarka Dolinara 1, 48000 Koprivnica, Croatia.
Đurđica Ačkar Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Jelena Panak Balentić Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Domagoj Šubarić Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia.
Tanja Cvetković Research and Development, Podravka d.d., Ante Starčevića 32, 48000 Koprivnica, Croatia.
Jasmina Ranilović Research and Development, Podravka d.d., Ante Starčevića 32, 48000 Koprivnica, Croatia.
Sunčica Guberac Faculty of Agrobiotechnical Sciences Osijek, Josip Juraj Strossmayer University of Osijek, Vladimira Preloga 1, Osijek 31000, Croatia.
Jurislav Babić Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.

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Occurrence of Furosine and Hydroxymethylfurfural in Breakfast Cereals. Evolution of the Spanish Market from 2006 to 2018

The demand for healthier products has led the breakfast cereal sector to develop new formulations to improve the nutritional profile of breakfast cereals; however, the increase in chemical risks should also be evaluated. Amadori compounds and 5-hydroxymethylfurfural (HMF) are Maillard reaction products applied as heat damage indices in breakfast cereals. Furosine (a synthetic amino acid formed by acid hydrolysis of Amadori compounds) is linked to the loss of protein quality, while HMF has exhibited toxicological effects in cells and animals. Furosine and HMF content was evaluated in Spanish breakfast cereals whereas the effect of protein, fibre, and sugar content, the type of grain, the presence of honey, and the manufacturing process were discussed, as well as compared with a previous prospective study. The average furosine and HMF contents were 182 mg/kg and 21.7 mg/kg, respectively. Protein and fibre content were directly related to the furosine content, whereas sugar level, honey addition, and the manufacturing process affected the content of HMF. Occurrence of furosine and HMF decreased nearly 40% in a decade (2006-2018). These findings are relevant in terms of nutritional score, since lysine availability is preserved, but also from a toxicological point of view, due to the decreased daily exposure to both compounds, which dropped 30%.

Simultaneous Determination of Acrylamide and 5-Hydroxymethylfurfural in Heat-Processed Foods Employing Enhanced Matrix Removal-Lipid as a New Dispersive Solid-Phase Extraction Sorbent Followed by Liquid Chromatography-Tandem Mass Spectrometry

The goal of this study was to develop a method for simultaneous determination of acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) in heat-processed foods by liquid chromatography-tandem mass spectrometry analysis. Several cleanup methods for the quick, easy, cheap, effective, rugged, and safe (QuEChERS) protocol were investigated and compared: (a) dispersive solid-phase extraction (d-SPE) with Enhanced Matrix Removal-Lipid (EMR-Lipid), (b) d-SPE with primary secondary amine, (c) without the cleanup step, and (d) cleanup with n-hexane. It is the first time that EMR-Lipid sorbent has been used as a d-SPE material to detect AA and 5-HMF in heat-processed foods, and among the four cleanup methods, the EMR-Lipid method provided the best cleanup of co-extracted matrix interferences and the highest extraction efficiency. Validation experiments were carried out for the method using EMR-Lipid as the d-SPE sorbent. Excellent linearity ( R² > 0.999) was achieved, and the limits of detection (LODs) of AA and 5-HMF were 2.5 and 12.5 μg/kg, respectively. The recoveries of AA and 5-HMF levels obtained were in the ranges of 87.3-103.3 and 83.2-104.3%, with precision [relative standard deviations (RSDs)] of 1.2-6.8 and 1.4-7.4% ( n = 3), respectively. The method is accurate and reliable and was successfully applied to analyze the AA and 5-HMF in eight categories of Chinese heat-processed foods.

HPLC-DAD method development and validation for the quantification of hydroxymethylfurfural in corn chips by means of response surface optimisation

In recent years, there has been an increased concern about the presence of toxic compounds derived from the Maillard reaction produced during food cooking at high temperatures. The main toxic compounds derived from this reaction are acrylamide and hydroxymethylfurfural (HMF). The majority of analytical methods require sample treatments using solvents which are highly polluting for the environment. The difficulty of quantifying HMF in complex fried food matrices encourages the development of new analytical methods. This paper provides a rapid, sensitive and environmentally-friendly analytical method for the quantification of HMF in corn chips using HPLC-DAD. Chromatographic separation resulted in a baseline separation for HMF in 3.7 min. Sample treatment for corn chip samples first involved a leaching process using water and afterwards a solid-phase extraction (SPE) using HLB-Oasis polymeric cartridges. Sample treatment optimisation was carried out by means of Box-Behnken fractional factorial design and Response Surface Methodolog y to examine the effects of four variables (sample weight, pH, sonication time and elution volume) on HMF extraction from corn chips. The SPE-HPLC-DAD method was validated. The limits of detection and quantification were 0.82 and 2.20 mg kg^-1, respectively. Method precision was evaluated in terms of repeatability and reproducibility as relative standard deviations (RSDs) using three concentration levels. For repeatability, RSD values were 6.9, 3.6 and 2.0%; and for reproducibility 18.8, 7.9 and 2.9%. For a ruggedness study the Yuden test was applied and the result demonstrated the method as robust. The method was successfully applied to different corn chip samples.

A validated fast difference spectrophotometric method for 5-hydroxymethyl-2-furfural (HMF) determination in corn syrups

Corn syrups, important ingredients used in food and beverage industries, often contain high levels of 5-hydroxymethyl-2-furfural (HMF), a toxic contaminant. In this work, an in house validation of a difference spectrophotometric method for HMF analysis in corn syrups was developed using sophisticated statistical tools by the first time. The methodology showed excellent analytical performance with good selectivity, linearity (R²=99.9%, r>0.99), accuracy and low limits (LOD=0.10mgL^-1 and LOQ=0.34mgL^-1). An excellent precision was confirmed by repeatability (RSD (%)=0.30) and intermediate precision (RSD (%)=0.36) estimates and by Horrat value (0.07). A detailed study of method precision using a nested design demonstrated that variation sources such as instruments, operators and time did not interfere in the variability of results within laboratory and consequently in its intermediate precision. The developed method is environmentally friendly, fast, cheap and easy to implement resulting in an attractive alternative for corn syrups quality control in industries and official laboratories.

Mitigation strategies of acrylamide, furans, heterocyclic amines and browning during the Maillard reaction in foods

The Maillard reaction (MR) occurs widely during food manufacture and storage, through controlled or uncontrolled pathways. Its consequences are ambiguous depending on the nature and processing of the food products. The MR is often used by food manufacturer to develop appealing aromas, colour or texture in food products (cereal based food, coffee, meat…). However, despite some positive aspects, the MR could decrease the nutritional value of food, generate potentially harmful compounds (e.g. acrylamide, furans, heterocyclic amines) or modify aroma or colour although it is not desired (milk, fruit juice). This paper presents a review of the different solutions available to control or moderate the MR in various food products from preventive to removal methods. A brief reminder of the role and influence of the MR on food quality and safety is also provided.

Non-enzymatic browning in citrus juice: chemical markers, their detection and ways to improve product quality

Citrus juices are widely consumed due to their nutritional benefits and variety of pharmacological properties. Non-enzymatic browning (NEB) is one of the most important chemical reactions responsible for quality and color changes during the heating or prolonged storage of citrus products. The present review covers various aspects of NEB in citrus juice viz. chemistry of NEB, identifiable markers of NEB, analytical methods to identify NEB markers and ways to improve the quality of citrus juice. 2,5-Dimethyl-4-hydroxy-3(2H)-furanone (DMHF) is one of the promising marker formed during browning process with number of analytical methods reported for its analysis; therefore it can be used as an indicator for NEB process. Amongst analytical methods reported, RP-HPLC is more sensitive and accurate method, which can be used as analytical tool. NEB can be prevented by removal of amino acids/ proteins (via ion exchange treatment) or by targeting NEB reactions (e.g. blockage of furfural/ HMF by sulphiting agent).

Kinetics of browning, phenolics, and 5-hydroxymethylfurfural in commercial sparkling wines

We analyzed the degree of browning (absorbance at 420 nm), the phenolics, and the 5-hydroxymethylfurfural (5-HMF) content in six sparkling wines series kept at three temperatures (4, 16, and 20 °C) for over 2 years. Caffeic acid, trans-coutaric acid, p-coumaric acid, and 5-HMF were the compounds with the greatest correlation with browning and time. 5-HMF was the only compound that evolved linearly at all temperatures. We propose that 5-HMF is a better time-temperature marker than the A₄₂₀ parameter or phenolics, because it shows higher linearity with time at all temperatures, is more sensitive to temperature changes, and has lower variability. The kinetics of 5-HMF was studied showing a zero-order behavior. We propose mathematical models that wineries can use to predict the browning shelf life of their sparkling wines as a function of the storage time and temperature.

1,2-dicarbonyl compounds in commonly consumed foods

1,2-Dicarbonyl compounds, formed from carbohydrates during thermal processing in the course of caramelization and Maillard reactions, are intensively discussed as precursors for advanced glycation endproducts in foods and in vivo. To obtain information about the uptake of individual compounds with commonly consumed foods, a comprehensive analysis of the content of 3-deoxyglucosone (3-DG), 3-deoxygalactosone (3-DGal), and methylglyoxal (MGO) together with 5-hydroxymethylfurfural (HMF) in 173 food items like bakery products, pasta, nonalcoholic and alcoholic beverages, sweet spreads, and condiments was performed. Following suitable cleanup procedures, 1,2-dicarbonyl compounds were quantitated after derivatization with o-phenylenediamine via RP-HPLC with UV detection. 3-DG proved to be the predominant 1,2-dicarbonyl compound with concentrations up to 410 mg/L in fruit juices, 2622 mg/L in balsamic vinegars, and 385 mg/kg in cookies, thus exceeding the corresponding concentrations of HMF. 3-DGal was found to be of relevance in many foods even in the absence of galactose. MGO was only of minor quantitative importance in all foods studied, except for manuka honey. Dietary intake was estimated to range between 20 and 160 mg/day for 3-DG and 5 and 20 mg/day for MGO, respectively.

Micellar electrokinetic chromatography method for the simultaneous determination of furanic compounds in honey and vegetable oils

A simple micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of 2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF), 5-hydroxymethylfurfural (5-HMF), 2-furoic acid (2-FA) and 3-furoic acid (3-FA) in honey and vegetable oils is described. Parameters affecting the separation such as pH, buffer and surfactant concentrations, applied voltage, capillary temperature, injection time and capillary length were studied and optimized. The separation was carried out in normal polarity mode at 20 °C, 22 kV and using hydrodynamic injection (17 s). The separation was achieved in a bare fused-silica capillary (46 cm × 50 μm i.d.) with a background electrolyte of 75 mM phosphoric acid (pH 7.3), containing 200 mM of sodium dodecyl sulphate (SDS). The detection wavelengths were at 200 nm (2-FA and 3-FA) and 280 nm (2-F, 3-F, 5-MF, 5-HMF). The furfurals were well separated in less than 20 min. The method was validated in terms of linearity, limit of detection and quantitation, precision and recoveries. Calibration curves of the six furfurals were well correlated (r(2)>0.991) within the range 1-25 μg mL(-1). Relative standard deviations of intra- and inter-day migration times and corrected peak areas ≤9.96% were achieved. The limit of detection (signal:noise, 3) was 0.33-0.70 μg mL(-1) whereas the limit of quantitation (signal:noise, 10) was 1.00-2.12 μg mL(-1). The method was applied to the determination of furanic compounds in honeys and vegetable oils (palm, walnut, grape seed and rapeseed). The effects of thermal treatment and gamma irradiation on the formation of the furanic compounds in honey were also investigated.