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This study was intended to evaluate the quality parameters of 58 Apis mellifera honey samples, from different regions in the Sultanate of Oman. Physicochemical analyses were carried out and examined according to the Gulf Standardization Organization (GSO). The results revealed that 64.4% of the samples were failing to meet the GSO standards due to acidity, hydroxyl methyl furfural (HMF), diastase, sucrose, and glucose & fructose. Acidity and HMF were above the limits in 30% and 29% of the failed samples respectively, where diastase and total glucose & fructose were below the limits in 25% and 5% respectively. Sucrose was above the limits in 11% of the failed samples. The unconformity of the analyzed honey samples to GSO standards could be due to stage of harvesting, process and storage conditions. Therefore, it’s important to reconsider the whole process of honey production in Oman in order to improve the technology and honey quality. [ABSTRACT FROM AUTHOR]

Honey is a food of high importance due to its nutritional value. The effect of late harvest and pollen composition on honey quality and antimicrobial activity was studied. Different physicochemical parameters were determined as quality indicators. The HMF content, diastase activity, sugar content, antimicrobial activity, and hydrogen peroxide content were selected in current work as the crucial parameters for evaluation. The results proved that the late harvested honey sample showed a vast number of pollens from different blossom periods. The hydrogen peroxide content and antimicrobial activity of late harvested honey was significantly increased (proved by t -test), whereas the honey seems to be affected significantly from weather conditions since the HMF content was also increased. The diastase activity was proved to be lower than the respective in fresh honey, whereas no difference was observed on the sugar content. Finally, the effect of origin and processing in late harvested honey was discussed. [ABSTRACT FROM AUTHOR]

Ammonia caramels are the most common antioxidant colour agent used in bakery formulations, although their high sugars content. An alternative could be coffee melanoidins, which are brown coloured compounds with antioxidant properties, readily available from instant coffee. However, high caffeine content is limiting its direct application. To evaluate the possibility of obtaining coloured melanoidin-rich, sugars- and caffeine-poor fractions from instant coffee, in this work, simple procedures based on their ethanol insolubility (fraction EtPp) or retention by ultrafiltration (fraction HWSn) were exploited. Melanoidins incorporation into biscuits formulation (amounts of 1, 5 and 10% w/w related to flour content) resulted in acceptable coloured products with higher antioxidant activity. The biscuits supplemented with 1% EtPp or HWSn had a low caffeine content. The caffeine of one espresso coffee was equivalent to 130 biscuits containing EtPp and 31 biscuits containing HWSn. Besides, both fractions did not promote extra formation of acrylamide or 5-hydroxymethylfurfural during baking. [ABSTRACT FROM AUTHOR]

A fully validated approach for the determination of diastase activity and hydroxymethylfurfural content in honeys were presented in accordance with the official methods. Methods were performed in real honey sample analysis and due to the vast number of collected data sets reliable conclusions about the correlation between the composition and the quality criteria were exported. The limits of detection and quantification were calculated. Accuracy, precision and uncertainty were estimated for the first time in the kinetic and spectrometric techniques using the certified reference material and the determined values were in good accordance with the certified values. PCA and cluster analysis were performed in order to examine the correlation among the artificial feeding of honeybees with carbohydrate supplements and the chemical composition and properties of the honey. Diastase activity, sucrose content and hydroxymethylfurfural content were easily differentiated and these parameters were used for indication of the adulteration of the honey. [ABSTRACT FROM AUTHOR]

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 (R 2 = 99.9%, r > 0.99), accuracy and low limits (LOD = 0.10 mg L −1 and LOQ = 0.34 mg L −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. [ABSTRACT FROM AUTHOR]

Fifty-eight samples of commercial Colombian coffee with different characteristics (soluble, ground, decaffeinated, etc) were evaluated for antioxidant capacity (AC) (ABTS and FRAP), total soluble phenolics (TP), browning index (BI), color parameters (L ∗ , a ∗ , b ∗ , c ∗ and h ∗ ), HMF and furfural. The AC in Colombian coffees was very varied (164–1000, 100.8–885.9 μmol of Trolox equiv/g and 12.5–127 mg gallic acid equiv/g, respectively for ABTS, FRAP and TP). AC, TP, BI, color, HMF and furfural values were higher ( p < 0.05) in soluble coffees than in ground ones, showing the lyophilized samples which showed the highest average values. Significant lineal correlations ( p < 0.05) were found between AC and color parameters, BI, HMF. No significant ( p < 0.05) differences in the AC between the different types of coffee were found. This work confirms the direct relationship between the rate of non-enzymatic browning and antioxidant capacity. [ABSTRACT FROM AUTHOR]

• Humidification of the crust and dryness of the crumb with water migration. • Decrease of crust and crumb lightness during storage regardless oil type. • Migration of HMF and furfural from the crumb to the crust during the storage. • Increase of the HMF and furfural accumulation with the increase of lipids unsaturation. • Positive correlation between HMF and furfural migration and the storage period. This work aimed at studying the influence of formulation and storage on the formation of Maillard compounds called 5-hydroxymethylfurfural (HMF) and furfural in pound cakes formulated with rapeseed oil (RO) and palm oil (PO). A progressive humidification of the crust and a dryness of the crumb were observed during storage. Lightness (L*) decreased for both PO and RO pound cakes in crumb as well as crust. The accumulation of HMF was found to be higher in the crust (2.21–38.5 mg kg−1) in comparison with the crumb (0.78 to 10.29 mg kg−1). Similar results were found for furfural where the concentration range was between 0.98 and 5.67 mg kg−1 in the crumb while between 2.1 and 38.39 mg kg−1 in the crust. Thus, the formation of HMF and furfural depended on formulation. The PLS-DA showed a positive correlation between the kinetic of HMF and furfural migration and the storage period. [ABSTRACT FROM AUTHOR]

Chlorogenic acid (CGA) is a phenolic acid that ubiquitously exists in fruits. This work aims to investigate whether and how CGA influences HMF formation during heating fructose alone, or with an amino acid. The results showed that that CGA increased 5-hydroxymethylfurfural (HMF) formation. At pH 5.5 and 7.0, the addition of 5.0 μmol/ml CGA increased HMF formation by 49.4% and 25.2%, respectively when heating fructose alone, and by 9.0% and 16.7%, respectively when heating fructose with aspartic acid. CGA significantly increased HMF formation by promoting 3-deoxosone formation, and its conversion to HMF by inhibiting HMF elimination, especially in the Maillard reaction system. A comparison of the catalytic capacity of CGA with its six analogous compounds showed that both its di-hydroxyphenyl and carboxyl groups function in increasing HMF formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • HMF is a quality marker in food. • It is formed in the Maillard reaction and caramelization process. • HMF indicates food non-conformities and processing efficiency. • Novel spectrometric, chromatographic, and electroanalytical methods for HMF determination are critically discussed. The thermal processing, storage, and transportation of foodstuffs (e.g., fruit juices, coffee, honey, and vinegar) generate 5-hydroxymethylfurfural (HMF). The food industry uses this compound as a quality marker, thus increasing the demand for fast and reliable analytical methods for its determination. This review focuses on the formation of HMF in food, its desirable and toxic effects, and recent advances in analytical methods for its determination in foodstuffs. The advantages and limitations of these analytical approaches are discussed relative to the main analytical features. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different honeys are produced in different parts of Turkey. [•] The known honeys are pine, citrus and chestnut honey. [•] Various flower honeys are produced in these and other regions. [•] Composition of honey changes according to plant source of nectar. [Copyright &y& Elsevier]

• One year study in honey to estimate the best procedure to delay crystallization. • Six different pretreatment procedures investigated. • Time differentiation of the selected quality parameters of honey were determined. • Storage of honey at −18 °C extended the shelf-life of honey. The current study investigated the effect of different thermal and non-thermal procedures for the estimation of the optimum conditions of treatment of different honey types (erica, cotton, thyme, eucalyptus and pine honey) to avoid or delay crystallization without losing the nutritional benefits of honey. Different physicochemical parameters, such as pollen analysis, hydroxymethylfurfural (HMF), diastase activity, acidity, and total phenolic compounds were used as quality indicators. The different treatment procedures were evaluated in different honey types and in different time periods. It was proved that to achieve a non-crystallised product that lasts over a year, samples must be heated at 72 oC or stored at −18 °C. However, only by storing samples at −18 °C kept the nutritional benefits of honey and provide similar results with the fresh unheated samples. All procedures were examined in a long-term period (one year) in order to have a complete and accurate result. [ABSTRACT FROM AUTHOR]

Highlights: [•] HMF occur during acid hydrolysation step of certain classical methods from some of food components. [•] In the traditional analysis method, amount of HMF increases with decreasing of sample amount. [•] Acid hydrolysis stage do not desorbed the HMF from protein. [•] In classical method, level of HMF is detected more than actual value depending on the food content. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optimisation of an efficient method for extraction of HMF and furfural from cakes. [•] Oven type and baking time influenced HMF content, moisture and volatile profile. [•] Cakes baked in a traditional oven presented the highest HMF and furfural contents. [•] Similar volatile profiles were obtained in cakes baked in traditional and steam ovens. [•] Steam oven cakes presented low HMF and furfural, high moisture and aroma. [Copyright &y& Elsevier]

Highlights: [•] The effect of thermal processing on the formation of HMF in honey was studied. [•] Microwave field, greatly accelerates the formation of HMF in honey. [•] Heat treatment did not significantly affect the antioxidant properties of honey. [ABSTRACT FROM AUTHOR]

Abstract: Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75mM phosphate buffer solution at pH 8.0 containing 100mM sodium dodecylsulphate was used as background electrolyte (BGE), and the separation was performed by applying +25kV in a 50μm I.D. uncoated fused-silica capillary. Good linearity over the range 2.5–250mgkg−1 (r 2 ⩾0.999) and run-to-run and day-to-day precisions at low and medium concentration levels were obtained. Sample limit of detection (0.7mgkg−1) and limit of quantification (2.5mgkg−1) were established by preparing the standards in blank matrix. The procedure was validated by comparing the results with those obtained with liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Levels of HMF in 45 different foodstuffs such as breakfast cereals, toasts, honey, orange juice, apple juice, jam, coffee, chocolate and biscuits were determined. [Copyright &y& Elsevier]

Abstract: A liquid chromatographic method with UV detection was developed to analyse 5-hydroxymethyl-2-furfural and its main metabolite 5-hydroxymethyl-2-furoic acid in urine. For the analysis on a reversed phase column was used with 5% methanol in water and 5mM tetramethylammoniumhydrogen sulphate as ion-pair reagent as eluent. The detection was done at the UV absorption maximum of HMFA at 255nm. The limit of quantification for HMFA was 7mg/L with a recovery of 89%. For sample preparation the urine was centrifuged and the supernatant diluted with water. Three hundred samples of human urine were analysed. The concentration of HMFA was in the range of 0–100mg/L with most of the samples around 10mg/L. [Copyright &y& Elsevier]

Abstract: The present study was undertaken to determine the physico-chemical parameters of honey samples obtained from retailers in Marmara Region (Site 1) and East Anatolia (Site 2) of Turkey. The 70 samples were analysed for parameters including moisture, total acidity, diastase activity, hydroxymethylfurfural (HMF), invert sugar, sucrose, ash, commercial glucose and starch. 10 of 70 (14.3%) honey samples were of unacceptable quality based on recommended criteria of moisture (3 of 70, 4.29%), diastase activity (3 of 70, 4.29%), HMF (2 of 70, 2.86%), invert sugar (4 of 70, 5.71%) and sucrose (2 of 70, 2.86%) by Turkish Food Codex and European Commission Regulation. The results of study indicated that 85.7% of honey samples were at good quality. It is important that the essential precautions should be taken to ensure standardisation and rationalisation of beekeeping techniques, manufacturing procedures and storing processes to improve honey quality. [Copyright &y& Elsevier]

Abstract: The study concerns the interactions between (+)-catechin and a representative oak wood aldehyde (5-(hydroxymethyl)furfuraldehyde for furanic aldehydes and vanillin for phenolic aldehydes) in a wine-like model solution in presence or not of SO2. The formed condensation products were characterised by LC/MS, LC/ESI/MS n , and ESI/HR/MS and we studied the effect of SO2 on these condensation reactions. [Copyright &y& Elsevier]

Abstract: Fresh apple juice was heated at 95°C for 30 and 60min, and then stored for 6 days for obtaining different extent of non-enzymatic browning. Front-face fluorescence excitation–emission-matrix (EEM) with excitation at 355 and 400nm and emission ranges of 385–600, and 430–600nm was used to measure the juice samples. The sign test pointed out an enhanced sensitivity of EEM compared to commonly used browning indicators, such as non-enzymatic browning index (NEBI), color readings in L ∗ a ∗ b ∗ space, and the concentration of 5-hydroxymethylfurfural (HMF). Using the fluorescence data, the correctness of classifications of fresh juice, heated juice, and stored juice were >85%. Multivariate analyses were applied to study the relations of fluorescence emission spectra and common indicators. For predicting NEBI, b ∗, and HMF, the correlation coefficients were >0.80. Resulting, the spectroscopic analyses of fluorescent neoformed products such as HMF provide a feasible approach to monitor non-enzymatic browning of juice. [Copyright &y& Elsevier]

Abstract: Micronutrients were determined in bottled tomato pulp stored at room temperature (20.0±1.8°C) for 0, 60, 120 and 180 days. After 180 days, lycopene content had undergone no significant change (p >0.05); ascorbic, malic and citric acid levels had fallen significantly (p <0.001); and there were significant increases in β-carotene level (p <0.001) and total phenolics concentration (p <0.01). The fall in organic acid levels correlated well with the increase in 5-hydroxymethyl-2-furfural (HMF) (r 2 >0.80). [Copyright &y& Elsevier]

Abstract: Experiments were conducted to determine if the contents of phenolics and browning reaction products and antioxidant activity of raisin extracts were closely dependent on the extraction solvent. Enhanced extraction yields were obtained from solvent containing higher water concentrations. However, total phenolic content (TPC) was highest for extracts obtained from solvent to water ratios of 60:40 (v/v), whereby the extract obtained from ethanol:water (60:40, v/v) had the highest TPC of 375mg gallic acid equivalents (GAE)/100g extract. HMF content was highest in extracts obtained from 60% solvent, regardless of solvent type. The extract obtained from 60% methanol had the highest HMF content at 199μg/g extract. Although the 60% solvents provided extract with high antioxidant components, the antioxidant activity of raisin extracts obtained from 80:20 (v/v) solvent/water was significantly higher than other raisin extracts obtained from different solvent concentrations. Phenolic acids, HMF, and low-molecular-weight flavonoids were responsible for the antioxidant activity, but not the high-molecular-weight flavonoids. [Copyright &y& Elsevier]

Abstract: The effects of dough formula and baking conditions on the formations of acrylamide and hydroxymethylfurfural (HMF) were studied in a cookie model system. Increasing the sugar concentration in the dough formula increased acrylamide formation during baking at 205°C for 11min. The effect of sugar on acrylamide formation was more pronounced for glucose than for sucrose, expectedly. Addition of citric acid into dough formula comprising sucrose increased the susceptibility of acrylamide formation, while it decreased acrylamide formation in the dough formula comprising glucose. Decreasing the pH of dough formula increased the tendency to surface browning and the formation of hydroxymethylfurfural in cookies during baking. The results suggest that a cookie with acceptable texture and colour, but having less than 150ng/g of acrylamide, can be manufactured by lowering the baking temperature and avoiding reducing sugars in the recipe. [Copyright &y& Elsevier]

Abstract: The influence of the type of sugar and baking temperature on sugar degradation, hydroxymethylfurfural (HMF) formation and browning was studied in model cookies. The baking process was characterised by the temperature in the cookie and the water content and activity. A reference browning was selected to compare the differently processed cookies. The accumulation of HMF was modelled at three temperatures for three formulas (sucrose (S-CK), glucose (G-CK) or fructose (F-CK)). HMF started to accumulate at a w between 0.5 and 0.7 depending on the temperature and followed a first order kinetic, highly dependent on the baking temperature and type of sugar. Cookies baked at 200°C accumulated 10–100 times less HMF than those baked at higher temperatures. Below 250°C, S-CK produced less HMF than G- or F-CK, but the inverse was observed at 300°C. By simultaneously modelling the kinetics of browning development and HMF formation, rapid comparison of the heat impact on cookies with different formulation and baking process is possible. [Copyright &y& Elsevier]

Abstract: White and red grape juices and their concentrates were subjected to thermal treatments at different temperatures ranging from 50 to 70°C at different times. 5-Hydroxymethylfurfural (5-HMF) and fluorescence relative index (FLRI) were measured. Response surface methodology (RSM) was applied to determine the effect of temperature and time on the HMF and FLRI formation at the different Brix (bx) degrees. An increase in temperature (from 50 to 70°C) and time (from 12 to 192h) for 15°, 45° and 65° Brix degrees was associated with an increase in HMF and FLRI development of white and red grape juices. HMF formation was higher in white grape juice and concentrates than in red ones. Optimum conditions were confirmed and these fitted the experimental data well. Thus, regression equations can be used to estimate HMF and FLRI values at various Brix degrees for white and red grape juices and concentrates. [Copyright &y& Elsevier]

Abstract: Spaghetti was prepared by replacing semolina with different amounts of lupin protein, in order to increase the protein content. A detailed investigation of the rheological properties of the dough and the cooking quality of pasta was performed in comparison to standard semolina spaghetti. Moreover, the effect of the addition of lupin protein on non-enzymatic browning was evaluated by measuring ε-furoylmethyllysine (furosine) and 5-hydroxymethyl-2-furancarboxaldehyde (HMF), which are considered useful indices of semolina quality and pasta processing conditions. Dried spaghetti fortified with 5% of lupin protein isolate has a colour and rheological features comparable with the semolina sample and also the behaviour during cooking results to be satisfactory. As far as the thermal damage is concerned, the furosine values of fortified spaghetti differ only marginally from standard pasta and the percentage lysine loss is quite small (ranging from 12.1% to 15.7%). [Copyright &y& Elsevier]

The roles of oil, hexanal and sucrose were investigated in colour development and HMF formation during roasting of hazelnuts. The highest HMF levels and the deepest browning extension were in crushed hazelnuts and the lowest HMF and browning were in defatted or partially defatted samples. The addition of hexanal, at 175 °C, increased the HMF level. This was particularly evident in samples with sucrose. Moreover samples totally reintegrated in oil did not reach (after roasting) the same HMF level and colour as the corresponding crushed samples. [Copyright &y& Elsevier]

[Display omitted] • Thermal treatment of non-wheat flours resulted in acrylamide and HMF formation. • Dry heating causes excessive acrylamide content in the flours. • Hydrothermal treatment has a negligible effect on acrylamide presence. • Acrylamide in dry heated flours is strongly correlated with asparagine and glutamine. • Acrylamide in respective breads exceeded the benchmark level of 100 µg/kg. This is the first report about the influence of dry and wet heat treatment on acrylamide content in flours and, subsequently, in breads. It was shown that during production of some breads acrylamide content decreases. Dry heating of non-wheat flour resulted in acrylamide in flours of sorghum (160 µg/kg); millet (447 µg/kg); barley (516 µg/kg); triticale (868 µg/kg); rye (1833 µg/kg); oat (1951 µg/kg). Hydrothermal heating had a negligible impact on acrylamide formation. In breads made from flour blends consisted of 70% of dry thermally and 30% of hydrothermally treated flours of millet, sorghum, oat, and rye, respectively, acrylamide was detected in the range from 105 to 312 µg/kg. 5-hydroxymethylfurfural probably contributing to acrylamide formation in bread was detected in the range from 2.0 mg/kg to 44.3 mg/kg in dry heated flours; in hydrothermally treated flours was below LOQ (1.7 mg/kg); in breads was between 3.3 and 8.0 mg/kg. [ABSTRACT FROM AUTHOR]

• The baking in N 2 and CO 2 atmosphere decreased acrylamide as 50% • The baking in SO 2 atmosphere blocked acrylamide formation in bread. • The SO 2 atmosphere reduced HMF by 13% compared to control. • The acrylamide content was positively correlated with flavour of bread. The baking in N 2 and CO 2 atmosphere decreased by 50% the acrylamide, while this level was 99% in SO 2. The highest acrylamide content was detected in the control sample as 39.03 µg/kg. Additionally, the lowest HMF content was determined in S-bread as 14.85 mg/kg. The baking atmosphere has a significant impact on L* and a* colour values of bread. The highest L* value was measured in S-bread as 71.2, whereas it was the lowest in the control sample as 49.1. According to the Pearson results, acrylamide showed a negative correlation between L* value. However, no correlation was detected between colour values and HMF. Acrylamide had a positive correlation with flavour, although it did not affect the taste features of bread. No correlation between HMF and sensory properties was determined. The result of the study suggested that inert or inhibitor baking atmosphere may help prevent the Maillard reactions in bakery products. [ABSTRACT FROM AUTHOR]