Formation and reduction of 5-hydroxymethylfurfural at frying temperature in model system as a function of amino acid and sugar composition

The relationship between the deterioration of frying oil and the generation of hazards during frying

Deep-fat frying gives food a desirable color and flavor but inevitably leads to oil deterioration and production of hazards. In this study, the simultaneous generation of multiple hazards under different frying conditions was investigated, the deterioration of frying oil was evaluated, and finally, their correlation was analyzed. The results showed that as the temperature of frying chicken wings increased from 150 to 190 °C, the levels of acrylamide (AA), heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs) in the oil also increased proportionally. At 190 °C, the fried potato oil contained the highest AA content of 2.60 mg·kg-1, while the content of HCAs and PAHs was the highest in fried chicken wings oil, with values of 5.06 μg·kg-1 and 5.18 μg·kg-1, respectively. 5-Hydroxymethylfurfural was detected only in fried potato oil. Oil quality deteriorated gradually with increasing frying temperature and heating time, as indicated by increased acid value, carbonyl value, and levels of total polar compounds. Overall, the results indicated hazards were positively correlated with oil deterioration, suggesting that oil deterioration contributed to the generation of hazards. This work links hazards and oil deterioration, which is crucial for improving the quality and safety of fried foods, while reducing negative environmental impacts, and achieving clean production.

The variation of acrylamide and 5-hydroxymethylfurfural in tea with different roasting degrees and the effects of tea polyphenols on their formation

BACKGROUND

Roasting is an essential step in making roasted teas, and its role in producing flavors has been widely studied. However, the variation of potential hazardous compounds during the tea roasting process is still vague. The present study established an effective method based on liquid chromatography-triple quadrupole-tandem mass spectrometry to simultaneously determine the variation of acrylamide (AA), 5-hydroxymethylfurfural (5-HMF), and free amino acids during the tea roasting process. Meanwhile, the effects of several tea polyphenols on the formation of AA and 5-HMF were investigated by a wet-to-dry thermal model reaction.

RESULTS

Medium-temperature roasted teas had the highest levels of AA and 5-HMF, with ranges of 0.13-0.15 μg g-1 and 68.72-123.98 μg g-1, respectively. Quantitative results showed that the levels of monosaccharides and amino acids decreased during roasting, which might contribute to the formation of 5-HMF and AA. Meanwhile, the decrease of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin (EC) might be related to their inhibitory effects on 5-HMF and AA. Thermal model reaction results showed that EGCG and EC significantly inhibited 5-HMF formation with a decline rate of 33.33% and 72.22%, respectively, mainly by trapping glucose. Gallic acid (GA) also had an inhibitory effect on the formation of AA (decreased by 92.86%) and 5-HMF (44.44%), mainly through impeding the preliminary reaction of asparagine and glucose.

CONCLUSION

The roasting temperature determined the levels of AA and 5-HMF in teas. Catechins inhibited the formation of 5-HMF and AA mostly through trapping monosaccharides, while the inhibitory effect of GA was achieved by impeding the reaction. © 2024 Society of Chemical Industry.

Analysis of volatile compounds and 5-hydroxymethylfurfural in fried chicken breast produced by air and deep-fat frying

Two samples, simple-battered chicken (SBC) and normal-battered chicken (NBC), with different batters were deep-fat fried at various conditions and volatile compounds and 5-hydroxymethylfurfural (5-HMF) was analysed. The moisture content of the air-fried samples was significantly higher than that of the deep-fat fried samples in the same batter samples. A total of 72 volatile compounds (8 aldehydes, 15 monoterpenes, 12 sesquiterpenes, 2 terpene alcohols, 4 benzenes, 13 pyrazines, 2 pyridines, 6 furans, 5 alcohols, 2 pyrroles, and 3 others) were detected in fried chicken breast, and air-fried SBC possessed the highest total amount of volatile compounds. Furthermore, 5-HMF was exclusively detected in NBC samples; in particular, 1.27 ± 0.06 and 0.41 ± 0.02 μg/mL were detected in deep- and air-fried NBC, respectively. This study indicates the potential of air frying to reduce the formation of 5-HMF while maintaining quality characteristics, suggesting the need for further study on other hazardous compounds.

Study on the non-enzymatic browning of lotus rhizome juice during sterilization mediated by 1,2-dicarboxyl and heterocyclic compounds

BACKGROUND

Lotus rhizome juice (LRJ) is susceptible to the Maillard reaction (MR) and caramelization, which tend to cause a reduction in quality and lower consumer acceptance of the product. 1,2-Dicarbonyl compounds (DCs) and heterocyclic compounds have attracted increasing attention as key intermediates responsible for the formation of brown pigments during MR and caramelization. However, little is known about the effects of these two types of compounds on brown pigments in LRJ during sterilization. This study quantified the changes in brown intensity (A420), DCs, and heterocyclic compounds before and after spiking, and identified the precursors and intermediates for brown pigment formation as well as the formation pathways of the intermediates.

RESULTS

The spiking experiments suggested that spiking with fructose resulted in more 3-deoxyglucosone (3-DG) and 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP), while that with lysine led to more glucosone (GS) and 2,3-butanedione (2,3-BD) in LRJ. The addition of glucose, asparagine, and glutamine promoted the formation of 5-hydroxymethylfurfural (HMF) significantly, whereas the addition of glucose, lysine, and asparagine resulted in more norfuraneol. Spiking with reducing sugars and amino acids promoted both glyoxal (GO) and methylglyoxal (MGO), and the effect of glucose on GO was particularly significant. Correlation analysis showed that A420 had the highest correlation with 3-DG in the fructose- and lysine-spiked group, and with HMF in the glucose-, asparagine-, and glutamine-spiked groups.

CONCLUSION

This study revealed that fructose, glucose, asparagine, glutamine, and lysine were essential precursors of MR and caramelization in LRJ during sterilization. 3-Deoxyglucosone and DDMP were mainly produced by caramelization with fructose as the primary precursor, whereas GS and 2,3-BD were primarily formed via MR with lysine catalysis. The MR and caramelization were the main formation pathways of HMF (catalyzed by asparagine and glutamine) and norfuraneol (catalyzed by lysine and asparagine), with glucose as the critical precursor. Methylglyoxal was mainly produced by MR or caramelization, and caramelization was the main formation pathway of GO, with glucose as the precursor. Dor brown pigment formation from fructose and lysine, 3-DG was identified as the most crucial intermediate, while for that from glucose, asparagine, and glutamine, HMF was found to be the most important intermediate. © 2023 Society of Chemical Industry.

Investigation on the simultaneous inhibition of advanced glycation end products, 4-methylimidazole and hydroxymethylfurfural in thermal reaction meat flavorings by liquiritigenin, liquiritin and glycyrrhizic acid and possible pathways

The inhibitory effects of liquiritigenin, liquiritin and glycyrrhizic acid against the hazards during the preparation of thermal reaction beef flavoring were investigated using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Liquiritigenin(1.5 mM) inhibited Nε-carboxymethyl-L-lysine and Nε-carboxyethyl-L-lysine by up to 38.69 % and 61.27 %, respectively; 1.5 mM liquiritin inhibited 4-methylimidazole by up to 48.28 %; and 1.5 mM liquiritigenin and 1.0 mM liquiritin inhibited hydroxymethylfurfural by up to 61.20 % and 59.31 %, respectively. The results of the model system showed that the inhibitory effect of the 3 inhibitors could be extended to other thermal reaction flavoring systems. The 3 inhibitors can effectively block key intermediates in beef flavoring, and liquiritigenin can inhibit up to 22.97 % of glyoxal and 22.89 % of methylglyoxal. In addition, liquiritigenin and liquiritin can directly eliminate up to 25.87 % and 21.01 % of methylglyoxal by addition and other means. Free radicals in the simultaneous formation model system were measured using electron spin resonance (ESR), and the results showed that liquiritigenin, liquiritin and glycyrrhizic acid could scavenge free radicals in the system in a dose-dependent manner, with scavenging rates of up to 44.88-57.09 %. Therefore, the inhibitory effects of the 3 inhibitors can be attributed to the intermediate blocking and free radical scavenging pathways.

Effects of Konjac Glucomannan on Oil Absorption and Safety Hazard Factor Formation of Fried Battered Fish Nuggets

The purpose of this study was to investigate the effects of konjac glucomannan (KGM) on oil absorption and the formation of safety hazard factors in fried battered fish nuggets by measuring advanced glycation end products (AGEs) and acrylamide contents. Other physicochemical properties were determined to explore the reason for oil absorption and formation of safety hazard factors. The acrylamide was found mainly in the crust. The addition of 0.8% KGM could significantly reduce the acrylamide content (p < 0.05). For the battered sample, the AGEs content was far lower than the unbattered. The addition of 0.8% KGM could significantly reduce the AGEs content in the inner layer (p < 0.05). The microstructure showed that the sample with 0.8% KGM had the most compact crust. The compact crust reduced oil and malondialdehyde contents. Combined with the other indicators, the inhibitory effect of 0.8% KGM on acrylamide was closely related with the decreased extent of oil oxidation and Maillard reaction in the samples with 0.8% KGM. The inhibitory effect of 0.8% KGM on AGEs might originate from its lower oil content.

Effect of Chitosan Incorporation on the Development of Acrylamide during Maillard Reaction in Fructose-Asparagine Model Solution and the Functional Characteristics of the Resultants

The objectives of this study were to evaluate the effect of 0.5% chitosan incorporation on acrylamide development in a food model solution containing 0.5% fructose and asparagine after heating for 30 min at 180 °C. All the solutions were investigated for the following characteristics: acrylamide, asparagine, reducing sugar content, color, kinematic viscosity, Maillard reaction products (MRPs), and pH every 10 min. After heating for 10 min, the viscosity of chitosan-containing solutions reduced significantly. The investigational data confirmed that chitosan may have decomposed into lower molecular structures, as demonstrated by the reduced viscosity of the solution at pH < 6 and a decrease in the acrylamide content during 30 min of heating in a fructose−asparagine system. This study also confirms that the formation of ultraviolet-absorbing intermediates and browning intensity of MRPs containing acrylamide prepared by fructose−asparagine was more than those of MRPs prepared by glucose−asparagine solution system. MRPs containing acrylamide resulted from the reaction of asparagine with fructose (ketose) rather than glucose (aldose). Acrylamide formation could be significantly mitigated in the fructose−asparagine−chitosan model system as compared to the fructose−asparagine model system for possible beverage and food application.

Study of the formation of food hazard factors in fried fish nuggets

Fried fish nuggets were prepared from grass carp. The effects of frying time (180℃, 4-6 min) and pretreatment on the formation of food hazard factors in fried fish nuggets were investigated. Advanced glycation endproducts (AGEs), acrylamide (AA), 5-hydroxymethyl furfural (5-HMF), benzo (a) pyrene (BaP) and trans fatty acids (TFAs) mainly presented on the surface of fried samples, but only few AGEs were detected in the interior. The extension of frying time promoted lipid oxidation and the formation of food hazard factors. At the same frying time, the contents of AA, 5-HMF, TFAs and fluorescent AGEs in flour-coated fish nuggets were higher than those in direct fried fish nuggets, while the contents of N^ε-carboxymethyllysine (CML) and BaP were lower. Overall, CML and BaP were the main food hazard factors of the direct fried samples, AA was the main food hazard factor of the flour-coated fried samples.

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).

The simultaneous inhibition of histidine on 5-hydroxymethylfurfural and acrylamide in model systems and cookies

5-Hydroxymethylfurfural (HMF) and acrylamide (AA) are neoformed food contaminants. In this study, the simultaneous inhibition of HMF and AA by histidine (His) were investigated. In the asparagine (Asn)/glucose (Glc) model system, the inhibition ratios of HMF and AA were in the range of 28-58% and 0-71% when 20 mmol/L His was added. In cookies, His also exhibited excellent inhibition effects on both HMF and AA. At the His concentration of 2% (w/w), the inhibition ratios of HMF and AA reached 90% and 65%. Additionally, the sensory quality of cookies was not affected significantly. Qualitative results suggested that His inhibited the formation of AA by the competitive reaction between His and Asn for Glc, as well as directly eliminated the formed HMF and AA via the carbonyl-amine reaction and the Michael addition, respectively. This study revealed that His could be applied for the inhibition of HMF and AA in heated food.

Effect of Different Sterilization Methods on the Microbial and Physicochemical Changes in Prunus mume Juice during Storage

This study evaluated the pasteurization (P), ozone (O3), ultrasonic (US), and high-hydrostatic-pressure (HHP) sterilization approaches for processing of Prunus mume regarding browning factors and microorganisms, compared with non-sterilization (control check, CK) treatment. The microorganisms (total bacterial count and fungi and yeast count) in the juice were identified after different sterilization techniques, while the quality parameter changes (degree of browning, color measurements, total phenolic content, reducing sugar, ascorbic acid, 5-hydroxymethyl furaldehyde (5-HMF), amino acid nitrogen, total soluble solids (TSS), pH value) were investigated. The results indicate that P and HHP treatment reduced non-enzymatic browning while substantially impacting the color measurements, TSS, and pH, while the sterilization effect was remarkable, with a rate exceeding 90%. Furthermore, the Prunus mume juices treated with P and HHP sterilization were used as the objects, and the CK group was used as the control group. They were placed at 4 °C, 25 °C and 37 °C, respectively, and stored in dark for 15 d. Sampling and determination were carried out on 0, 3, 6, 9, 12, and 15 d, respectively. M-&-Y (molds and yeasts) were not detected in the late storage period, and no obvious microbial growth was observed during storage, indicating that P and HHP treatments could ensure the microbial safety of Prunus mume juice. P- and HHP- treated Prunus mume juice has better quality and low temperature storage is beneficial for maintaining the quality of Prunus mume juice. Therefore, P treatment or HHP treatment combined with low temperature storage could achieve a more ideal storage effect. Overall, this study conclusively established that P and HHP methods were suitable for sterilizing Prunus mume juice. These techniques minimally affected overall product quality while better maintaining the quality parameters than the untreated juice samples and those exposed to O3 and US treatment.

Effect of Hydroxymethylfurfural and Low-Molecular-Weight Chitosan on Formation of Acrylamide and Hydroxymethylfurfural during Maillard Reaction in Glucose and Asparagine Model Systems

The aim of this research was to investigate the effects of the addition of 0.5% hydroxymethylfurfural (HMF) and low molecular chitosan on acrylamide and HMF formation in a food model system, which contains 0.5% glucose, asparagine, and HMF within 30 min of heating at 180 °C. At an interval of 10 min, all solutions were evaluated in the following aspects: reducing sugar, asparagine, acrylamide, HMF content, pH, Maillard reaction products, kinematic viscosity, and color. After heating for 10 min, the kinematic viscosity of solutions containing chitosan reduced significantly. The values of the acrylamide, HMF, and absorbance increased at OD₂₉₄ and OD₄₂₀ (optical density measured at 294 nm and 420 nm) of solutions. Experimental results showed that low-molecular-weight chitosan might be hydrolyzed into much lower molecular weight, followed by the decrease in kinematic viscosity of the solution at pH lower than 6 and the increase in the formation of acrylamide after heating for 30 min.

Kinetics of α‑dicarbonyl compounds formation in glucose-glutamic acid model of Maillard reaction

As a potential health hazard, α-dicarbonyl compounds have been detected in the thermally processed foods. In order to investigate the formation kinetics of α-dicarbonyl compounds, liquid chromatography-electrospray tandem mass spectrometry was employed to determine the content of α-dicarbonyl compounds in glucose-only and glucose-glutamic acid (glucose-Glu) thermal reaction models. The 3-deoxyglucosone content was significantly higher than 6 α-dicarbonyl compounds at 90-110℃, 0-6 hr in the two tested systems. The glutamic acid promoted the content accumulation of 1-deoxyglucosone, diacetyl, methylglyoxal, and glyoxal, whereas inhibited the content of 3-deoxyglucosone and 3,4-dideoxyglucosone. Three-fifths of the tested compounds content increased linearly with time increasing, but in glucose-only system, the 1-deoxyglucosone content increased logarithmically at 95-110℃ over reaction time. The formation of glucose (100-110℃, glucose-only and glucose-Glu), 5-hydroxymethylfurfural (100-110℃, glucose-only), 1-deoxyglucose (105-110℃, glucose-Glu), 3,4-dideoxyglucosone (110℃, glucose-Glu), glyoxal (95-110℃, glucose-Glu) and diacetyl (90-95℃, glucose-Glu) could be well fitted by exponential equation. Shortening the heating time and reducing heating temperature (except glyoxal in glucose-only system) were the effective methods to decrease α-dicarbonyl compounds content in the two tested systems. Additionally, high temperature could also reduce α-dicarbonyl compounds content, such as 3-deoxyglucosone (≥110℃, glucose-only), 1-deoxyglucosone (≥110℃, glucose-only), glucosone (≥110℃, glucose-only; ≥100℃, glucose-Glu), methyloxyl (≥110℃, glucose-only; ≥100℃, glucose-Glu), diacetyl (≥110℃, glucose-only), and glyoxal (≥100℃, glucose-Glu).

Green biorefinery - the ultra-high hydrolysis rate and behavior of Populus tomentosa hemicellulose autohydrolysis under moderate subcritical water conditions

A high monosaccharide conversion rate of hemicellulose in a green solvent and under moderate reaction conditions for industrialization is one of the most important keys in a lignocellulosic biorefinery. The behavior of Populus tomentosa hemicellulose polysaccharides, crystallinity and the furfural formation in the autohydrolysis process under moderate subcritical water conditions (160-180 °C, 0.618-1.002 MPa) were studied. The results have shown that the hemicellulose was converted to corresponding monosaccharides at an ultra-high hydrolysis rate. Factor analysis indicates that the temperature is the most important factor affecting hemicellulose autohydrolysis. When the autohydrolysis temperature increased from 160 to 180 °C for 2 h, the hydrolysis rate of xylose, rhamnose, galactose, mannose, and glucose from hemicellulose increased from 70% to 91%, 71% to 100%, 82% to 95%, 42% to 58%, and 34% to 37%, respectively. Arabinose was completely dissolved in 30 min. The xylose, rhamnose, galactose, and arabinose from hemicellulose could be almost completely removed under the conditions. The hemicellulose removal rate obtained herein exceeded the values reported for most acid, alkali, ionic liquid, or deep eutectic solvent treatments. It is notable that almost all glucose in hemicellulose was dissolved and the glucose in cellulose was partially hydrolyzed. An analysis of the sugar composition and the crystallinity change in the process at 180 °C demonstrate that hydrolysis reaction started to shift from amorphous regions to crystalline regions, due to the partial hydrolysis of crystalline cellulose after 90 min at 180 °C. Overall, these results show that the moderate subcritical water autohydrolysis of hemicellulose in Populus tomentosa may be a potential bio-refinery process.

Formation and Identification of Two Hydroxmethylfurfural-Glycine Adducts and Their Cytotoxicity and Absorption in Caco-2 Cells

Our previous research showed that thioacetal and Schiff base formed between 5-hydroxymethylfurfural (HMF) and cysteine or lysine considerably decreased the cytotoxicity of HMF. In this study, two adol condensation adducts, named 2β-amino-3α-hydroxy-3-(5-(hydroxymethyl)furan-2-yl)propanoic acid (HGA) and 2α-amino-3β-hydroxy-3-(5-(hydroxymethyl)furan-2-yl)propanoic acid (HGB), were prepared from the reaction products of glycine and HMF, and their cytotoxicities were investigated in Caco-2 cells. Compared with HMF, HGA and HGB displayed lower cytotoxicities against Caco-2 cells with IC₅₀ values of 36.50 and 43.47 mM, respectively, versus 16.11 mM (HMF). In contrast to our findings in thioacetal and Schiff base products, HGA and HGB underwent a very high metabolism rate (99%) in Caco-2 cells. HGA and HGB may degrade to other products instead of HMF since no extracellular or intracellular HMF was detected.

Identification of a 5-Hydroxymethylfurfural-Lysine Schiff Base and Its Cytotoxicity in Three Cell Lines

5-Hydroxymethylfurfural (HMF) can undergo the Maillard reaction with amino acids. However, the safety of the products remains unknown. In this study, a HMF-lysine Schiff base named (E)-N⁶-((5'-(hydroxymethyl)furan-2'-yl)methylene)lysine (HML) was identified and detected for the first time in baked foods. HML formation significantly decreased the cytotoxicity (IC₅₀) of HMF against GES-1 cells (81.81 versus 5.02 mM and 73.76 versus 2.94 mM for HML versus HMF at 24 and 48 h, respectively), EA.hy926 cells (86.05 versus 4.85 mM and 77.22 versus 0.71 mM, respectively), and Caco-2 cells (155.77 versus 36.84 mM and 112.70 versus 18.51 mM, respectively). Exposure of Caco-2 cells to HMF at 10.0 mM triggered cell apoptosis of 14.02% (versus 8.54% in the control), whereas exposure to HML at 10-15 mM hardly increased cell apoptosis. Moreover, the absorption capacities of HMF and HML by Caco-2 cells were equivalent (p > 0.05) at 7.23-12.57% after incubation at 2 mM for 30-150 min.

Modelling Contaminant Formation during Thermal Processing of Sea Buckthorn Purée

Background: The impact of thermal treatment on acrylamide (ACR) and hydroxymethylfurfural (HMF) formation was investigated for thermally treated sea buckthorn purée. Methods: An optimized procedure for minimizing ACR and HMF formation in thermally treated sea buckthorn purée was described. The precursors of ACR and HMF and their impact in heating of sea buckthorn purée to obtain jam-like products were also evaluated. Results: The contaminant content formed in samples was analyzed on thirteen running variants using a temperature range of 59.3-200.7 °C, and for heating durations between 5.9 and 34.1 min. The calculated equations of contaminant formation in sea buckthorn purée have established that the minimum content is formed at the lowest exposure time, between 10 and 20 min, for both ACR and HMF. The lowest ACR content was attained at 5.9-min exposure time and 130 °C temperature (0.3 µg/kg). For HMF the results revealed a lower quantity at 59.3 °C for 20-min exposure time (1.4 mg/kg). Conclusions: the found model is useful for the prediction of the best temperature/time conditions of the thermal treatment to obtain the lowest contaminates levels in the final product.

Kinetics of 5-hydroxymethylfurfural formation in the sugar-amino acid model of Maillard reaction

BACKGROUND

As a potential health hazard, 5-hydroxymethylfurfural (HMF) has been detected in thermally processed foods high in sugar and amino acids. In order to analyze HMF quantitatively and investigate the kinetics of its formation, high-performance liquid chromatography was employed to determine the content of HMF in six sugar-amino acid thermal reaction models.

RESULTS

In thermal reaction models, formation of HMF was significantly affected by sugar and amino acid composition, pH value and heating conditions. HMF formation increased with increasing sugar and amino acid (cysteine excepted) content, temperature and reaction time. A maximum amount of HMF of 1.50 g kg^-1 was detected in the sucrose-glutamic acid model at 110 °C and 6 h. Low pH value and added acidic amino acids promoted the formation of HMF, especially in the sucrose-containing system.

CONCLUSION

HMF formation followed first-order kinetics in four models, including the model of glucose-cysteine, glucose-glutamic acid, glucose-leucine and sucrose-leucine. In contrast, HMF formation followed zero-order kinetics in the model of sucrose-glutamic acid. The quantity of HMF increased as the quantity of sugar and amino acid increased (cysteine excepted) in six tested models. © 2018 Society of Chemical Industry.

Physicochemical Properties of Liquid Infant Formula Stored at Different Temperatures

Changes in the physicochemical properties of ready-to-feed liquid infant formula (LIF) stored at different temperatures (10, 20, 30, and 40°C) for 6 mon, focusing on 5-hydroxymethylfurfural (HMF) content, color, pH, fat globule size distribution, and rheological properties were determined. The HMF content increased with storage time, and LIF stored at 40°C had a higher HMF content than that of LIF stored at 10°C. The lightness (L*) decreased while redness (a*) and yellowness (b*) increased with increasing HMF content. The fat globule size and pH of LIF stored at 10°C did not change. However, in the case of LIF stored at 30°C and 40°C, the fat globule size increased and the pH decreased during storage for 6 mon. LIF stored at 40°C had a higher apparent viscosity (η_a,10) than that of LIF stored at 10°C, and the shear-thinning behavior of LIF stored at higher temperature was stronger than that of LIF stored at low temperature. The physicochemical changes of LIF during storage were accelerated by Maillard reaction (MR) at higher storage temperatures. Therefore, even if LIF is aseptically manufactured, we recommend that sterilized LIF should be stored at low temperature in order to minimize quality changes during storage.

Formation of a Hydroxymethylfurfural-Cysteine Adduct and Its Absorption and Cytotoxicity in Caco-2 Cells

Adducts of 5-hydroxymethylfurfural (HMF)-amino acids are formed during food processing and digestion; the elimination capacity of in vitro intestinal digests of biscuits, instant noodles, and potato crisps for HMF is 652, 727, and 540 μg/g, respectively. However, the safety of these adducts is unknown. In this study, an HMF-cysteine adduct named 1-dicysteinethioacetal-5-hydroxymehtylfurfural (DCH), which was found to be produced in the gastrointestinal tract after HMF intake, was prepared to test its effect toward Caco-2 cells. Compared with HMF, the adduct displayed lower cytotoxicity against Caco-2 cells with an IC₅₀ value of 31.26 mM versus 14.95 mM (HMF). The DCH did not induce cell apoptosis, whereas HMF significantly increased the apoptosis rate after incubation at concentrations of 16, 32, and 48 mM for 72 h. DCH showed an absorption rate considerably lower than that of HMF by Caco-2 cells. Lower absorption of DCH may result in lower toxicity compared with HMF against Caco-2 cells. Intracellular transformation of DCH has been observed.

Nitrone formation: A new strategy for the derivatization of aldehydes and its application on the determination of furfurals in foods by high performance liquid chromatography with fluorescence detection

A nitrone formation method using a novel fluorescent reagent 4-hydroxylaminopropyl-7-methoxylcoumarin (HAMC) has been developed and applied for the determination of furfurals in foods using high performance liquid chromatography with fluorescence detection (HPLC-FLD). Furfurals samples were derivatized by HAMC in aqueous condition at room temperature in less than 30min and were subjected to direct HPLC-FLD analysis without extra purification or extraction. Compared with other conventional methods, nitrone formation method produced single chromatographic peak for each analyte, leading to simpler chromatograms and enhancing the overall sensitivity. Low detection limits at sub-nM level (0.08-0.1nM) and high repeatabilities (intra-day RSD ≤ 4.2% and inter-day RSD ≤ 6.7%) were achieved. The linear range of the calibration curve was 0.2-4000nM with good correlation coefficients (R ≥ 0.9989). This method was successfully applied for furfurals determination in food samples, including honey and coffee. The accuracy was satisfactory with recoveries ranging from 89.7% to 106.7% Above all, this pre-column derivatization method is simple, reliable and highly sensitive, providing a promising way for future studies of aldehydes from various sources.

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.