Investigation and kinetic evaluation of the reactions of hydroxymethylfurfural with amino and thiol groups of amino acids

Research progress on generation, detection and inhibition of multiple hazards - acrylamide, 5-hydroxymethylfurfural, advanced glycation end products, methylimidazole - in baked goods

While baking produces attractive flavors for foods, it also generates various endogenous by-products, including acrylamide (AA), 5-hydroxymethylfurfural (5-HMF), advanced glycation end products (AGEs) and methylimidazole (MI). This review briefly presents the recent studies on the above hazards, and research progress on the formation and control of the above substances in detail. There have been more detailed studies on a single category of hazards. However, few studies and reports have considered the integrated prevention and control of multiple hazards, which is related to the difficulty of analyzing the reaction mechanisms of multiple hazards at multiple scales and under multiple phases in complex food matrices. In this regard, the sample pretreatment methods are a crucial step in achieving simultaneous detection. The coordinated implementation of various methods, including reducing precursor levels, modifying baking conditions and equipment, and incorporating exogenous additives, is necessary to achieve a synchronized reduction in multiple hazardous substances.

Insight into the Interaction of Malondialdehyde with Rabbit Meat Myofibrillar Protein: Fluorescence Quenching and Protein Oxidation

This research explored the effects of oxidative modification caused by different malondialdehyde (MDA) concentrations on rabbit meat myofibrillar protein (MP) structural characteristics and the interactions between MDA and MP. The fluorescence intensity of MDA-MP adducts, and surface hydrophobicity increased, whereas the intrinsic fluorescence intensity and free-amine content of MPs decreased as MDA concentration and incubation time increased. The carbonyl content was 2.06 nmol/mg for native MPs, while the carbonyl contents increased to 5.17, 5.57, 7.01, 11.37, 13.78, and 23.24 nmol/mg for MP treated with 0.25 to 8 mM MDA, respectively. When the MP was treated with 0.25 mM MDA, the sulfhydryl content and the α-helix content decreased to 43.78 nmol/mg and 38.46%, while when MDA concentration increased to 8 mM, the contents for sulfhydryl and α-helix decreased to 25.70 nmol/mg and 15.32%. Furthermore, the denaturation temperature and ΔH decreased with the increase in MDA concentration, and the peaks disappeared when the MDA concentration reached 8 mM. Those results indicate MDA modification resulted in structural destruction, thermal stability reduction, and protein aggregation. Besides, the first-order kinetics and Stern-Volmer equation fitting results imply that the quenching mechanism of MP by MDA may be mainly driven by dynamic quenching.

Maillard reaction products and amino acid cross-links in liquid infant formula: Effects of UHT treatment and storage

The formation of Maillard reaction products, including Amadori compounds (determined as furosine), advanced glycation end products (AGEs), α-dicarbonyl and furfural compounds, as well as amino acid cross-links (lysinoalanine and lanthionine) was investigated in direct (DI) and indirect (IN) UHT-treated experimental liquid infant formula (IF) during storage at 40 °C. IN-IF had higher concentrations of all investigated compounds compared to DI-IF and low pasteurized IF. IN UHT treatment induced significantly higher concentrations of α-dicarbonyl compounds (glyoxal, methylglyoxal, 3-deoxyglucosone and 3-deoxygalactosone) compared to DI, which facilitated increased formation of AGEs (N-Ɛ-(carboxymethyl)lysine, methylglyoxal- and glyoxal-derived hydroimidazolones) in unstored IFs. During storage for 6 months, concentrations of furosine and AGEs increased while α-dicarbonyl compounds decreased. Principal component analysis indicated that differences between IN-IF and DI-IF disappeared after 2 months of storage. IN-IF had higher concentrations of lysinoalanine and lanthionine and lower concentrations of available lysine and arginine than DI-IF indicating higher loss of protein quality in IN-IF.

Formation of a bioactive cyclopentenone and its adducts with amino acids in sterilized-fruits and - vegetables baby foods

The formation of the molecule 4,5-dihydroxy-2-cyclopenten-1-one (DHCP) from the thermal treatment of pectin-containing foods was investigated in small-scale laboratory preparation of sterilized vegetable puree (carrot, zucchini and tomato) and fruit puree (peach and mixture of pear and apple) and in commercial baby foods. DHCP attracts attention due to its cytotoxicity as well as potential antiviral and anti-inflammatory effects. However, its effects and the difficulty of its identification in food are mediated in part by the formation of Michael adducts of DHCP with amino acids. The results revealed that DHCP reacted efficiently with cysteine and glutathione, and to a lesser extent with histidine. Mass spectrometry analysis confirmed the formation of adducts of DHCP with amino acids in a model system, being in a real food system difficult to investigate. However, these formed adducts are of potential interest, although it is not known whether they are safe, bioactive or reversible.

The antioxidant and antiglycation activities of selected spices and other edible plant materials and their decay in sugar-protein systems under thermal stress

Antiglycation activities of herbs and spices, have been described in relation to their in vivo anti-diabetic or anti-aging activity at physiological temperature. Under the hypothesis that those natural antioxidants may inhibit the formation of Maillard intermediates, the behavior of several hydroalcoholic plant extracts was analyzed in sugar-protein systems. Allspice, thyme, green pepper and black pepper extracts were the most efficient inhibitors, decreasing furosine formation by 60, 45, 40 and 30%, respectively. 5-hydroxymethyl-2-furfural formation decreased in the presence of the extracts and protein glycation was inhibited by the thyme extract in advanced stages. Antiglycation activities were related to polyphenols content, to radical scavenging and to iron-reducing power. In the protein-sugar systems studied at the time in which 4000 ppm of furosine were formed, the antioxidant activity dropped between 30 and 40%. Polyphenols inhibit Maillard intermediates formation, revealing the incidence of oxidative pathways, but they are depleted as a function of time.

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.

Dietary exposure to acrylamide: A critical appraisal on the conversion of disregarded intermediates into acrylamide and possible reactions during digestion

The amount of acrylamide in asparagine rich thermally processed foods has been broadly monitored over the past two decades. Acrylamide exposure can be estimated by using the concentration of acrylamide found in foods and alternatively, biomarkers of exposure are correlated. A better estimation of dietary acrylamide exposure is crucial for a proper food safety assessment, regulations, and public health research. This review addresses the importance of the presence of neglected Maillard reaction intermediates found in foods, that may convert into acrylamide during digestion and the fate of acrylamide in the gastrointestinal tract as a reactive compound. Therefore, it is questioned in this review whether acrylamide concentration in ingested foods is directly correlated with the dietary exposure to acrylamide.

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Neglected Maillard reaction intermediates play role in acrylamide formation in gut.

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Exposure may increase when intermediates are converted into acrylamide in the gut.

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Nucleophiles cause elimination of acrylamide in the intestinal phase.

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The fate of acrylamide during digestion could be important for exposure estimation.

Chemical Stability of Proteins in Foods: Oxidation and the Maillard Reaction

Protein is a major nutrient present in foods along with carbohydrates and lipids. Food proteins undergo a wide range of modifications during food production, processing, and storage. In this review, we discuss two major reactions, oxidation and the Maillard reaction, involved in chemical modifications of food proteins. Protein oxidation in foods is initiated by metal-, enzyme-, or light-induced processes. Food protein oxidation results in the loss of thiol groups and the formation of protein carbonyls and specific oxidation products of cysteine, tyrosine, tryptophan, phenylalanine, and methionine residues, such as disulfides, dityrosine, kynurenine, m-tyrosine, and methionine sulfoxide. The Maillard reaction involves the reaction of nucleophilic amino acid residues with reducing sugars, which yields numerous heterogeneous compounds such as α-dicarbonyls, furans, Strecker aldehydes, advanced glycation end-products, and melanoidins. Both protein oxidation and the Maillard reaction result in the loss of essential amino acids but may positively or negatively impact food structure and flavor. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Acrylamide Content in Breast Milk: The Evaluation of the Impact of Breastfeeding Women's Diet and the Estimation of the Exposure of Breastfed Infants to Acrylamide in Breast Milk

Acrylamide in food is formed by the Maillard reaction. Numerous studies have shown that acrylamide is a neurotoxic and carcinogenic compound. The aim of this study was to determine the level of acrylamide in breast milk at different lactation stages and to evaluate the impact of breastfeeding women's diet on the content of this compound in breast milk. The acrylamide level in breast milk samples was determined by LC-MS/MS. Breastfeeding women's diet was evaluated based on the 24 h dietary recall. The median acrylamide level in colostrum (n = 47) was significantly (p < 0.0005) lower than in the mature milk (n = 26)-0.05 µg/L and 0.14 µg/L, respectively. The estimated breastfeeding women's acrylamide intake from the hospital diet was significantly (p < 0.0001) lower than that from the home diet. We found positive-although modest and borderline significant-correlation between acrylamide intake by breastfeeding women from the hospital diet µg/day) and acrylamide level in the colostrum (µg/L). Acrylamide has been detected in human milk samples, and a positive correlation between dietary acrylamide intake by breastfeeding women and its content in breast milk was observed, which suggests that the concentration can be reduced. Breastfeeding women should avoid foods that may be a source of acrylamide in their diet.

Investigations on the formation of α-dicarbonyl compounds and 5-hydroxymethylfurfural in fruit products during storage: New insights into the role of Maillard reaction

The formation of α-dicarbonyl compounds and 5-hydroxymethylfurfural was investigated under different conditions and the amino acid adducts of them were confirmed using high-resolution mass spectrometry in fruit products during storage. Changes in the concentrations of sugars, amino acids, α-dicarbonyl compounds, and 5-hydroxymethylfurfural in fruit juice concentrates and dried fruits were monitored. Among the dicarbonyls, glucosone was the dominant one in 30 °Bx of fruit juice concentrates, whereas 3-deoxyglucosone was the major in 50 and 70 °Bx of those and in all dried fruits during storage. The highest level of 3-deoxyglucosone was found as 7251 ± 896.6 mg/kg in dried date at the end of the storage. During storage, the loss of free amino acids significantly increased (p < 0.05) in the higher initial reactant concentrations in fruit juice concentrates. The confirmation of amino acid adducts of dicarbonyls and 5-hydroxymethylfurfural generally with high mass accuracy proved the contribution of Maillard reaction to non-enzymatic reactions in fruit products.

Gas chromatographic-ion mobility spectrometry combined with a multivariate analysis model exploring the characteristic changes of odor components during the processing of black sesame

Black sesame (Sesamum indicum L.) is a Chinese dietary herb that has been widely used in the medical and healthcare fields in China. According to the theory of Traditional Chinese medicine processing, reasonable processing (steaming and drying many times) can increase the tonic effect and reduce the adverse factors generated during long-term use. At present, the processing degree of black sesame is mainly judged based on subjective experience. However, due to the lack of objective and quantitative control indicators, quality fluctuations easily occur. Therefore, for better application, its processing technology needs scientific monitoring methods. Herein a gas chromatography-ion mobility spectrometry (GC-IMS) technique was applied as a monitoring method to differentiate the processed products of black sesame in different processing stages. The response data of volatile components obtained from the samples were processed by the built-in data processing software in the instrument to identify the different components for further principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). From fingerprint comparison, 70 differential signal peaks were screened, 32 of which were qualitatively identified, mainly monomers and dimers of 20 compounds. On this basis, the PCA model shows that there was a significant difference between the raw product (S1) and the processed products (H1-9); moreover, there was a certain correlation between the differential changes of samples in different processing stages (H1-9) and the processing times. The OPLS-DA model specifically shows the differential components in the processing with potential characteristics peaks of 41, 105, n-nonanal, 2 and ethanol can discriminate whether the BS has undergone the first processed. And the dynamic changes of the three characteristic peaks of 1-hexanol, acetic acid and 107 can determine the specific degree of processing of BS. The research proves that GC-IMS combined with a multivariate analysis model can provide scientific data for identifying the characteristic odor components of black sesame.

Interaction of Acrylamide, Acrolein, and 5-Hydroxymethylfurfural with Amino Acids and DNA

Acrylamide, acrolein, and 5-hydroxymethylfurfural (HMF) are food-borne toxicants produced during the thermal processing of food. The α,β-unsaturated carbonyl group or aldehyde group in their structure can react easily with the amino, imino, and thiol groups in amino acids, proteins, and DNA via Michael addition and nucleophilic reactions in food and in vivo. This work reviews the interaction pathways of three toxins with amino acids and the cytotoxicity and changes after the digestion and absorption of the resulting adducts. Their interaction with DNA is also discussed. Amino acids ubiquitously exist in foods and are added as nutrients or used to control these food-borne toxicants. Hence, the interaction widely occurring in foods would greatly increase the internal exposure of these toxins and their derived compounds after food intake. This review aims to encourage further investigation on toxin-derived compounds, including their types, exposure levels, toxicities, and pharmacokinetics.

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.

Wholegrain Durum Wheat Bread Fortified With Citrus Fibers: Evaluation of Quality Parameters During Long Storage

The aim of this work was to evaluate the effect of the addition of citrus fibers, from blood orange and lemon peels to produce a functional durum wheat bread. Breads fortified in fiber were packaged under a modified atmosphere (MAP) and stored at 25°C up to 120 days. No significant differences were observed with respect to the specific volume and weight, internal structure, pH and titratable acidity among the bread samples obtained using different types and percentages of fibers. Storage time, at 30 up to 90 days, affected significantly the bread firmness and caused significant differences in 5-hydroxymethylfurfural (HMF) levels in all bread samples. In fortified breads with citrus fibers the yeast and mold counts showed values of approximately 1 log10 cfu/g for the first 30 days and 3.5 log10 cfu/g at the end of storage. The results of the sensory evaluation highlight that loaves enriched with blood orange and lemon fibers showed a citrus flavor but had a similar overall evaluation respect to control bread produced without addition of citrus fiber. The results of this study showed that the addition up to 2% of blood orange and lemon fibers in wheat whole durum flour is a possible strategy to produce "high fibre" bread.

Adducts formed during protein digestion decreased the toxicity of five carbonyl compounds against Caco-2 cells

Acrolein (ACR), glyoxal (GO), methylglyoxal (MGO), hydroxymethylfurfural (HMF), and malondialdehyde (MDA) are toxic contaminants for humans. This work aimed to investigate whether intake of proteins can mitigate their toxicity. Simulated gastrointestinal digestion of proteins from pork, chicken, milk powder and soy protein isolate eliminated amount of ACR, GO, MGO, HMF, and MDA. Among six amino acids, cysteine showed highest capacity for elimination of these toxic compounds through the formation of adducts; it reached the highest elimination capacity for GO, MGO, ACR, MDA, and HMF in 40 min at pH 2.0, and 20 min at pH 7.0. The formed adducts between cysteine and GO, MGO, or ACR showed much lower toxicity against Caco-2 cells. Incubation of the cells with 8 mM GO and MGO for 48 h decreased the cell viability to 16.1%, 16.9% respectively; while incubation of the same concentration of their adducts still kept the cell viability at 82.2% and 81.6% respectively. Cysteine showed much higher detoxifying capacity for ACR than GO and MGO, which can lower the toxicity of ACR toward Caco-2 cells by 80 times.

Absorption of 1-Dicysteinethioacetal-5-Hydroxymethylfurfural in Rats and Its Effect on Oxidative Stress and Gut Microbiota

The absorption of a 5-hydroxymethylfurfural (HMF)-cysteine adduct, 1-dicysteinethioacetal-5-hydroxymethylfurfural (DCH), and its effect on antioxidant activity and gut microbiota were investigated. Results indicated that DCH is more easily absorbed in rats than HMF. Serum DCH concentrations were 15-38-fold of HMF concentrations from 30 to 180 min after intragastrical administration at the level of 100 mg/kg of body weight, and 2.7-4.5% of absorbed DCH was converted to HMF. The malondialdehyde content in the plasma, heart, liver, and kidneys significantly increased after drug (100 mg/kg of bw) administration for 1 week, suggesting that HMF and DCH were oxidative-stress-inducing agents, instead of antioxidant agents, in rats. HMF and DCH also modulated gut microbiota. HMF promoted the growth of Lactobacillus, Tyzzerella, Enterobacter, and Streptococcus. DCH increased the ratio of Firmicutes/ Bacteroidetes and promoted the growth of Akkermansia, Shigella, and Escherichia while inhibiting the growth of Lactobacillus.

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.