Formation and elimination reactions of 5-hydroxymethylfurfural during in vitro digestion of biscuits

Acrylamide, hydroxymethylfurfural and furfural in ready-to-eat foods consumed by child population: Presence, risk assessment and future perspectives

Food intake contributes to adequate growth and neurodevelopment of children. Ready-to-eat foods, frequently consumed by this population, are sources of acrylamide (AA), hydroxymethylfurfural (HMF) and furfural (FF). In this sense, a review of the AA, HMF, and FF presence in ready-to-eat foods was evaluated through a systematic search to infer the risk of exposure in the child population. About 75.8%, 24.2%, and 21% of the studies found AA, HMF, and FF in ready-to-eat foods, respectively. AA is predominant in processed and ultra-processed foods, while HMF and FF are commonly found in fruit-based foods. Only 17.7% of the studies assessed the children's risk of exposure, based on the contaminant concentration in ready-to-eat food and not after gastrointestinal digestion, a more realistic measure. Therefore, with the obtained information and found gaps, it is expected that new strategies will be proposed to assess the vulnerability of the child population to these processing contaminants.

Processing parameters in breadmaking and bioaccessibility of acrylamide and 5-hydroxymethylfurfural

This study aimed to evaluate the fate in digestive steps, bioaccessibility and diffusion of acrylamide (AA) and 5-Hydroxymethylfurfural (5-HMF) in bread samples produced under different processing parameters. AA and 5-HMF were determined in every sample ready-to-eat, after every digestion step and in the digested after crossing the dialysis membrane. The contaminants were extracted by QuEChERS method and determined by HPLC-PDA. Doubling fermentation time (from 60 to 120 min) increased the level of AA by 1.2-fold, and it decreased the level of 5-HMF by 1.4-fold. A combination of 60 min fermentation and 20 min baking led to the lowest levels of AA (1.71 mg/kg) and 5-HMF (0.50 mg/kg). There was no increase in AA level in the gastric stage however, the 5-HMF level increased. Both contaminant levels had increased in the intestinal stage. This fact showed that the determination of the contaminants in the ready-to-eat product did not reflect their actual bioaccessibility because the digestive enzymes and pH variation may affect the release and detection of AA and 5-HMF accumulated in the baking stage. The initial levels of 5-HMF were correlated to the baking time, and initial levels of AA were correlated to the fermentation time. From the bioaccessible levels of AA and 5-HMF, approximately 90 % (5 mg/kg) and 100 % (6.5 mg/kg) crossed the dialysis membrane respectively. Initial and bioaccessible levels of AA were above the security recommendations for bread (50 µg/kg), which is a concern considering the daily consumption of this food. This study showed that focusing on a combination of processing parameters could be a promising strategy to decrease the bioaccessibility of both contaminants in bread.

Pasta cooking influence on in vitro bioaccessibility of type B trichothecenes, acrylamide and hydroxymethylfurfural

The study evaluated the effect of cooking time on the levels of type B trichothecenes (TCT_B), acrylamide (AA) and hydroxymethylfurfural (HMF) in semolina pasta and their bioaccessibilities in order to propose strategies to reduce the daily exposure of these natural and processing contaminants. Three brands of commercial pasta were submitted to different cooking times (7, 10 and 13 min). Subsequently, the in vitro bioaccessibility trials, permeation across the intestinal membrane and estimation of daily exposure were carried out. The lowest cooking time (7 min) resulted in high reductions of TCT_B (88%) and AA + HMF (76.7%) contents found on the raw pasta. The concentrations of deoxynivalenol (DON) and AA were higher after the digestion (bioaccessibilities >100%) than after the pasta cooking. About 25.6% of DON and 100% of AA found in the small intestine digestible fraction were able to permeate the intestinal membrane. The risk of exposure was below the recommended safe limits since the estimated daily exposure values were 0.22 µg/kg per body weight/day for DON and 0.26 µg/kg per body weight/day for AA. Therefore, cooking pasta for 7 min at a pasta:water ratio of 1:10 (w/v) mitigates the contaminants and promotes the greater formation of resistant starch.

Microencapsulates of Blue Maize Polyphenolics as a Promising Ingredient in the Food and Pharmaceutical Industry: Characterization, Antioxidant Properties, and In Vitro-Simulated Digestion

An anthocyanin-rich blue maize waste product was used for anthocyanin extraction. To preserve bioactive phenolic compounds, a spray-drying technique was employed using conventional wall material maltodextrin (MD), with novel one, hydroxypropyl-β-cyclodextrin (HPBCD). The obtained spray-dried maize extract (SME) and microencapsulates were analyzed based on physicochemical powder properties, chemical analysis, antioxidant activity, and digestibility. The examined microencapsulates demonstrated good powder properties, exhibited a high powder yield (up to 83%), and had a low moisture content (less than 5%). HPBCD and MD + HPBCD combinations demonstrated superior powder properties in the terms of decreasing the time necessary for rehydration (133.25 and 153.8 s, respectively). The mean average particle diameter ranged from 4.72 to 21.33 µm. DSC analyses signified high powder thermal stability, around 200 °C, related to the increasing preservation with biopolymer addition. The total phenolic and anthocyanin compounds ranged from 30,622 to 32,211 mg CE/kg (CE-catechin equivalents) and from 9642 to 12,182 mg CGE/kg (CGE-cyanidin 3-glucoside equivalents), respectively, associated with good bioactive compound protection. Microencapsulates with both carriers (15% MD and 15% HPBCD) had the highest digestibility (73.63%). Our results indicated that the microencapsulates created with the active ingredient and the wall materials (MD and HPBCD) could protect phenolic compounds/anthocyanins against ABTS radicals (63.53 and 62.47 mmol Trolox Eq/kg, respectively).

Study on Maillard reaction mechanism by quantum chemistry calculation

CONTEXT

The Maillard reaction is a high-temperature reaction of amino acids and carbohydrates to produce macromolecular substances such as melanoidins and intermediate reducing ketones, aldehydes, and volatile compounds. At present, only very limited researches involved the reaction mechanisms of Maillard reaction, which causes a lot of confusion in understanding numerous food processes. The detailed calculations of Maillard reaction are urgently needed.

METHODS

The density functional theory (DFT) method (M06-2X/6-311G*) was used to deeply explore the specific mechanism of the primary and intermediate stages of Maillard reaction for a selected model system.

RESULTS

The results show that the basic reaction processes in primary stage are the formation of Schiff-base by the condensation of amino and carbonyl groups, and then, Schiff-base tautomerization twice through proton transfer to generate Amadori rearrangement products. In the intermediate stage, two main reaction paths, 1-2 and 2-3 enolization, were comprehensively investigated. The first route finally generates 5-hydroxymethylfurfural through isomerization, dehydration, hydrolysis, elimination, and condensation, and the second route products dicarbonyl compounds through isomerization and elimination and then Strecker degradation forms aldehydes through condensation, decarboxylation, hydrolysis, and elimination. The results show that both paths are involved in complex reactions, some are lower barrier reactions, and some higher barrier reactions. An important aspect is that water catalysis is critical in all of these reactions; it is present in most processes. Our study deepens the understanding of the Maillard reaction from molecular level and facilitate the regulation of some harmful products.

5-Hydroxymethylfurfural Exerts Negative Effects on Gastric Mucosal Epithelial Cells by Inducing Oxidative Stress, Apoptosis, and Tight Junction Disruption

5-Hydroxymethylfurfural (5-HMF) is a processing byproduct present in foods that are consumed daily by humans, and the diet is the principal route for human exposure to it. However, its adverse effects on gastric epithelial cells are not fully understood. Based on the half inhibitory concentration value, concentrations of HMF of 2, 4, 8, and 16 mM were selected for this study. After 5-HMF treatment for 24 h, the number of living cells decreased to 89.61 ± 0.48, 77.30 ± 0.57, 58.75 ± 0.36, and 19.61 ± 0.40% of the control, respectively. Apoptosis activated through both the death receptor and mitochondrial pathways was confirmed to be the primary mode of HMF-induced cell death. Further analysis revealed that the reactive oxygen species (ROS) levels in GES-1 cells increased 1.7-6.5 fold after exposure to 5-HMF. Moreover, the inhibition of ROS by N-acetylcysteine blocked HMF-induced apoptosis and cell proliferation suppression, indicating that oxidative stress was important in HMF-induced apoptosis. Besides, after 5-HMF treatment, the gene expressions of occludin and ZO-1 were reduced by 1.1-3.4 fold and 2.0-9.4 fold, respectively. The cell surface morphology and tight junction-related protein expression analysis also revealed the destructive effect of 5-HMF on tight junction integrity. Our research highlights a potential mechanism of HMF-induced toxicity in GES-1 cells and provides additional information on the health risks of 5-HMF exposure to the human gastric epithelium.

Inhibition Mechanism of L-Cysteine on Maillard Reaction by Trapping 5-Hydroxymethylfurfural

The Maillard reaction (MR) can affect the color, flavor, organoleptic properties, and nutritional value of food. Sometimes, MR is undesirable due to lowering the nutrient utilization, producing harmful neo-formed compounds, etc. In this case, it is necessary to control MR. Some chemical substances, such as phenolic acid, vitamins, aminoguanidine, and thiols extracted from garlic or onion, can effectively prevent MR. In this study, L-cysteine (L-cys) was found to inhibit MR after screening 10 sulfhydryl compounds by comparing their ability to mitigate browning. The inhibition mechanism was speculated to be related to the removal of 5-hydroxymethylfurfural (HMF), a key mid-product of MR. The reaction product of HMF and L-cys was identified and named as 1-dicysteinethioacetal-5-hydroxymethylfurfural (DCH) according to the mass spectrum and nuclear magnetic resonance spectrum of the main product. Furthermore, DCH was detected in the glutamic-fructose mixture after L-cys was added. In addition, the production of DCH also increased with the addition of L-cys. It also was worth noting that DCH showed no cell toxicity to RAW 264.7 cells. Moreover, the in vitro assays indicated that DCH had anti-inflammatory and antioxidant activities. In conclusion, L-cys inhibits MR by converting HMF into another adduct DCH with higher safety and health benefits. L-cys has the potential to be applied as an inhibitor to prevent MR during food processing and storage.

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.

The Influence of In Vitro Gastrointestinal Digestion on the Chemical Composition and Antioxidant and Enzyme Inhibitory Capacities of Carob Liqueurs Obtained with Different Elaboration Techniques

Carob liqueur is a traditional Mediterranean alcoholic beverage obtained via a wide range of production techniques contributing to the different organoleptic attributes of the final product. The aim of this research was to evaluate the stability of the chemical composition and biological capacities (antioxidant and enzyme inhibition) under in vitro simulated gastrointestinal digestion of liqueurs prepared by flavouring the fig spirit with carob pulp by maceration, distillation, percolation, or aqueous and hydro-alcoholic infusions. For this purpose, the phenolic and furanic compositions, the total phenolic (TPC) and flavonoid (TFC) contents, antioxidant capacity (AC), and enzyme inhibitory potential against acethylcholinesterase, tyrosinase, α-glucosidase and α-amylase enzymes were evaluated. The content of gallic acid decreased after gastrointestinal digestion, while TPC, TFC, and AC significantly increased after each digestion phase. Overall, no significantly different enzyme inhibitions (p < 0.05) were observed among digested liqueurs, with moderate inhibition against acethylcholinesterase and tyrosinase (enzymes related with neurodegenerative diseases), and potent and low inhibitory capacities for α-glucosidase and α-amylase, respectively (ideal conditions employed in antidiabetic therapy). The study indicates that hydro-alcoholic infusion and maceration were the most appropriate methods to obtain liqueurs with higher values of the aforementioned parameters and safe levels of toxic furanics.

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.

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.