Dietary glycation compounds - implications for human health.

The term "glycation compounds" comprises a wide range of structurally diverse compounds that are formed endogenously and in food via the Maillard reaction, a chemical reaction between reducing sugars and amino acids. Glycation compounds produced endogenously are considered to contribute to a range of diseases. This has led to the hypothesis that glycation compounds present in food may also cause adverse effects and thus pose a nutritional risk to human health. In this work, the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) summarized data on formation, occurrence, exposure and toxicity of glycation compounds (Part A) and systematically assessed potential associations between dietary intake of defined glycation compounds and disease, including allergy, diabetes, cardiovascular and renal disease, gut/gastrotoxicity, brain/cognitive impairment and cancer (Part B). A systematic search in Pubmed (Medline), Scopus and Web of Science using a combination of keywords defining individual glycation compounds and relevant disease patterns linked to the subject area of food, nutrition and diet retrieved 253 original publications relevant to the research question. Of these, only 192 were found to comply with previously defined quality criteria and were thus considered suitable to assess potential health risks of dietary glycation compounds. For each adverse health effect considered in this assessment, however, only limited numbers of human, animal and in vitro studies were identified. While studies in humans were often limited due to small cohort size, short study duration, and confounders, experimental studies in animals that allow for controlled exposure to individual glycation compounds provided some evidence for impaired glucose tolerance, insulin resistance, cardiovascular effects and renal injury in response to oral exposure to dicarbonyl compounds, albeit at dose levels by far exceeding estimated human exposures. The overall database was generally inconsistent or inconclusive. Based on this systematic review, the SKLM concludes that there is at present no convincing evidence for a causal association between dietary intake of glycation compounds and adverse health effects.

Considering the implication of endogenous glycation compounds in aging and disease, dietary exposure via consumption of an "AGE (advanced glycation end product) rich diet" is increasingly suggested to pose a potential health risk. However, studies attempting to assess an association between dietary glycation compounds and adverse health effects frequently suffer from insufficient chemical analysis of glycation compounds, including inadequate structural characterization and limited quantitative data. The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) previously defined quality criteria for studies designed to assess the effects of dietary glycation compounds on human health. The aim of the present work is to summarize data on formation, occurrence, exposure and toxicity of glycation compounds (Part A) and to systematically evaluate if the currently available scientific database allows for a conclusive assessment of potential health effects of defined glycation compounds (Part B).The term "glycation compounds" comprises a wide range of structurally diverse compounds that derive from the Maillard reaction, a chemical reaction between reducing carbohydrates and amino compounds that occurs during food processing. In the first stage of the Maillard reaction, reducing sugars such as glucose and fructose react for instance with the ε-amino group of lysine, which is most abundant in food ("glycation" of lysine). Subsequently, these primary reaction products undergo Amadori rearrangement to yield products (ARP) such as fructosyllysine (FL) from glucose and also Heyns rearrangement products (HRPs) such as glucosyl- and mannosyllysine from fructose. While ARPs are rapidly formed during food processing, they are not stable and undergo degradation reactions, predominantly to 1,2-dicarbonyl compounds such as glyoxal (GO), methylglyoxal (MGO) and 3-deoxyglucosone (3-DG), which are highly reactive. The last stage of the Maillard reaction is characterized predominantly by the reaction of these dicarbonyl compounds with nucleophilic groups of proteins. The side-chains of lysine and arginine residues as well as the N-termini of proteins are important reaction sites. Carboxyalkylated amino acids such as N-ε-carboxymethyllysine (CML) and N-ε-carboxyethyllysine (CEL) result from reaction of the ε-amino group of lysine with the dicarbonyl compounds GO and MGO. Dicarbonyl compounds with C5 or C6 chains can form cyclic pyrrole derivatives at the ε-amino group of lysine. The most important example for this reaction is pyrraline, which is formed from reaction of 3-DG and lysine. The reaction of dicarbonyl compounds with the guanidino group of arginine mainly leads to hydroimidazolones, of which the MGO-derived hydroimidazolone 1 (MG-H1) is best described in food systems.ARPs are the most abundant glycation products found in food. Up to 55% of the lysine residues in food may be modified to ARPs at the side-chain. Food items particularly rich in ARPs include bread, rusk, biscuits, chocolate, and powdered infant formulas. Exposure estimates range between 0.6­1.6 mg/kg body weight (bw), although exposure may be as high as 14.3 mg/kg bw in individuals consuming foods with extreme ARP concentrations. Foods particularly rich in dicarbonyl compounds include heat-treated or long-term stored items rich in reducing sugars such as jams, alternative sweeteners, soft drinks, honey, candies, cookies, and vinegars, especially balsamico-type vinegars. The main contributors to the daily intake of MGO, GO, and 3-DG are coffee and bread. Dietary exposure to dicarbonyl compounds has been estimated to range between 0.02­0.29 mg/kg bw/d for MGO, 0.04­0.16 mg/kg bw/d for GO, 0.14­2.3 mg/kg bw/d for 3-DG, and 0.08­0.13 mg/kg bw/d for 3-deoxygalactosone (3-DGal). Dietary intake of 5-hydroxymethylfurfural (HMF), which can be formed from 3-DG, is estimated to range between 0.0001­0.9 mg/kg bw/d. Exposure estimates for individual glycated amino acids range from 0.03­0.35 mg/kg bw/d for CML, 0.02­0.04 mg/kg bw/d for CEL and 0.19­0.41 mg/kg bw/d for MG-H1. From a model diet consisting of 1 L milk, 500 g bakery products and 400 mL coffee, an intake of pyrraline corresponding to 0.36 mg/kg bw/d for a 70 kg person was estimated.Quantitative analysis of individual glycation compounds or their metabolites in tissues or body fluids as well as their reaction products with amino acids, proteins or DNA may serve to monitor exposure to glycation compounds. However, since glycation compounds are also formed endogenously, these biomarkers reflect the totality of the exposure, making it inherently difficult to define the body burden due to dietary intake against the background of endogenous formation.Information on the toxicokinetics and toxicity of glycation compounds is scarce and mostly limited to the reactive dicarbonyl compounds GO, MGO, 3-DG, HMF, and individual glycated amino acids such as CML and CEL. Acute toxicity of dicarbonyl compounds is low to moderate. There are some data to suggest that rapid detoxification of dicarbonyls in the gastrointestinal tract and liver may limit their oral bioavailability. Biotransformation of GO and MGO occurs predominantly via the glutathione (GSH)-dependent glyoxalase system, and to a lesser extent via glutathione-independent aldo-keto-reductases, which are also responsible for biotransformation of 3-DG. GO, MGO and 3-DG readily react with DNA bases in vitro, giving rise to DNA adducts. There is clear evidence for genotoxicity of GO, MGO and 3-DG. Repeated dose toxicity studies on GO consistently reported reduced body weight gain concomitant with reduced food and water consumption but did not identify compound related changes in clinical chemistry and hematology or histopathological lesions. There is also no evidence for systemic carcinogenicity of GO and MGO based on the available studies. However, initiation/promotion studies indicate that oral exposure to GO may exhibit genotoxic and tumor promoting activity locally in the gastrointestinal tract. From a 2-year chronic toxicity and carcinogenicity study in rats, a NOAEL for systemic toxicity of GO administered via drinking water of 25 mg/kg bw was reported based on reduced body weight and erosions/ulcer in the glandular stomach. Other non-neoplastic and neoplastic lesions were not observed. Acute toxicity of HMF is also low. From a 90-day repeated dose toxicity study in mice, a NOAEL of 94 mg/kg bw was derived based on cytoplasmic alterations of proximal tubule epithelial cells of the kidney. HMF was mostly negative in in vitro genotoxicity tests, although positive findings for mutagenicity were obtained under conditions that promote formation of the chemically reactive sulfuric acid ester 5-sulfoxymethylfurfural. There is some evidence of carcinogenic activity of HMF in female B6C3F1 mice based on increased incidences of hepatocellular adenoma, but not in male mice and rats of both sexes. Although data on oral bioavailability of glycated amino acids are mostly limited to CML, it appears that glycated amino acids may be absorbed from the gastrointestinal tract after oral exposure to their free and protein bound form. Glycated amino acids that are not absorbed in the intestine may be subject to metabolism by the gut microbiome. Glycated amino acids present in the systemic circulation are rapidly eliminated via the urine. Acute oral toxicity of CML is low. Studies in mice and rats reported changes in clinical chemistry parameters indicative of impaired renal and hepatic function. However, these changes were not dose-related and not supported by histopathological evaluation.Previous risk assessments of individual glycation compounds did not identify a health concern at estimated human exposures (GO, HMF) but also noted the lack of data to draw firm conclusions on health risks associated with exposure to MGO.To identify potential associations between dietary intake of defined glycation compounds and disease a systematic review was carried out according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) model, applying the quality criteria previously defined by the SKLM. Using a combination of keywords defining individual glycation compounds and relevant disease patterns linked to the subject area of food, nutrition and diet, a systematic search in Pubmed (Medline), Scopus and Web of Science was performed. Although the present systematic review identified numerous studies that investigated an association between an "AGE-rich diet" and adverse health effects, only a subset of studies was found to comply with the quality criteria defined by the SKLM and was thus considered suitable to assess potential health risks of dietary glycation compounds.For each adverse health effect considered in this assessment, only limited numbers of human studies were identified. Although studies in humans offer the advantage of investigating effects at relevant human exposures, these studies did not provide compelling evidence for adverse effects of dietary glycation compounds. Animal studies identified in this systematic review provide some evidence for induction of impaired glucose tolerance, insulin resistance, cardiovascular effects and renal injury in response to oral exposure to GO and MGO as representatives of dicarbonyl compounds. Only limited evidence points to a link between high intake of glycated amino acids and metabolic disorders. However, these effects were typically reported to occur at dose levels that exceed human dietary exposure, often by several orders of magnitude. Unfortunately, most studies employed only one dose level, precluding characterization of dose-response and derivation of a point of departure for riskassessment. While in vitro studies provide some evidence for a potential mechanistic link between individual glycation compounds and presumed adverse health effects, the clinical and toxicological relevance of the in vitro findings is often limited by the use of high concentrations of glycation compounds that by far exceed human dietary exposure and by insufficient evidence for corresponding adverse effects in vivo. A key question that has not been adequately considered in most studies investigating systemic effects of glycation compounds is the extent of oral bioavailability of dietary glycation compounds, including the form in which MRPs may be taken up (e.g. free vs. peptide bound glycated amino acids). Understanding how much dietary glycation compounds really add to the significant endogenous background is critical to appraise the relevance of dietary MRPs for human health.While it appears mechanistically plausible that glycation of dietary allergens may affect their allergenic potential, the currently available data do not support the hypothesis that dietary glycation compounds may increase the risk for diet-induced allergies. There are no human studies addressing the immunological effects of dietary AGEs. Accordingly, there are no data on whether dietary AGEs promote the development of allergies, nor whether existing allergies are enhanced or attenuated. In numerous in vitro studies, the IgG/E binding ability of antigens and therefore their allergenic potential has been predominantly reported to be reduced by glycation. However, some in vitro studies showed that glycated proteins bind to receptors of immunological cells, and thus may have promoting effects on immune response and inflammation.Although experimental data from animal studies provide some evidence that high doses of individual glycation compounds such as MGO and protein-bound CML may produce certain adverse health effects, including diabetogenic, cardiovascular, metabolic and renal effects, the doses required to achieve these effects by far exceed human dietary exposures. Of note, in the only long-term study identified, a high dose of MGO administered via drinking water to mice for 18 months had no adverse effects on the kidneys, cardiovascular system, or development of diabetes.Experimental data from animal studies provide evidence that high doses of defined glycation compounds such as MGO or protein-bound CML may affect glucose homeostasis. However, the doses required to produce these effects markedly exceed human dietary exposure. Results from human studies are inconclusive: Three short-term intervention studies suggested that diets rich in AGEs may impair glucose homeostasis, whereas one recent intervention study and two observational studies failed to show such an effect.For the cardiovascular system, there is some evidence from in vitro and in vivo studies that high concentrations of MRPs, well above the dietary exposure of humans, may enhance inflammation in the cardiovascular system, induce endothelial damage, increase blood pressure and increase the risk of thrombosis. Only a limited number of human intervention studies investigated potential effects of short-term exposure and longer-term effects of glycation compounds on the cardiovascular system, and yielded inconsistent results. The few observational studies available either found no association between dietary MRP intake and cardiovascular function or even reported beneficial effects. Therefore, currently no definitive conclusion on potential acute and chronic effects of dietary MRPs on inflammation and cardiovascular function can be drawn. However, there is currently also no convincing evidence that potential adverse effects on the cardiovascular system are triggered by dietary MRP intake.Furthermore, human studies did not provide evidence for an adverse effect of dietary MRPs on kidney function. In animal studies with high levels of oral intake, MGO was reported to cause structural and functional effects in the kidney. Several studies show that the concentration of modified proteins and amino acids, such as CML, increases significantly in kidney tissue after oral intake. One study showed a negative effect of a high-temperature-treated diet containing increased CML concentrations on kidney structure integrity and impaired glomerular filtration. The causative relationship of accumulation of dietary MRPs and a functional decline of the kidneys, however, needs further confirmation.With regard to gut health, there is some evidence for alterations in gut microflora composition and the production of individual short-chain fatty acids (SCFAs) upon dietary exposure to glycation compounds. However, this has not been linked to adverse health effects in humans and may rather reflect adaptation of the gut microbiota to changing nutrients. In particular, a human observational study and several animal studies did not find a correlation between the intake of glycation compounds and increased intestinal inflammation. In animal studies, positive effects of glycation compounds on gut tissue damage and dysbiosis during colitis were described.Considering clear evidence for DNA reactivity and genotoxicity of the dicarbonyl compounds GO, MGO and 3-DG, it is plausible to suspect that dicarbonyl compounds may induce mutations and cancer. Although there is some evidence for tumor promoting activity of GO locally in the gastrointestinal tract, the only guideline-compatible chronic rodent bioassays reported erosions and ulcer in the glandular stomach but no treatment-related neoplastic lesions. A recent multinational cohort study with focus on CEL, CML, and MG-H1 found no evidence to support the hypothesis that dietary AGEs are linked to cancer risk.Evidence for an association between human exposure to dietary glycation compounds and detrimental effects on the brain and on cognitive performance is far from being compelling. No human studies fully complying with the defined quality criteria were identified. A few experimental studies reported neuroinflammation and cognitive impairment following dietary MRP exposure, but these can be considered indicative at best and do not support firm conclusions for human health. In addition to utilizing exceedingly high dosages of individual agents like CML, harsh processing conditions causing a multitude of major process-related changes do not allow to convincingly reconcile effects observed with measured/supposed contents of free and protein-bound CML alone.Overall, although dietary glycation compounds have been claimed to contribute to a wide range of adverse health effects, the present critical evaluation of the literature allows the conclusion that the available data are insufficient, inadequate or inconclusive and do not compellingly support the hypothesis of human health risks being related to the presence of glycation compounds in food. The study limitations detailed above, together with the fact that a large number of studies did not comply with the defined quality criteria and therefore had to be excluded highlight the importance of performing adequately designed human or animal studies to inform scientifically reliable health risk assessment.To achieve this, high quality, dependable scientific cooperation within various disciplines is pivotal.

Atmospheric Degradation of Ecologically Important Biogenic Volatiles: Investigating the Ozonolysis of (E)-ß-Ocimene, Isomers of α and ß-Farnesene, α-Terpinene and 6-Methyl-5-Hepten-2-One, and Their Gas-Phase Products.

Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-ß-ocimene, isomers of α and ß-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products.

Exploring Maillard reaction markers and melanoidins to investigate toxicological and antioxidant profiles of optimized expanded snacks from corn/common bean mixtures.

BACKGROUND: Extrusion cooking of cereal-legume flour mixture is an innovative strategy to introduce nutrient-enriched ready-to-eat snacks to the market. However, this thermal process triggers the formation of compounds that could impact safety aspects of these products. Maillard reaction markers and the end products known as melanoidins were evaluated to assess the toxicological and bioactive profiles of extruded snacks from corn-plus-common-bean-flour combinations. Different molecular weight fractions were isolated and purified to analyze their antioxidant activity and to investigate the role of melanoidins. RESULTS: The snack formulated with an 84:16 ratio of corn:common bean flours exhibited an enhanced toxicological profile. It displayed the lowest levels of acrylamide and furanic compounds, along with reduced blockage of lysine residues in the protein. Extrusion increased the antioxidant activity of uncooked flours (30 to 64%) and total phenolic compounds (26 to 50%), and decreased the available lysine (-72.7 to -79.5%). During the fractionation process, it was established that compounds within the range of 3-10 kDa made the greatest contribution to antioxidant activity. The fraction greater than 10 kDa, which included melanoidins, displayed 7 to 33% lower antioxidant activity. The purification of the fraction greater than 10 kDa revealed that pure melanoidins represented approximately one-third of the antioxidant activity in that fraction. Non-covalent adducts linked to the melanoidin core therefore had a relevant role in the antioxidant action of formulated snacks. CONCLUSION: This investigation illustrates the importance of considering both potential risks and associated benefits of compounds formed during the Maillard reaction while developing new extruded snacks. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Anti-oxidant activity of 1-(1H-imidazo[4,5-c]pyridin-4-yl)ethenone, a Maillard reaction product derived from fructose and histidine.

BACKGROUND: The Maillard reaction involves the interaction of various amino acids and reducing sugars, resulting in food browning. It often produces appealing aromas and flavors. The complexities of the reaction are such that it can be challenging to identify the often numerous and frequently volatile products formed by it. In the present study, we sought to identify and evaluate an unusual product with anti-oxidant activity arising from a fructose-histidine Maillard reaction model. The anti-oxidant profile of this product was assessed by computational means. RESULTS: The fructose-histidine Maillard reaction products (FH-MRPs) were generated by heating a 2:1 mixture of the sugar and the amino acid at 140 °C for 2 h. Chromatographically separable fractions, labelled DM-1 to DM-8, were obtained using silica gel as the stationary phase and dichloromethane/methanol (DCM/MeOH) mixtures as the mobile one. Fraction DM-5 exhibited the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and further bio-assay guided fractionation led to isolation and identification of 1-(1H-imidazo[4,5-c]pyridin-4-yl)ethenone (IMPE) as the active principal, the structure of which was established by nuclear magnetic resonance (NMR) spectroscopic and mass spectral techniques. A mechanism for the formation of IMPE from its precursors is proposed. Density functional theory (DFT) calculations suggest this novel heterocyclic compound exerts its anti-oxidant effects by interacting with DPPH and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. Essentially, IMPE was non-toxic below 300 ug mL-1, showing a concentration-dependent free radical clearance capacity and reducing power within the 100-1000 µg mL-1 range, and moreover, exhibiting significant Fe2+ chelating abilities wihin the 50-200 µg mL-1 range. CONCLUSION: This study identified the unique FH-MRP, IMPE, and found that it acts as food antioxidant through the chelation of metal ions. © 2024 Society of Chemical Industry.

Preparation and antimicrobial mechanism of Maillard reaction products derived from ε-polylysine and chitooligosaccharides.

Chitooligosaccharides can be combined with amino acids or polypeptide to form Maillard reaction products (MRPs) with the antibacterial characteristics through Maillard reaction. This research aims to clarify the structure, antimicrobial effect and mechanism against Shewanella putrefaciens (S. putrefaciens) of ε-polylysine and chitooligosaccharides Maillard reaction products (LC-MRPs). The results of intrinsic fluorescence (IF) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction, proton nuclear magnetic resonance (1H NMR) spectra and scanning electron microscope (SEM) indicated Maillard reaction occurred between ε-polylysine and chitooligosaccharides. The observation of confocal laser scanning microscopy (CLSM), SEM and growth curves of S. putrefaciens evidenced that LC-MRPs have the strongest antibacterial effects. The leakage of alkaline phosphatase (AKP) and lactate dehydrogenase (LDH) implied that LC-MRPs sabotaged bacterial barrier (cell wall and cell membrane). The changes in content of nucleic acids, reactive oxygen species (ROS) level, lipid peroxidation content (LPO), succinate dehydrogenase (SDH) activity and adenosine triphosphate (ATP) content showed LC-MRPs will affect bacterial genetic gene transcription, material and energy metabolism. Therefore, the LC-MRPs were effective antibacterial agents to inhibit S. putrefaciens, which will help to preserve food with S. putrefaciens as the main spoilage bacteria.

Mechanisms of action of coffee bioactive compounds - a key to unveil the coffee paradox.

The knowledge of the relationship between the chemical structure of food components with their mechanisms of action is crucial for the understanding of diet health benefits. This review relates the chemical variability present in coffee beverages with the mechanisms involved in key physiological events, supporting coffee as a polyvalent functional food. Coffee intake has been related with several health-promoting properties such as neuroprotective (caffeine, chlorogenic acids and melanoidins), anti-inflammatory (caffeine, chlorogenic acids, melanoidins, diterpenes), microbiota modulation (polysaccharides, melanoidins, chlorogenic acids), immunostimulatory (polysaccharides), antidiabetic (trigonelline, chlorogenic acids), antihypertensive (chlorogenic acids) and hypocholesterolemic (polysaccharides, chlorogenic acids, lipids). Nevertheless, caffeine and diterpenes are coffee components with ambivalent effects on health. Additionally, a large range of potentially harmful compounds, including acrylamide, hydroxymethylfurfural, furan, and advanced glycation end products, are formed during the roasting of coffee and are present in the beverages. However, coffee beverages are part of the daily human dietary healthy habits, configuring a coffee paradox.

The multi-targeted bioactive features of coffee compounds reinforce coffee as a functional food beverage.Polysaccharides and melanoidins positively modulate gut microbiota.Caffeine and phenolics are neuroprotective, anti-inflammatory, antidiabetic and antihypertensive.The balance between potential health and harmful compounds configures a coffee paradox.Harmful compounds are present in trace levels in coffee, not conferring toxicity.

Comprehensive Two-Dimensional Gas Chromatography with Peak Tracking for Screening of Constituent Biodegradation in Petroleum UVCB Substances.

Petroleum substances, as archetypical UVCBs (substances of unknown or variable composition, complex reaction products, or biological substances), pose a challenge for chemical risk assessment as they contain hundreds to thousands of individual constituents. It is particularly challenging to determine the biodegradability of petroleum substances since each constituent behaves differently. Testing the whole substance provides an average biodegradation, but it would be effectively impossible to obtain all constituents and test them individually. To overcome this challenge, comprehensive two-dimensional gas chromatography (GC × GC) in combination with advanced data-handling algorithms was applied to track and calculate degradation half-times (DT50s) of individual constituents in two dispersed middle distillate gas oils in seawater. By tracking >1000 peaks (representing ∼53-54% of the total mass across the entire chromatographic area), known biodegradation patterns of oil constituents were confirmed and extended to include many hundreds not currently investigated by traditional one-dimensional GC methods. Approximately 95% of the total tracked peak mass biodegraded after 64 days. By tracking the microbial community evolution, a correlation between the presence of functional microbial communities and the observed progression of DT50s between chemical classes was demonstrated. This approach could be used to screen the persistence of GC × GC-amenable constituents of petroleum substance UVCBs.

Application of tea polyphenols as additives in brown fermented milk: Potential analysis of mitigating Maillard reaction products.

Brown fermented milk (BFM) is favored by consumers in the dairy market for its unique burnt flavor and brown color. However, Maillard reaction products (MRP) from high-temperature baking are also noteworthy. In this study, tea polyphenols (TP) were initially developed as potential inhibitors of MRP formation in BFM. The results showed that the flavor profile of BFM did not change after adding 0.08% (wt/wt) of TP, and its inhibition rates on 5-hydroxymethyl-2-furaldehyde (5-HMF), glyoxal (GO), methylglyoxal (MGO), Nε-carboxymethyl lysine (CML), and Nε-carboxyethyl lysine (CEL) were 60.8%, 27.12%, 23.44%, 57.7%, and 31.28%, respectively. After 21 d of storage, the levels of 5-HMF, GO, MGO, CML, and CEL in BFM with TP were 46.3%, 9.7%, 20.6%, 5.2%, and 24.7% lower than the control group, respectively. Moreover, a smaller change occurred in their color and the browning index was lower than that of the control group. The significance of this study was to develop TP as additives to inhibit the production of MRP in brown fermented yogurt without changing color and flavors, thereby making dairy products safer for consumers.

Different Regulatory Effects of Heated Products and Maillard Reaction Products of Half-Fin Anchovy Hydrolysates on Intestinal Antioxidant Defense in Healthy Animals.

The oxidative state of intestinal tracts of healthy animals were investigated after short-term intake of half-fin anchovy hydrolysates (HAHp) and their thermal or Maillard reaction products (MRPs). After one month of continuous oral gavage of HAHp, HAHp-heated products (HAHp-H), the MRPs of HAHp with 3% of glucose (HAHp-3%G MRPs), and the MRPs of HAHp with 3% of fructose (HAHp-3%F MRPs) at a dose of 1.0 g/kg of body weight per day into healthy ICR male mice, the concentrations of serum low-density and high-density lipoprotein cholesterol did not significantly change compared to the control group (CK, gavage with saline). Similar results were found for the interleukin-6 concentrations of all groups. By comparison, HAHp-H, HAHp-3%G MRPs, and HAHp-3%F MRPs administration decreased serum tumor necrosis factor-α concentration as compared to the CK group (p < 0.05). No histological damage was observed in the jejunum, ileum, and colonic tissues of all groups. However, HAHp-H treatment induced higher upregulation of Kelch-like ECH-associated protein 1, transcription factors Nrf-2, associated protective phase-II enzymes of NAD(P)H: quinine oxidoreductase-1, and hemoxygenase-1 in colon tissue, as well as higher upregulation of endogenous antioxidant enzymes, including copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, and glutathione peroxidase 2 than other groups (p < 0.05). Additionally, increases in Nε-carboxymethyllysine expression in the colonic tissues of all groups were consistent with their increased oligopeptide transporter 1 expressions. Our results suggest that the thermal products of HAHp might have a broad application prospect in improving antioxidant defense in vivo in healthy animals.

Wheat Roll Enhanced by Buckwheat Hull, a New Functional Food: Focus on the Retention of Bioactive Compounds.

Wheat roll enhanced by buckwheat hull was used as a model for determining the retention of bioactive compounds during technological steps. The research included analysis of the formation of Maillard reaction products (MRPs) and retention of bioactive compounds such as tocopherols, glutathione, or antioxidant capacity. About a 30% decrease in the content of available lysine in the roll was observed compared to the value obtained for fermented dough. Free FIC, FAST index, and browning index were highest for the final products. The increase of analyzed tocopherols (α-, ß-,γ-, and δ-T) was noticed during the technological steps, with the highest values found for the roll with 3% of buckwheat hull. A significant reduction in GSH and GSSG content occurred during the baking process. The observed increase in the value of the antioxidant capacity after the baking process may be the result of the formation of new antioxidant compounds.

Identification and Bioaccessibility of Maillard Reaction Products and Phenolic Compounds in Buckwheat Biscuits Formulated from Flour Fermented by Rhizopus oligosporus 2710.

The identification and potential bioaccessibility of phenolic compounds using the highly sensitive micro-HPLC-QTRAP/MS/MS technique and Maillard reaction products (MRPs) in buckwheat biscuits formulated from flours, raw and roasted, fermented by Rhizopus oligosporus 2710 was addressed in this study after in vitro digestion. The content of the analyzed MRPs such as furosine, FAST index, and the level of melanoidins defined by the browning index was increased in the biscuits prepared from fermented flours as compared to the control biscuits prepared from non-fermented ones. After in vitro digestion higher content of furosine was observed in control and tested biscuits providing its high potential bioaccessibility. The fermented buckwheat flours used for baking affected the nutritional value of biscuits in comparison to the control biscuits in the context of the twice-increased FAST index. More than three times higher value of the browning index was noted in control and tested biscuits after digestion in vitro indicating the high bioaccessibility of melanoidins. Our results showed the presence of ten phenolic acids and eight flavonoids in the investigated biscuits. Among phenolic acids, vanillic, syringic, and protocatechuic were predominant while in the group of flavonoids, rutin, epicatechin, and vitexin were the main compounds in analyzed biscuits. Generally, the lower potential bioaccessibility of phenolic acids and higher potential bioaccessibility of flavonoids was found for biscuits obtained from buckwheat flours fermented by fungi compared to control biscuits obtained from non-fermented flours. Fermentation of buckwheat flour with the fungus R. oligosporus 2710 seems to be a good way to obtain high-quality biscuits; however, further research on their functional properties is needed.

Application of soy protein isolate-xylose conjugates for improving the viability and stability of probiotics microencapsulated by spray drying.

BACKGROUND: Production and consumption of probiotics need to meet many adverse stresses, which can reduce their health-promoting effects on humans. Microencapsulation is an effective technique to improve the biological activity of probiotics and wall materials are also required during encapsulation. Application of Maillard reaction products (MRPs) in probiotic delivery is increasing. RESULTS: This work aims to study the effects of soy protein isolate (SPI)-xylose conjugates heated at different times on the viability and stability of probiotics. SPI-xylose MRPs formed after heat treatment based on changes in the browning intensity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy. After heat treatment, α-helix and ß-sheet contents of SPI-xylose mixture shifted from 11.3% and 31.3% to 6.4-11.0% and 31.0-36.9%, respectively, and the thermal stability slightly changed. During spray drying, except for MRP240@LAB, probiotic viability was higher in the MRP-based probiotic microcapsules (21.36-25.31%) than in Mix0@LAB (20.17%). MRP-based probiotic microcapsules had smaller particle sizes (431.1-1243.0 nm vs. 7165.0 nm) and greater intestinal digestion tolerance than Mix0@LAB. Moreover, the MRP-based probiotic microcapsules showed better storability than Mix0@LAB and adequate growth and metabolism capacity. CONCLUSION: SPI-xylose Maillard reaction products are a promising wall material for probiotics microencapsulation, which can improve bacterial survivability during spray drying and enhance bacterial gastrointestinal digestion resistance. This study sheds light on preparing probiotic microcapsules with superior properties by spray drying. © 2023 Society of Chemical Industry.

Effects of ε-polylysine and chitooligosaccharide Maillard reaction products on quality of refrigerated sea bass fillets.

BACKGROUND: The Maillard reaction is a promising and safe method for obtaining chitooligosaccharide conjugates with proteins or peptides as food preservatives. This study aims to investigate the moisture state, physicochemical properties, and shelf-life of sea bass fillets treated with ε-polylysine (ε-PL) and chitooligosaccharides (COS), which are Maillard reaction products (LC-MRPs), during refrigerated storage. RESULTS: The results of microbiological analysis and confocal laser scanning microscope (CLSM) revealed that LC-MRPs could retard microbial growth effectively. Compared with control, other treated groups could strongly retard the increase in the thiobarbituric acid (TBA) value, the K-value and the total volatile basic nitrogen (TVB-N) value, and also inhibited the softening of texture and the accumulation of biogenic amines in fish. The results of low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) indicate that LC-MRPs could delay the water migration of fillets and increase water holding capacity (WHC). Through sensory evaluation, the application of LC-MRPs increased the shelf-life of refrigerated sea bass fillets for another 9 days. CONCLUSION: Maillard reaction products derived from chitooligosaccharides and ε-polylysine have strong potential for preserving sea bass. © 2022 Society of Chemical Industry.

Optimisation of Manganese Peroxidase (MnP) Activity of Enterobacter wuhouensis Using Response Surface Method and Evaluation of Its Maillard Reaction Products Along with Lignin Degradation Ability.

Manganese peroxidase (MnP), a microbial ligninolytic enzyme which plays significant role in lignin and melanoidin degradation has gained much attention in the field of industry. In the present study, 15 ligninolytic bacteria were isolated from the soil sample of Similipal Biosphere Reserve (SBR) and screened for MnP activity. The most efficient MnP-producing bacterium HNB5 was evaluated for alkali lignin and maillard reaction products (MRPs) degradation and identified as Enterobacter wuhouensis using 16S rRNA sequencing. This bacterium exhibited the highest MnP activity of 2.6 U mL-1 min-1 in un-optimized conditions. Further, optimization using response surface methodology E. wuhouensis showed increased MnP activity of 4.11 U mL-1 min-1 at pH 6.3, temperature 37 °C, substrate concentration 1.05%, and time 144 h. In both FT-IR and UV-Vis spectrophotometry analyses of control and bacterium degraded MRPs, the reduction in Maillard product colour was correlated with shifting absorption peaks. Also, the GC-MS analysis data showing a change in functional group revealed the rise of novel peaks caused due to the degradation of MRPs complex. The phytotoxicity study was conducted for bacterial degraded MRPs medium revealed that toxicity of the medium decreased after bacterial treatment. The findings of the current study suggest that the manganese MnP produced by E. wuhouensis isolated from SBR soil sample may be employed for bioremediation purposes to degrade MRPs.

Improvements of plant protein functionalities by Maillard conjugation and Maillard reaction products.

Plant-derived protein research has gained attention in recent years due to the rise of health concerns, allergenicity, trends toward vegan diet, food safety, and sustainability; but the lower techno-functional attributes of plant proteins compared to those of animals still remain a challenge for their utilization. Maillard conjugation is a protein side-chain modification reaction which is spontaneous, and do not require additional chemical additive to initiate the reaction. The glycoconjugates formed during the reaction significantly improves the thermal stability and pH sensitivity of proteins. The modification of plant-derived protein using Maillard conjugation requires a comprehensive understanding of the influence of process conditions on the conjugation process. These factors can be used to establish a correlation with different functional and bioactive characteristics, to potentially adapt this approach for selective functionality enhancement and nutraceutical development. This review covers recent advances in plant-derived protein modification using Maillard conjugation, including different pretreatments to modify the functionality and bioactivity of plant proteins and their potential uses in practice. An overview of different properties of conjugates and MRPs, including food safety aspects, is given.

Foliar Application of Reaction Products Derived from Selenite Removal by Iron Monosulfide for Brassica rapa ssp. Chinensis L.

The extensive application of FeS in environmental remediation requires the recovery and reuse of reaction products between FeS and pollutants. Therefore, foliar application of reaction products derived from selenite [Se(IV)] removal by FeS for pak choi was performed. The removal rate of Se(IV) by 100 mg/L FeS was 0.047 h-1. 93.2% of Se(IV) was reduced to Se(0), and FeS was correspondingly oxidized to goethite (78.9%), lepidocrocite (21.1%), and S(0) (91.5%) based on the analysis of X-ray absorption fine structure. The reaction products promoted the growth of pak choi in terms of fresh biomass, vitamin C, and protein, ascribed to the key roles of Fe and S in enhancing the electron transfer rate and light conversion rate. Furthermore, the application of reaction products decreased by 64% of disease incidence as compared with the pathogen Pseudomonas syringae pv. maculicola-infected control. The total Se content in plants increased to 576 µg/kg and was composed of 11.9% of SeMeCys, 29.8% of SeMet, and 58.3% of SeCys after exposure to reaction products, which is beneficial to the human dietary intake from pak choi. This study demonstrated that the reaction products between FeS and Se(IV) could be recovered and applied as a nano-enabled strategy to prevent crop insecurity.

Unveiling the pH-Dependent Yields of H2O2 and OH by Aqueous-Phase Ozonolysis of m-Cresol in the Atmosphere.

Hydrogen peroxide (H2O2) and hydroxyl radical (OH) are important oxidants in the atmospheric aqueous phase such as cloud droplets and deliquescent aerosol particles, playing a significant role in the chemical transformation of organic and inorganic pollutants in the atmosphere. Atmospheric aqueous-phase chemistry has been considered to be a source of H2O2 and OH. However, our understanding of the mechanisms of their formation in atmospheric waters is still incomplete. Here, we show that the aqueous-phase reaction of dissolved ozone (O3) with substituted phenols such as m-cresol represents an important source of H2O2 and OH exhibiting pH-dependent yields. Intriguingly, the formation of H2O2 through the ring-opening mechanism is strongly promoted under lower pH conditions (pH 2.5-3.5), while higher pH favors the ring-retaining pathways yielding OH. The rate constant of the reaction of O3 with m-cresol increases with increasing pH. The reaction products formed during the ozonolysis of m-cresol are analyzed by an Orbitrap mass spectrometer, and reaction pathways are suggested based on the identified product compounds. This study indicates that aqueous-phase ozonolysis of phenolic compounds might be an alternative source of H2O2 and OH in the cloud, rain, and liquid water of aerosol particles; thus, it should be considered in future model studies.

Application of Maillard Reaction Products Derived Only from Enzymatically Hydrolyzed Sesame Meal to Enhance the Flavor and Oxidative Stability of Sesame Oil.

The low-temperature roasting of sesame oil has become increasingly popular because of its nutritional benefits; however, the flavor is reduced. In order to improve the quality of sesame oil without exogenous addition, sesame meal was hydrolyzed and further used to prepare Maillard reaction products (MRPs) while protease hydrolysis (PH) and glucoamylase-protease hydrolysis (GPH) were used, and their respective Maillard products (PHM and GPHM) were added in the oils for reducing sugar and total sugar content determination, free amino acid determination, and color and descriptive sensory analysis, as well as electronic nose, SPME-GC-MS, odor activity value, and oxidative stability analyses. Results showed that the MRPs could be produced using the enzymatically hydrolyzed sesame meal without exogenous addition, and the oil flavor blended with GPHM (GPHM-SO) was significantly (p < 0.05) improved with the best sensory quality. The composition of pyrazines (119.35 µg/mL), furans (13.95 µg/mL), and sulfur substances (6.25 µg/mL) contributed positively to sensory properties in GPHM-SO, and 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, and 2,3-dimethylpyrazine were characterized as the key flavor compounds with odor activity values of 7.01, 14.80, and 31.38, respectively. Furthermore, the oxidative stability of the oil was significantly improved with the addition of MRPs, and the shelf life of GPHM-SO was predicted to be extended by 1.9 times more than that of the crude oil based on the accelerated oxidation fitting analysis. In general, the MRPs derived only from sesame meal can enhance the flavor and oxidative stability of sesame oil and can be applied in the oil industry.

Mechanism, Kinetics and Thermodynamics of Decomposition for High Energy Derivatives of [1,2,4]Triazolo[4,3-b][1,2,4,5]tetrazine.

This paper presents the data of research studies on the mechanisms, kinetics and thermodynamics of decomposition of three high-energy compounds: [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine-3,6-diamine (TTDA), 3-amino-6-hydrazino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine (TTGA) and 3,6-dinitroamino[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine (DNTT). The points of change of the reaction mechanisms under thermal effects with different intensities from 0.1 to 2000 s-1 have been established. The values of activation and induction energies for the limiting stages of decomposition have been obtained. The formation of nanostructured carbon nitride (α-C3N4) in condensed decomposition products, cyanogen (C2N2) and hydrogen cyanide (HCN) in gaseous products have been shown. Concentration-energy diagrams for the reaction products have been compiled. The parameters of heat resistance and thermal safety proved to be: 349.5 °C and 358.2 °C for TTDA; 190.3 °C and 198.0 °C for TTGA; 113.4 °C and 114.1 °C for DNTT. The energy and thermodynamic properties have also been estimated. This work found the activation energy of the decomposition process to be 129.0 kJ/mol for TTDA, 212.2 kJ/mol for TTGA and 292.2 kJ/mol for DNTT. The average induction energy of the catalytic process (Ecat) for TTGA was established to be 21 kJ/mol, and for DNTT-1500-1700 kJ/mol. The induction energy of the inhibition process (Eing) of TTDA was estimated to be 800-1400 kJ/mol.

Endogenous Synthesis of Tetrahydroisoquinoline Derivatives from Dietary Factors: Neurotoxicity Assessment on a 3D Neurosphere Culture.

Tetrahydroisoquinoline (THIQ) alkaloids and their derivatives have a structural similarity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a well-known neurotoxin. THIQs seem to present a broad range of actions in the brain, critically dependent on their catechol moieties and metabolism. These properties make it reasonable to assume that an acute or chronic exposure to some THIQs might lead to neurodegenerative diseases including essential tremor (ET). We developed a method to search for precursor carbonyl compounds produced during the Maillard reaction in overcooked meats to study their reactivity with endogenous amines and identify the reaction products. Then, we predicted in silico their pharmacokinetic and toxicological properties toward the central nervous system. Finally, their possible neurological effects on a novel in vitro 3D neurosphere model were assessed. The obtained data indicate that meat is an alkaloid precursor, and we identified the alkaloid 1-benzyl-1,2,3,4-tetrahydroisoquinoline-6,7-diol (1-benz-6,7-diol THIQ) as the condensation product of phenylacetaldehyde with dopamine; in silico study of 1-benz-6,7-diol-THIQ reveals modulation of dopamine receptor D1 and D2; and in vitro study of 1-benz-6,7-diol-THIQ for cytotoxicity and oxidative stress induction does not show any difference after 24 h contact for all tested concentrations. To conclude, our in vitro data do not support an eventual neurotoxic effect for 1-benz-6,7-diol-THIQ.