Investigating the Formation of In Vitro Immunogenic Gluten Peptides after Covalent Modification of Their Structure with Green Tea Phenolic Compounds under Alkaline Conditions.

Celiac disease is an autoimmune disorder triggered by immunogenic gluten peptides produced during gastrointestinal digestion. To prevent the production of immunogenic gluten peptides, the stimulation of covalent-type protein-polyphenol interactions may be promising. In this study, gluten interacted with green tea extract (GTE) at pH 9 to promote the covalent-type gluten-polyphenol interactions, and the number of immunogenic gluten peptides, 19-mer, 26-mer, and 33-mer, was monitored after in vitro digestion. Treatment of gluten with GTE provided an increased antioxidant capacity, decreased amino group content, and increased thermal properties. More importantly, there was a remarkable (up to 73%) elimination of immunogenic gluten peptide release after the treatment of gluten with 2% GTE at 50 °C and pH 9 for 2 h. All of these confirmed that gluten was efficiently modified by GTE polyphenols under the stated conditions. These findings are important in developing new strategies for the development of gluten-free or low-gluten food products with reduced immunogenicity.

Role of curcumin in the conversion of asparagine into acrylamide during heating.

This study aimed to investigate the ability of curcumin to convert asparagine into acrylamide during heating at different temperatures. Binary and ternary model systems of asparagine-curcumin and asparagine-curcumin-fructose were used to determine the role of curcumin on acrylamide formation in competitive and uncompetitive reaction conditions. The results indicated that curcumin could potentially contribute to acrylamide formation under long-term heating conditions as long as asparagine was present in the medium. The amount of acrylamide formed in the ternary system was slightly higher than in the binary system during heating (p < 0.05), because of the higher concentrations of carbonyl compounds initially available. The kinetic trends were similar in both model systems evidencing that fructose reacted with asparagine more rapidly than curcumin. The data reveal that acrylamide formation in the temperature range of 150-200°C obeys Arrhenius law with activation energy of 79.1 kJ/mole. Data of this work showed the possibility that antioxidants having a carbonyl compound can react directly with ASN leading to acrylamide. The addition of antioxidants to foods may increase the formation of acrylamide upon long-term heating if free sugar concentration is low and ASN concentration is relatively high.

Casein-phenol interactions occur during digestion and affect bioactive peptide and phenol bioaccessibility.

Casein (CN) represents many proline residues that may bind polyphenols. Some evidence exists of CN-polyphenols interaction in model systems. The formation of such interactions upon digestion and the effects on CN digestibility and potential functionality due to the release of bioactive peptides are obscure. This study aimed to explore the interactions of CN with different phenol compounds under digestive conditions and monitor how they affect the bioaccessibility of phenol compounds and bioactive peptides. CN or CN hydrolysate and phenol compounds such as chlorogenic acid, ellagic acid, catechin, green tea extract, and tea extract, singularly or in combination with CN were digested in vitro. Total antioxidant capacity (TAC), degree of hydrolysis, and bioactive peptide formation were assessed in the samples collected through the digestion. The results showed that bioaccessible TAC was 1.17 to 1.93-fold higher in CN co-digested with phenol compounds than initially due to a higher release of antioxidant peptides in the presence of phenolic compounds. However, TAC values in the intestinal insoluble part of CN-phenol digests were higher than the initial, indicating that such interactions may be functional to transport phenols to the colon. Bioactive peptide release was affected by the phenol type (catechins were the most effective) as well as phenol concentration. As an opioid peptide released from ß-CN, ß-casomorphin formation was significantly influenced by the co-digestion of CN with phenol compounds. This study confirmed the possible CN-phenol interaction during digestion, affecting bioactive peptide release.

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.

Acrylamide in Corn-Based Thermally Processed Foods: A Review.

Widely consumed thermally processed corn-based foods can have a great contribution to acrylamide dietary intake, thus bearing a high public health risk and requiring attention and application of strategies for its reduction. This paper reviews the literature on the acrylamide content of corn-based food products present in the market around the world. The potential of corn for acrylamide formation due to its content of free asparagine and reducing sugars is described. Human exposure to acrylamide from corn-based foods is also discussed. The content of acrylamide in corn/tortilla chips, popcorn, and corn flakes, as widely consumed products all over the world, is reported in the literature to be between 5 and 6360 µg/kg, between

5-Hydroxymethylfurfural accumulation plays a critical role on acrylamide formation in coffee during roasting as confirmed by multiresponse kinetic modelling.

This study aims to investigate in depth the mechanism of acrylamide formation in coffee during roasting. For this purpose, a comprehensive kinetic model including the elementary steps for acrylamide formation was proposed. The changes in sucrose, reducing sugars, free amino acids, asparagine, acrylamide, 3-deoxyglucosone, methylglyoxal, glyoxal, and 5-hydroxymethylfurfural were monitored in coffee during roasting at 200, 220 and 240 °C. Dominant pathways of complex reactions leading to acrylamide were unravelled by means of multiresponse kinetic modelling approach. The results of the model indicated that sucrose degrades into glucose and a reactive fructofuranosyl cation. Interestingly, glucose takes part mostly in the formation of intermediates, glyoxal and especially 3-deoxyglucosone rather than acrylamide formation. On the other hand, fructofuranosyl cation contributed mostly to the formation of 5-hydroxymethylfurfural which was found to be the most important intermediate precursor of acrylamide formed in coffee during roasting.

Investigations on the Maillard Reaction in Sesame ( Sesamum indicum L.) Seeds Induced by Roasting.

This study investigated the formation of Maillard reaction products in sesame seeds under different roasting conditions. Sesame seeds were roasted at 150, 180, 200, and 220 °C for 10 min, and thermal process contaminants including 5-hydroxymethylfurfural, acrylamide, furan, and dicarbonyl compounds (1-deoxyglucosone, 3-deoxyglucosone, methylglyoxal, and diacetyl) together with glycation markers namely N-ε-fructosyllysine, N-ε-carboxymethyllysine, and N-ε-carboxyethyllysine, were monitored. Roasting induced the formation of 5-hydroxymethylfurfural, acrylamide, and dicarbonyl compounds, except furan, significantly ( p < 0.05). 5-Hydroxymethylfurfural and acrylamide content of roasted sesame seeds were found to vary as 3-40 mg/kg and 135-633 µg/kg, respectively. Dicarbonyl compounds were in the following order: methylglyoxal > 3-deoxyglucosone > 1-deoxyglucosone > diacetyl. On the other hand, N-ε-fructosyllysine concentration decreased while the roasting temperature increased; however, N-ε-carboxymethyllysine and N-ε-carboxyethyllysine formation was induced under those conditions. This is the first study reporting the formation of thermal process contaminants and glycation markers in sesame seeds through Maillard reaction during roasting.

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

In this study, reactions of hydroxymethylfurfural (HMF) with selected amino acids (arginine, cysteine and lysine) were investigated in HMF-amino acid (high moisture) and Coffee-amino acid (low moisture) model systems at 5, 25 and 50°C. The results revealed that HMF reacted efficiently and effectively with amino acids in both high and low moisture model systems. High-resolution mass spectrometry (HRMS) analyses of the reaction mixtures confirmed the formations of Michael adduct and Schiff base of HMF with amino acids. Calculated pseudo-first order reaction rate constants were in the following order; kCysteine>kArginine>kLysine for high moisture model systems. Comparing to these rate constants, the kCysteine decreased whereas, kArginine and kLysine increased under the low moisture conditions of Coffee-amino acid model systems. The temperature dependence of the rate constants was found to obey the Arrhenius law in a temperature range of 5-50°C under both low and high moisture conditions.

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

This study investigated the possible formation and elimination reactions of 5-hydroxymethylfurfural (HMF) with amino and sulfhydryl groups in commercial biscuits during simulated in vitro gastrointestinal digestion. At the end of gastric phase, significant increase was observed in HMF contents of biscuits (p<0.05). By high-resolution mass spectrometry (HRMS) analysis, it was confirmed that sugar dehydration products such as 3-deoxyglucosone and 3,4-dideoxyglucosone accumulated in biscuits during baking were converted to HMF under gastric conditions. However, reactions of HMF with amino acids proceeded with the progress of digestion. HRMS analysis in both HMF-amino acid model systems and in biscuits confirmed that formed HMF reacted with amino and sulfhydryl groups through Michael type addition. In addition, formation of Schiff base during intestinal phases led to a significant decrease in the concentrations of HMF (p<0.05).

Inhibitory effect of hawthorn extract on heterocyclic aromatic amine formation in beef and chicken breast meat.

This study focused on the inhibitory effect of different levels of hawthorn extract (0, 0.5, and 1%) on the formation of heterocyclic aromatic amines (HAAs) in beef and chicken breast cooked by either pan-cooking or oven-cooking. All meat samples were cooked at three different temperatures (150, 200, and 250°C) and the levels of twelve HAAs were assessed (IQ, IQx, MeIQ, MeIQx, 4,8-DiMeIQx, 7,8-DiMeIQx, PhIP, harman, norharman, AαC, MeAαC, and Trp-P-2). Varying levels of IQ (up to 4.47ng/g), IQx (up to 0.69ng/g), MeIQ (up to 0.82ng/g), MeIQx (up to 1.01ng/g), 4,8-DiMeIQx (up to 0.10ng/g), 7,8-DiMeIQx (up to 0.23ng/g), PhIP (up to 0.75ng/g), harman (up to 2.15ng/g), norharman (up to 1.08ng/g), AαC (up to 1.86ng/g), MeAαC (up to 0.48ng/g), and Trp-P-2 (up to 12.88ng/g), were detected. Samples cooked at 150°C had very low amounts of HAAs, and the levels of HAAs increased gradually when the cooking temperature rose from 150 to 250°C. The total HAA content in chicken breast and beef ranged between not detectable to 17.60ng/g, and not detectable to 11.38ng/g, respectively. The inhibitory effects of hawthorn extract at 0.5% and 1% on total HAAs levels were found to be 12-100% and 19-97% in chicken breast, respectively, and 42-100% and 20-35% in beef, respectively. This study demonstrated that hawthorn extracts at 0.5% and 1% could mitigate HAA formation, especially at high cooking temperatures.

Investigations on the reactions of α-dicarbonyl compounds with amino acids and proteins during in vitro digestion of biscuits.

This study investigated the interactions of reactive α-dicarbonyl compounds, particularly methylglyoxal (MGO) and 3-deoxyglucosone (3-DG), in commercial biscuits during gastrointestinal digestion. An in vitro multi-step enzymatic digestion system simulating gastric, duodenal and colon phases was used. MGO and 3-DG concentrations decreased with the progress of digestion. Model systems composed of MGO and lysine, cysteine or ovalbumin and model biscuits containing lysine, cysteine or ovalbumin were subjected to in vitro digestion. The results revealed that disappearance in dicarbonyl contents was due to interactions of reactive dicarbonyl compounds with the accumulating amino acids during digestive process. By a high resolution mass spectrometry analysis in model systems and biscuits, the formation of adducts of dicarbonyl compounds with amino or sulfhydryl groups of amino acids was confirmed.

Investigation of the reactions of acrylamide during in vitro multistep enzymatic digestion of thermally processed foods.

This study investigated the fate of acrylamide in thermally processed foods after ingestion. An in vitro multistep enzymatic digestion system simulating gastric, duodenal and colon phases was used to understand the fate of acrylamide in bakery and fried potato products. Acrylamide levels gradually decreased through gastric, duodenal and colon phases during in vitro digestion of biscuits. At the end of digestion, acrylamide reduction was between 49.2% and 73.4% in biscuits. Binary model systems composed of acrylamide and amino acids were used to understand the mechanism of acrylamide reduction. High-resolution mass spectrometry analyses confirmed Michael addition of amino acids to acrylamide during digestion. In contrast to bakery products, acrylamide levels increased significantly during gastric digestion of fried potatoes. The Schiff base formed between reducing sugars and asparagine disappeared rapidly, whereas the acrylamide level increased during the gastric phase. This suggests that intermediates like the Schiff base that accumulate in potatoes during frying are potential precursors of acrylamide under gastric conditions.

In depth study of acrylamide formation in coffee during roasting: role of sucrose decomposition and lipid oxidation.

Coffee, as a source of acrylamide, needs to be investigated in depth to understand the contribution of different precursors. This study aimed to investigate the contributions of sucrose decomposition and lipid oxidation on acrylamide formation in coffee during roasting. Coffee beans and model systems were used to monitor the accumulation of neo-formed carbonyls during heating through sucrose decomposition and lipid oxidation. High resolution mass spectrometry analyses confirmed the formation of 5-hydroxymethylfurfural (HMF) and 3,4-dideoxyosone, which were identified as the major sugar decomposition products in both roasted coffee and model systems. Among others, 2-octenal, 2,4-decadienal, 2,4-heptadienal, 4-hydroxynonenal, and 4,5-epoxy-2-decenal were identified in relatively high quantities in roasted coffee. Formation and elimination of HMF in coffee during roasting had a kinetic pattern similar to those of acrylamide. Its concentration rapidly increased within 10 min followed by an exponential decrease afterward. The amount of lipid oxidation products tended to increase linearly during roasting. It was concluded from the results that roasting formed a pool of neo-formed carbonyls from sucrose decomposition and lipid oxidation, and they play certain role on acrylamide formation in coffee.