Moisture Property and Thermal Behavior of Two Novel Synthesized Polyol Pyrrole Esters in Tobacco

To overcome the shortcomings of high relative humidity and harmful oxidation products from traditional humectants, excellent humectants and flavor precursors were reported herein. Glucosamine hydrochloride was used as the starting material for the cyclization, oxidation, and alkylation processes that produced pyrrole acid. Then, esterification occurred with polyol catalyzed by EDC and DMAP to give the target compounds 2-(2,3-dihydroxypropyl) 4-methyl 5-methyl-1-propyl-1H-pyrrole-2,4-dicarboxylate (Gpe) and (2-hydroxypropyl) 4-methyl 5-methyl-1-propyl-1H-pyrrole-2,4-dicarboxylate (Ppe). Nuclear magnetic resonance (¹H NMR, ¹³C NMR), infrared spectroscopy (IR), and high-resolution mass recorded spectrometry (HRMS) were used to confirm the two novel polyol pyrrole ester compounds. When Gpe and Ppe were added to the tobacco shred, low-field nuclear magnetic resonance (LF-NMR) imaging was applied to assess the hygroscopicity and moisturizing capacity. Furthermore, thermogravimetry (TG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques were applied to study their thermal behaviors. These results showed that the target compounds (Gpe and Ppe) are good humectants with thermal properties of high-temperature stability and flavor release.

Occurrence of Furfural and Its Derivatives in Coffee Products in China and Estimation of Dietary Intake

This is the first report on the content of furfural and its derivatives in coffee products in China. The concentrations of furfural and its derivatives in 449 sampled, commercially available coffee products in China were analyzed through a GC-MS technique, and the associated health risks were estimated. As a result, 5-hydroxymethyl furfural (5-HMF) was identified as the predominant derivative compound, with the highest concentration of 6035.0 mg/kg and detection frequency of 98.7%. The mean dietary exposures of 5-HMF, 5-MF(5-methylfurfural), and 2-F(2-furfural) in coffee products among Chinese consumers were 55.65, 3.00, and 3.23 μg/kg bw/day, respectively. The ranges of mean dietary intake of furfural and its derivatives based on age groups were all lower than the acceptable daily intake (ADI) and the toxicological concern threshold (TTC). Risk evaluation results indicate that coffee product intake did not pose potential risks to consumers. Notably, the analysis revealed that children aged 3-6 years had the highest mean exposure due to their low body weight.

Structural characterization of polar melanoidins deriving from Maillard reaction intermediates - A model approach

Chemical conversions of reducing sugars and amino compounds induce the formation of heterogenous, high-molecular-weight colorants ('melanoidins') with widely unknown chemical structures. Model experiments of reactive intermediates have proven to be suitable for unravelling the formation mechanisms of colored reaction products. Here, the active methylene norfuraneol was selected and incubated individually as well as in combination with glyoxal, glycolaldehyde, and acetaldehyde at elevated temperatures. Photometric and chromatographic methods as well as mass spectrometry were used to analyze the colored reaction products and reveal the reactivity of different carbonyls regarding the formation of heterogenous oligomers. Aqueous solutions of norfuraneol and glyoxal exceeded the color formation of all other model reaction systems and it could be shown that the initial reactants as well as their degradation products were incorporated into the colorants. The colored oligomers described herein were composed of carbohydrate-based intermediates of the Maillard reaction and defined as melanoidin precursors or pre-melanoidins.

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.

Study on the reduction of heterocyclic amines by marinated natural materials in pork belly

This study was conducted to determine the effect of natural ingredient seasoning on the reduction of heterocyclic amine (HCA) production that may occur when pork belly is cooked at a very high temperature for a long time. Pork belly seasoned with natural ingredients, such as natural spices, blackcurrant, and gochujang, was cooked using the most common cooking methods, such as boiling, pan fry, and barbecue. HCAs in pork belly were extracted through solid-phase extraction and analyzed via high-performance liquid chromatography. For short-term toxicity, a mouse model was used to analyze weight, feed intake, organ weight, and length; hematology and serology analysis were also performed. Results revealed that HCAs formed only when heating was performed at a very high temperature for a long time, not under general cooking conditions. Although the toxicity levels were not dangerous, the method showing the relatively highest toxicity among various cooking methods was barbecue, and the natural material with the highest toxicity reduction effect was blackcurrant. Furthermore, seasoning pork belly with natural materials containing a large amount of antioxidants, such as vitamin C, can reduce the production of toxic substances, such as HCAs, even if pork belly is heated to high temperatures.

Vinegar Volatile Organic Compounds: Analytical Methods, Constituents, and Formation Processes

Vinegar is an acid condiment shared all over the world. According to the raw materials, vinegar can be mainly divided into fruit and cereal ones, both of which possess unique aroma and flavor characteristics and corresponding volatile organic compounds (VOCs). Many studies about vinegar VOCs' (VVOCs) sorts, analytical methods, and forming mechanisms have been done. In this review, the main categories of vinegar and their distribution in the world are briefly introduced, then VVOCs' analytical and identified methods, types, and forming processes are summarized. Additionally, the VVOCs' research directions are discussed and prospected. According to the searched literatures, this study is the first to systematically review the analytical methods, sorts, and formation mechanisms of VVOCs, which will make the readers better understand the vinegar's aromas and flavors and their producing mechanisms.

Analysis of the Formation of Sauce-Flavored Daqu Using Non-targeted Metabolomics

Sauce-flavored Daqu exhibits different colors after being stacked and fermented at high temperatures. Heiqu (black Daqu, BQ) with outstanding functions is difficult to obtain because its formation mechanism is unclear. In this study, we compared the metabolites in different types of Daqu using ultra-high-performance liquid chromatography triple quadrupole mass spectrometry to explore the formation process of BQ. We found that 251 differential metabolites were upregulated in BQ. Metabolic pathway analysis showed that "tyrosine metabolism" was enriched, and most metabolites in this pathway were differential metabolites upregulated in BQ. The tyrosine metabolic pathway is related to enzymatic browning and melanin production. In addition, the high-temperature and high-humidity fermentation environment of sauce-flavored Daqu promoted an increase in the melanoidin content via a typical Maillard reaction; thus, the melanoidin content in BQ was much higher than that in Huangqu and Baiqu. By strengthening the Maillard reaction precursor substances, amino acids, and reducing sugars, the content of Daqu melanoidin increased significantly after simulated fermentation. Therefore, the enzymatic browning product melanin and Maillard reaction product melanoidin are responsible for BQ formation. This study revealed the difference between BQ and other types of Daqu and provides theoretical guidance for controlling the formation of BQ and improving the quality of liquor.

Combined Urinary Biomarkers to Assess Coffee Intake Using Untargeted Metabolomics: Discovery in Three Pilot Human Intervention Studies and Validation in Cross-Sectional Studies

Coffee is a widely consumed beverage worldwide and has a high content of chlorogenic acids, polyphenols, methylxanthines, and volatile flavor compounds. Scientific evidence to support the beneficial health effects of coffee is limited, and validated urinary biomarkers of coffee intake are therefore needed. We observed 23 common putative biomarkers of coffee intake in three separate parallel intervention studies by ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (UHPLC-ESI-QTOF-MS) and multivariate analyses. Baseline samples from the NU-AGE study were used to confirm and validate 16 of these candidate biomarkers, including their robustness, time response, and dose response. These validated candidate biomarkers are N-methylpyridinium cation, 1-methyl-1H-pyrrole-2-carboxaldehyde, 1H-pyrrole-2-carboxaldehyde sulfate, 3-piperidinemethanol, furfurylidene-furfurylamine, 2-furoylglycine, N-substituted-5-(aminoethyl) furan-2-carbaldehyde derivative, 3',4'-dihydroxyacetophenone sulfate, caffeine, dihydroxystyrene glucuronide, ferulic acid sulfate, 4-ethylcatechol glucuronide, 3-feruloylquinic acid, 3,4-dihydroxystyrene sulfate, one unknown glucuronide, and one unknown sulfate. Combinations of candidate biomarkers gave a better prediction of coffee consumption than individual biomarkers. The robustness of the combined biomarkers requires additional validation in cohort studies covering other populations.

Sensory and Chemical Characteristic of Two Insect Species: Tenebrio molitor and Zophobas morio Larvae Affected by Roasting Processes

The volatile compounds from insects (Tenebrio molitor and Zophobas morio larvae) roasted at 160, 180, or 200 °C and fed with potato starch or blue corn flour were isolated by solid-phase microextraction (SPME), and identified by gas chromatography–mass spectrometry (GC-MS). In the tested material, 48 volatile compounds were determined. Among them, eight are pyrazines, aroma compounds that are formed in food products during thermal processing due to the Maillard reaction. Eleven of the identified compounds influenced the roast, bread, fat, and burnt aromas that are characteristic for traditional baked dishes (meat, potatoes, bread). Most of them are carbonyl compounds and pyrazines. To confirm the contribution of the most important odorants identified, their odor potential activity values (OAVs) and %OAV were calculated. The highest value was noted for isobuthylpyrazine, responsible for roast aroma (%OAV > 90% for samples roasted at lower temperatures), and 2,5-dimethylpyrazine, responsible for burnt aroma (%OAV > 20% for samples roasted at the highest temperature). According to the study, the type of feed did not significantly affect the results of the sensory analysis of roasted insects. The decisive influence was the roasting temperature. The highest scores were achieved for Tenebrio molitor larvae heat-treated at 160 °C.

Effects of roasting level on physicochemical, sensory, and volatile profiles of soybeans using electronic nose and HS-SPME-GC-MS

We applied oven-roasting on soybean in order to investigate their physicochemical, sensory, and volatile profiles using electronic nose and HS-SPME-GC-MS. Results revealed a temperature dependent kinetic on the physicochemical index except fat content. Roasting at 200 °C for 20 min decreased the protein dispersibility index about 38%; while, lipoxygenase and peroxidase were entirely inactivated. The primary heat sensitive amino acids were methionine, arginine, and cysteine. Electronic nose showed certain capacity to discriminate varying roasted soybeans. Out of 41 volatile compounds identified in soybean headspace, 2,5-dimethylpyrazine showed the highest abundance of 411.18 μg/Kg. Regression model suggested the association of hexanal and aliphatic alcohols with beany flavor, while pyrazines, heterocycles, and furanoids showed a positive correlation with roasted flavor. The selected flavor markers can be used to predict the development of flavor in roasted soybeans. Our study emphasized the effect of roasting level on nutritive value and flavor profiles of soybeans.

Issues surrounding consumer trust and acceptance of existing and emerging food processing technologies

The purpose of food processing today is to make food safer, more nutritious and tastier, and to increase storage life. Consumers have a lack of trust in the way food is produced, formulated and processed, particularly with possible contaminants or chemical residues from production. Food manufacturers are not seen as being highly trusted sources. This may partly result from manufacturers' reluctance to share all information and to protect intellectual property via patents and thus maintain a competitive edge. There is a need to inform the consumer better about what operations the involved ingredients are subjected to and why. Various ways of food processing are reviewed. New food processing technologies face challenges when introduced and factors influencing consumers' and other stakeholders' acceptance should be part of decision-making process when adopting new technologies. Consumers' perception of risks is not the same as the risk assessment made by experts. A few specific cases are being discussed to further highlight the multiplicity of factors that may contribute to the development of a certain consumer perception about a product or a class of products. This is also linked to the emergence of certain terminologies that are associated with an increasingly negative perception of the processing of foods. We recommend more transparency on food formulation and food processing to restore consumer trust, which enables to take the advantage of the benefits different processing methods offer. Food manufacturers must make an effort to let consumers know how their food is being processed within the walls of the factory and highlight the benefits vis-à-vis preparing foods in a domestic environment.

Correlating enzymatic browning inhibition and antioxidant ability of Maillard reaction products derived from different amino acids

BACKGROUND

Up to now, only limited research on enzymatic browning inhibition capacity (BIC) of Maillard reaction products (MRPs) has been reported and there are still no overall and systematic researches on MRPs derived from different amino acids. In the present study, BIC and antioxidant capacity, including 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and Fe²⁺ reducing power activity, of the MRPs derived from 12 different amino acids and three reducing sugars were investigated.

RESULTS

The MRPs of cysteine (Cys), cystine, arginine (Arg) and histidine (His) showed higher BIC compared to other amino acids. Lysine (Lys)-MRPs showed the highest absorbance value at 420 nm (A₄₂₀ ) but very limited BIC, whereas Cys-MRPs, showed the highest BIC and the lowest A₄₂₀ . The A₄₂₀ can roughly reflect the trend of BIC of MRPs from different amino acids, except Cys and Lys. MRPs from tyrosine (Tyr) showed the most potent antioxidant capacity but very limited BIC, whereas Cys-MRPs showed both higher antioxidant capacity and BIC compared to other amino acids. Partial least squares regression analysis showed positive and significant correlation between BIC and Fe²⁺ reducing power of MRPs from 12 amino acids with glucose or fructose, except Lys, Cys and Tyr. The suitable pH for generating efficient browning inhibition compounds varies depending on different amino acids: acidic pH was favorable for Cys, whereas neutral and alkaline pH were suitable for His and Arg, respectively. Increasing both heating temperature and time over a certain range could improve the BIC of MRPs of Cys, His and Arg, whereas any further increase deteriorates their browning inhibition efficiencies.

CONCLUSION

The types of amino acid, initial pH, temperature and time of the Maillard reaction were found to greatly influence the BIC and antioxidant capacity of the resulting MRPs. There is no clear relationship between BIC and the antioxidant capacity of MRPs when reactant type and processing parameters of the Maillard reaction are considered as variables. © 2017 Society of Chemical Industry.

Supplementation of fermented Maillard-reactive whey protein enhances immunity by increasing NK cell activity

Objective: The objective of this study was to investigate the impact of supplementation with fermented Maillard-reactive whey protein (F-MRP) on natural killer (NK) cell activity, circulating cytokines, and serum protein levels.

Antioxidant Properties of Heterocyclic Intermediates of the Maillard Reaction and Structurally Related Compounds

It is well established that a wide range of reductones is formed in the course of the Maillard reaction and that these substances contribute to the oxidative stability of food. The aim of this study was to analyze 12 important heterocyclic intermediates with and without reductone structure as well as structurally related substances under equal conditions to compare their antioxidant properties in detail. For this purpose, five methods were selected including photometrical methods such as the trolox equivalent antioxidant capacity assay and an electron paramagnetic resonance spectroscopic method. Reductones with furan-3-one structure and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one were reducing in all assays, whereas isomaltol and maltol did not react in assays based on the reduction of metal ions because of their complexing abilities. The introduction of protecting groups to the free hydroxyl functions of selected reductones could nearly eliminate their reducing abilities. In addition, the oxidation products of the different reductive heterocycles were compared after treatment with iodine. Mainly short-chained organic acids such as lactic, glycolic, and glyceric acid are formed as result of the degradation, which indicates 1,3-dicarbonyl cleavage reactions of corresponding tricarbonyl compounds as intermediates of the oxidation.

Characterization and functional properties of mango peel pectin extracted by ultrasound assisted citric acid

Pectin was extracted from 'Tainong No. 1' mango peels, using a chelating agent-citric acid as extraction medium by ultrasound-assisted extraction (UAE) and conventional extraction (CE) at temperatures of 20 and 80°C. Chemical structures, rheological and emulsifying properties of mango peel pectins (MPPs) were comparatively studied with laboratory grade citrus pectin (CP). All MPPs exhibited higher protein content (4.74%-5.94%), degree of methoxylation (85.43-88.38%), average molecular weight (Mw, 378.4-2858kDa) than the CP, but lower galacuronic acid content (GalA, 52.21-53.35%). CE or UAE at 80°C resulted in significantly higher pectin yield than those at 20°C, while the extraction time for UAE-80°C (15min) was significantly shorter compared to CE-80°C (2h) with comparable pectin yield. Moreover, MPPs extracted at 80°C were observed with higher GalA and protein content, higher Mw, resulting in higher viscosity, better emulsifying capacity and stability, as compared to those extracted at 20°C and the CP. Therefore, these results suggested that MPPs from 'Tainong No. 1' may become a highly promising pectin with good thickening and emulsifying properties, using ultrasound-assisted citric acid as an efficient and eco-friendly extraction method.

Identification and Antioxidant Properties of Phenolic Compounds during Production of Bread from Purple Wheat Grains

Phenolic profiles and antioxidant properties of purple wheat varieties were investigated to document the effects of bread-making. Bread crust and crumb along with samples collected after mixing, 30 min fermenting, 65 min fermenting, and baking were examined. Free phenolic content (105.4 to 113.2 mg FAE/100 g) significantly (p < 0.05) increased during mixing, fermenting, and baking (65% to 68%). Bound phenolics slightly (p > 0.05) decreased after 30 min fermentation (7% to 9%) compared to the dough after mixing, but increased significantly (p < 0.05) during 65 min fermenting and baking (16% to 27%). Their antioxidant activities followed a similar trend as observed for total phenolic content. The bread crust demonstrated increased free (103% to 109%) but decreased bound (2% to 3%) phenolic content, whereas bread crumb exhibited a reversal of these results. Total anthocyanin content (TAC) significantly (p < 0.05) decreased by 21% after mixing; however, it gradually increased to 90% of the original levels after fermenting. Baking significantly (p < 0.05) decreased TAC by 55%, resulting in the lowest value for bread crust (0.8 to 4.4 mg cyn-3-glu equiv./100 g). p-Hydroxybenzoic, vanillic, p-coumaric, and ferulic acids were detected in free-phenolic extracts, while protocatechuic, caffeic syringic, and sinapic were additional acids in bound-phenolic extracts. Cyanidin-3-glucoside was the detectable anthocyanin in purple wheat. Bread-making significantly (p < 0.05) increased the phenolic content and antioxidant activities; however, it compromised the anthocyanin content of purple wheat bread.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation and fate: an example of the coordinate contribution of lipid oxidation and Maillard reaction to the production and elimination of processing-related food toxicants

Major chemical reactions dealing with carbonyl chemistry in foods (Maillard reaction and lipid oxidation) play a role in PhIP formation and fate, pointing to this and analogous heterocyclic aromatic amines as outcomes of this chemistry.

The colorants, antioxidants, and toxicants from nonenzymatic browning reactions and the impacts of dietary polyphenols on their thermal formation

Nonenzymatic browning reactions proceed with the starting reactants of sugar and/or protein during thermal processing and storage of food.

Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity

BACKGROUND

A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program.

RESULTS

The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm.

CONCLUSION

A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed.

Effects of certain polyphenols and extracts on furans and acrylamide formation in model system, and total furans during storage

Using a glucose-glycine and asparagine-fructose system as a Maillard reaction model, the effects of seven polyphenols and solid phase extracts of three plants on the formation of furans and acrylamide were investigated. The polyphenols and extracts were used in biscuit formulation and acrylamide formation was observed. They were used for the storage of the glycine-glucose model system at three different temperatures. The addition of some of the extracts and polyphenols significantly decreased furan formation to different extents. All phenolic compounds and plant extracts decreased in the range of 30.8-85% in the model system except for oleuropein, and all of them decreased in the range of 10.3-19.2% in biscuit. Total furan formation was inhibited by caffeic acid, punicalagin, epicatechin, ECE and PPE during storage. This study evaluated and found the inhibitory effect on the formation of furans and acrylamide in Maillard reactions by the use of some plant extracts and polyphenols.

Demonstration of antioxidant and anti-inflammatory bioactivities from sugar-amino acid maillard reaction products

Maillard reaction products (MRPs), both crude and fractionated, were assessed for antioxidant potential using cell-free, in vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, Fenton reaction induced deoxyribose degradation and oxygen radical absorbance capacity-fluorescein (ORACFL) chemical assays. All MRPs displayed various affinities to scavenge free radicals generated in different reaction media and using different reactive oxygen species (ROS) substrates. High molecular weight MRPs consistently showed the greatest (P < 0.05) antioxidant potential in chemical assays. Repeating these tests in Caco-2 cells with both reactive oxygen and nitrogen (RNS) intracellular assays revealed that the low molecular weight components (LMW) were most effective at inhibiting oxidation and inflammation. In particular, a glucose-lysine (Glu-Lys) mixture heated for 60 min had marked intracellular antioxidant activity and nitric oxide (NO) and interleukin-8 (IL-8) inhibitory activities compared to other MRPs (P < 0.05). Further studies employing ultrafiltration, ethyl acetate extraction, and semipreparative high-performance liquid chromatography (HPLC) produced a bioactive fraction, termed F3, from heated Glu-Lys MRP. F3 inhibited NO, inducible nitric oxide synthetase (iNOS), and IL-8 in interferon γ (IFN-γ)- and phorbol ester (PMA)-induced Caco-2 cells. F3 modified several gene expressions involved in the NF-κB signaling pathway. Two components, namely, 5-hydroxymethyl-2-furfural (HMF) and 5-hydroxymethyl-2-furoic acid (HMFA), were identified in the F3 fraction, with an unidentified third component comprising a major portion of the bioactivity. The results show that MRP components have bioactive potential, especially in regard to suppressing oxidative stress and inflammation in IFN-γ- and PMA-induced Caco-2 cells.

Antioxidants in food: mere myth or magic medicine?

The powerful action of antioxidants in preventing premature lipid oxidation in food suggests that the same compounds, when consumed with the daily diet, could unfold antioxidative/anti-aging effects in the human body. Therefore, it has been hypothesized that antioxidants are helpful in preventing various diseases. More detailed chemical and physiological examination of antioxidants shows, however, that the extrapolation of in vitro data to in vivo behavior may be misleading. Indeed, such a procedure fails to take into account the mismatch between most in vitro models (e.g., cell cultures) and in vivo systems. For example, the physiological relevance of pro-oxidative and other physiological activities of antioxidants have been largely underestimated. Actually, contrary to the antioxidant hypothesis, clinical trials testing the health benefits of dietary antioxidants have reported rather mixed or negative results. Many clinical studies have not taken into account the nutrikinetic and nutridynamic nature of antioxidants. Further, oxidative stress is not only an inevitable event in a healthy human cell, but responsible for the functioning of vital metabolic processes, such as insulin signaling and erythropoietin production. In the light of recent physiological studies it appears more advisable to maintain the delicate redox balance of the cell than to interfere with the antioxidant homeostasis by a non-physiological, excessive exogenous supply of antioxidants in healthy humans.

Novel insights into the maillard catalyzed degradation of maltose

Numerous investigations concerning Maillard degradation of carbohydrates clearly depict the important impact of α-dicarbonyl compounds on changes occurring during preparation of food or physiological processes in vivo. To study the formation of these reactive intermediates during degradation of maltose in the presence of lysine, α-dicarbonyl compounds were isolated, identified and quantified after reaction with o-phenylenediamine to form their stable quinoxaline derivatives. Maltosone and 1,4-dideoxyglucosone were synthesized and incubated independently with lysine to investigate follow-up products and to gain further insights into the complex degradation mechanisms. Glyoxylic acid as a dicarbonyl structure and 5,6-dihydroxy-2,3-dioxohexanal as a 1,2,3-tricarbonyl compound were established as novel Maillard degradation products of maltose. Conducted experiments unequivocally demonstrated that inter- and intramolecular redox reactions are of major importance during degradation of disaccharides. 1,4-Dideoxyglucosone, 1-lysino-1,4-dideoxyglucosone, 5,6-dihydroxy-2,3-dioxohexanal, 3,4-dideoxypentosone and glyoxylic acid were found to be the central intermediates involved in the redox chemistry. With the present study we deliver a comprehensive overview on the mechanisms behind α-dicarbonyl compounds evolving from Maillard degradation of maltose.

Formation of acrylamide at temperatures lower than 100°C: the case of prunes and a model study

Acrylamide concentrations in prune products – baby strained prunes (range = 75–265 μg kg⁻⁻¹), baby apple/prune juice (33–61 μg kg⁻⁻¹), prune juice (186–916 μg kg⁻⁻¹) and prunes (58–332 μg kg⁻⁻¹) – on the Canadian market were determined. The formation of acrylamide in a simulated plum juice was also investigated under ‘drying conditions’ in an open vessel at temperatures <100°C for 24 h and under ‘wet conditions’ in a closed vessel at a temperature of 120°C for 1 h. Acrylamide was produced in a simulated plum juice under ‘drying conditions’ in amounts comparable with those found in prunes and prune juices. Acrylamide was not produced in simulated plum juice under ‘wet conditions’ in a closed vessel at temperature of 120°C for 1 h, but under the same condition an authentic prune juice doubled its acrylamide concentration. Formation of acrylamide in prune products was attributed to the presence of asparagine and sugars in the starting materials.

Formation of carcinogenic 4(5)-methylimidazole in Maillard reaction systems

4(5)-Methylimidazole has received the attention of federal and state regulatory agencies because of its carcinogenicity and common presence in foods and beverages. In the present study, the formation of 4(5)-methylimidazole in Maillard reaction model systems consisting of D-glucose/NH(3), L-rhamnose/NH(3), methylglyoxal/NH(3), and methylglyoxal/formaldehyde/NH(3) was investigated. 4(5)-Methylimidazole was formed at levels ranging from 0.49 to 0.71 mg/mL in the d-glucose/NH(3) model system. The formation of 4(5)-methylimidazole was slightly higher in the L-rhamnose/NH(3) system (0.91 mg/mL) than in the d-glucose/NH(3) system (0.71 mg/mL) under the conditions used in the present study. A methylglyoxal/NH(3) system produced significantly higher levels of 4(5)-methylimidazole (5.70 mg/mL), suggesting that methylglyoxal is an important precursor of 4(5)-methylimidazole. Ammonolysis of methylglyoxal, which is one of the glucose degradation products, was proposed to form formamide, which subsequently reacted with 2-aminopropanal (α-aminocarbonyl intermediate) formed from methylglyoxal to give 4- or 5-methylimidazole. The levels of 4(5)-methylimidazole found in commercial cola soft drinks range from 0.30 μg/mL (brand 3) to 0.36 μg/mL (brands 1 and 5).

Antioxidant capacity of potato chips and snapshot trends in acrylamide content in potato chips and cereals on the Canadian market

The concentration of acrylamide was measured in selected varieties of five brands of potato chips and breakfast cereals over a 5-year period. Most of the products were purchased in one locality in Canada. Samples were analysed by an isotope dilution ((13)C(3)) acrylamide method. They were extracted with water, partitioned with dichloromethane, filtered through a 5 kDa centrifuge filter, cleaned-up on HLB Oasis polymeric and Accucat mixed mode anion and cation exchange SPE columns, and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The acrylamide concentration in potato chips varied from 106 to 4630 ng g(-1), while values in cereals varied from 50 to 347 ng g(-1). Wide variations were observed between brands, within brands over time, and between lots of the same brand. A subset of potato chip samples was analysed for in vitro antioxidant activity. No relationship was found between antioxidative capacity of potato chips and their acrylamide content.

Biscuit melanoidins of different molecular masses protect human HepG2 cells against oxidative stress

Soluble melanoidins from biscuits were enzymatically solubilized and isolated by sequential ultrafiltration and separated by molecular mass in three different fractions, below 3 kDa, between 3 and 10 kDa, and over 10 kDa; the latter was subsequently digested by simulating gastric plus pancreatic digestive conditions. The four fractions were investigated for their protective effect against an oxidative challenge in HepG2 cells. Pretreatment of cells for 20 h with 0.5-10 microg/mL of any of the four fractions prevented the increased cell damage evoked by the challenge but, except for the intermediate size fraction, did not suppress the increased reactive oxygen species. Antioxidant defenses were rapidly restored after the challenge, and the increase of the oxidative stress biomarker malondialdehyde was prevented by the pretreatment with all but the undigested high molecular mass fraction. The results show that treatment of HepG2 cells with concentrations of biscuit melanoidins within the expected physiological range confers on the cells a significant protection against an oxidative challenge.