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Abstract
This review summarizes the life and work of Louis‐Camille Maillard, the most worldwide renowned French biochemist of the 20th century. It focuses on the main events in Maillard's life and the reaction sugar–amino acids in his work, and offers an overview of the Maillard reaction in vitro and in vivo.
... The differential operation is performed on eqn (1) to obtain the reaction rate (r), as shown in eqn (2). At the same time, the reaction rate (r) is also related to the concentrations of the radical and the antioxidant, in which the coefficient is the rate constant (k). ...
It is well known that 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) is usually formed in the Maillard reaction and it contributes to the antioxidant properties of Maillard reaction intermediates. A series of hydroxyl group protected DDMP derivatives were synthesized to further understand the source of antioxidant activity. Antioxidant abilities of the DDMP derivatives were evaluated by scavenging the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS˙+), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical, respectively. It was found that the introduction of protecting groups to the free hydroxyl groups of DDMP decreases their reducing abilities. In particular, the hydroxyl group at the olefin position exhibited a remarkable impact on the antioxidant activity of DDMP, indicating that the unstable enol structure in the DDMP moiety is the key factor for its antioxidant activity.
... Presumptive identification can often be made by comparing the Kovats retention index value with a value previously published in literature references. Identification of the compounds was done by comparison: I: spectrum presented in NIST17 (NIST/EPA/NIH Mass Spectral Library); II: calculated retention index values with database NIST17; III: retention times of unknown compounds with available standards (1,3,5,8,11,14,15,16,18,20,23,30,32,39,40,43,44,45,47,48). ...
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.
... In addition to caramelization, sugars can impact flavor and color via the Maillard reaction [7]. The Maillard reaction was named after French chemist Louis-Camille Maillard, who, in 1912, originally observed and described the reaction between amino acids and reducing sugars [63]. It is generally recognized the Maillard reaction plays a predominant role in flavor development during the cooking of food. ...
Patients who are malnourished or at-risk for malnutrition often benefit from the consumption of oral nutritional supplements (ONS). ONS supply a range of micro- and macro-nutrients, and they can be used to supplement a diet or provide total nutrition. Since ONS are specially formulated products, all ONS ingredients—including carbohydrates—are added ingredients. This may seem to be at odds with the growing public health discourse on the need to reduce “added sugars” in the diet. However, carbohydrate is an essential nutrient for human health and is a critical ingredient in ONS. Helping to educate patients on the value of “added sugars” in ONS may be useful to improve compliance with nutritional recommendations when ONS are indicated. This perspective paper reviews the important roles of “added sugars” in ONS, in terms of flavor, function, and product formulation.
... For aroma compounds development, the most well-known reaction involving saccharides is when they react with compound possessing a free amino group (Maillard 1912). This reaction has been named after the French chemist Louis Maillard, who first described it in 1910, and is called Maillard reaction (Billaud and Adrian 2003). For as long as food has been cooked, MR has been applied to produce food, for example, fried meat, coffee, and bakery products, which possess the color and flavor FIGure 5.4 Formation of 2-hydroxy-3-methyl-2-cyclopentenone and 2-hydroxy-3,4dimethyl-2-cyclopentenone. ...
Saccharides are common components of foods as natural components and added ingredients. Together with lipids and proteins, they represent one of the basic nutrients serving as the most important source of energy in human diet. Because of their wide range of chemical and physical properties, saccharides have additionally many valuable functions in foods such as sweetening, gelatinization, thickening, or stabilization properties, and they can also act as precursors for aroma and coloring substances. Saccharides are also called carbohydrates, which suggests that they are all hydrates of carbon, namely, Cx(H2O)y. Among the most important types of carbohydrates in foods are the sugars, dextrins, starches, celluloses, hemicelluloses, pectins, and certain gums. By now, many other components such as deoxysugars, amino sugars, and sugar carboxylic acids have been included in this class of compounds. Basically, saccharides are divided into monosaccharides, oligosaccharides, and polysaccharides. For the development of food flavor, mostly monosaccharides are involved in the course of caramelization and Maillard reaction (MR). In this chapter, universal mechanisms and pathways in aroma compounds formation of process flavors from saccharides precursors will be discussed.
The Maillard reaction, named after the French chemist Louis-Camille Maillard who discovered it in 1912, is a non-enzymatic reaction that takes place between an available amino group and a carbonyl-containing moiety (Maillard in Compt Rend Acad Sci 154:66–68, 1912 [1]; Maillard in Compt Rend Soc Biol 72:599–601, 1912 [2]).
Sweeteners are the primary ingredients in the manufacture of confections. Chemically, the primary sweeteners in confections are carbohydrates, which consist of a group of widely varied chemical substances present in both plants and animals. For example, in dry corn, approximately 55% of the solids are carbohydrates. The word “carbohydrates” itself means hydrated carbon. Thus, carbohydrate chemistry mostly deals with chains of carbon atoms hydrated with water, with a general formula of Cx(H2O)y.
Caramel, fudge and toffee are distinguished from other sugar-based confections by the addition of milk or its components. The presence of milk ingredients during the cooking process generates unique colors, flavors and aromas associated with caramel, fudge and toffee.
Die 1912 erstmals von dem französischen Biochemiker Louis-Camille Maillard beschriebene Reaktion reduzierender Kohlenhydrate mit Aminokomponenten ist verantwortlich für den Geruch, den Geschmack und das Aussehen thermisch verarbeiteter Lebensmittel. Die Erkenntnis, dass entsprechende nicht-enzymatische Umsetzungen auch im Organismus auftreten, führte zur intensiven Erforschung der pathophysiologischen Bedeutung der Maillard-Reaktion bei Diabetes und Alterungsprozessen. Alimentäre Maillard-Produkte werden einerseits als “Glycotoxine” und damit als Ernährungsrisiko, andererseits jedoch auch vermehrt im Hinblick auf positive Wirkungen im menschlichen Körper diskutiert. In unserem Aufsatz geben wir einen Überblick zu den wichtigsten Erkenntnissen der Maillard-Forschung seit ihrer Erstbeschreibung und zeigen, dass die komplexe Reaktion auch nach über hundert Jahren nichts an interdisziplinärer Aktualität verloren hat.
The reaction of reducing carbohydrates with amino compounds described in 1912 by Louis-Camille Maillard is responsible for the aroma, taste, and appearance of thermally processed food. The discovery that non-enzymatic conversions also occur in organisms led to intensive investigation of the pathophysiological significance of the Maillard reaction in diabetes and ageing processes. Dietary Maillard products are discussed as "glycotoxins" and thus as a nutritional risk, but also increasingly with regard to positive effects in the human body. In this Review we give an overview of the most important discoveries in Maillard research since it was first described and show that the complex reaction, even after over one hundred years, has lost none of its interdisciplinary actuality.
The Maillard reaction of amino acids and reducing sugars is important for food flavor formation and for the biological ageing of living organisms. The redox nature of the reaction is examined by measurement of open-circuit galvanic cell potentials and by electrolytic methods including polarography and amperometry. Electrochemical detectors (ECD) designed on the basis of voltammetric principles are employed as useful tools for the detection and quantification of Maillard intermediates and final products. Galvanic potentials serve as useful indicators for highly reactive compounds like reductones while more stable intermediates such as Amadori compounds and pyranones are more readily analyzed by ECD/HPLC techniques. Electrochemical methods provide valuable non-invasive probes to follow the course of the Maillard reaction and for investigating its mechanism.Some sort of summary or recommendations here would be helpful.
INTRODUCTION MAILLARD CHEMISTRY CONTROLLING FACTORS SPECIFIC MAILLARD REACTION PRODUCTS INTERACTIONS OF MAILLARD REACTION AND LIPIDS
Nonenzymatic glycosylation of albumin in vivo occurs at multiple sites. Glucose gets attached to Lys-199, Lys-281, Lys-439, and Lys-525 as well as to some other lysine residues. The principal glycosylated site is Lys-525. Approximately 33% of the overall glycosylation occurs at this site. This site specificity is remarkable and is postulated to be a consequence of local catalysis of the nonenzymatic glycosylation reaction. It appears that positively charged amino groups in the protein catalyze the Amadori rearrangement at specific sites. The principal glycosylated site, Lys-525, lies in a Lys-Lys sequence; other glycosylated sites lie in a Lys-Lys, Lys-His, and Lys-His-Lys sequence or are near disulfide bridges, which are likely to place amino groups of more remote parts of the protein closer to these sites. The occurrence of nonenzymatic glycosylation at most of the identified sites in albumin from diabetic patients is explained by the concept of local acid-base catalysis of the Amadori rearrangement.
Hemoglobin AIc is a minor component of normal adult erythrocytes whose concentration is elevated approximately 2-fold in patients with diabetes mellitus. Previous work suggested that the unique structural feature of hemoglobin AIc is the presence of a low molecular weight sugar moiety at the NH2-terminal valine of the beta chain. In this study the structure of the carbohydrate moiety and the nature of its linkage of the beta chain were investigated. Enzymatic digestion of borohydride-reduced betaAIc chains followed by ion exchange chromatography led to the isolation of two distinct NH2-terminal glycovalylhistidines. Comparison of these glycodipeptides with synthetic glycovalylhistidines by thin layer chromatography, gas-liquid chromatography, and proton magnetic resonance spectroscopy gave direct evidence that the naturally derived materials correspond to glucitol and mannitol valylhistidines. Model reactions showed that glucose and mannose react with valine under mild conditions to form an adduct which upon sodium borohydride reduction yields in both cases glucitol and mannitol valines. This suggests a common intermediate, 1-deoxy-1-(N-valyl)fructose, for both reactions. From these studies we conclude that hemoglobin AIc has, as the NH2 terminus of the beta chain, 1-deoxy-1-(N-valyl)fructose. The possible biosynthetic pathways of hemoglobin AIc are discussed.
The formation of sugar-cataracts has been hypothesized to involve the nonenzymatic glycosylation, sulfhydryl oxidation, and aggregation of lens proteins. Cataractous lenses of diabetic and galactosemic rats were analyzed for glycosylated lysine residues in crystallins. A five- and a ten-fold increase in glycosylated lysine residues was measured in galactose and diabetic cataracts, respectively. The modification was predominant in the insoluble fraction of the lens homogenate. The proteins were further examined for the presence of disulfide bonds and high molecular weight aggregates. After careful disruption of the lens in a nitrogen environment, a cloudy solution was obtained from cataractous lenses whereas a clear solution was obtained from normal lenses. The absorbance at 550 nm of the solution of both the galactosemic and the diabetic cataracts could be decreased by approximately 50% with the addition of dithioerythritol (50 mM). The presence of high molecular weight aggregates was ascertained by sucrose gradient centrifugation and gel filtration chromatography. The proteins were heterogenous in size and showed a mol wt range of 36 to greater than 176 million daltons. Treatment with dithioerythritol induced a marked decrease in the amount of high molecular weight proteins. These data suggest that sugar cataracts of experimental animals have, in common with human cataracts, the presence of high molecular weight aggregates which are in part linked by disulfide bonds.
Nonenzymatic glycosylation of albumin in vivo occurs at multiple sites. Glucose gets attached to Lys-199, Lys-281, Lys-439, and Lys-525 as well as to some other lysine residues. The principal glycosylated site is Lys-525. Approximately 33% of the overall glycosylation occurs at this site. This site specificity is remarkable and is postulated to be a consequence of local catalysis of the nonenzymatic glycosylation reaction. It appears that positively charged amino groups in the protein catalyze the Amadori rearrangement at specific sites. The principal glycosylated site, Lys-525, lies in a Lys-Lys sequence; other glycosylated sites lie in a Lys-Lys, Lys-His, and Lys-His-Lys sequence or are near disulfide bridges, which are likely to place amino groups of more remote parts of the protein closer to these sites. The occurrence of nonenzymatic glycosylation at most of the identified sites in albumin from diabetic patients is explained by the concept of local acid-base catalysis of the Amadori rearrangement.
The formation of sugar-cataracts has been hypothesized to involve the nonenzymatic glycosylation, sulfhydryl oxidation, and aggregation of lens proteins. Cataractous lenses of diabetic and galactosemic rats were analyzed for glycosylated lysine residues in crystallins. A five- and a ten-fold increase in glycosylated lysine residues was measured in galactose and diabetic cataracts, respectively. The modification was predominant in the insoluble fraction of the lens homogenate. The proteins were further examined for the presence of disulfide bonds and high molecular weight aggregates. After careful disruption of the lens in a nitrogen environment, a cloudy solution was obtained from cataractous lenses whereas a clear solution was obtained from normal lenses. The absorbance at 550 nm of the solution of both the galactosemic and the diabetic cataracts could be decreased by approximately 50% with the addition of dithioerythritol (50 mM). The presence of high molecular weight aggregates was ascertained by sucrose gradient centrifugation and gel filtration chromatography. The proteins were heterogenous in size and showed a mol wt range of 36 to greater than 176 million daltons. Treatment with dithioerythritol induced a marked decrease in the amount of high molecular weight proteins. These data suggest that sugar cataracts of experimental animals have, in common with human cataracts, the presence of high molecular weight aggregates which are in part linked by disulfide bonds.
A convenient one-step synthesis of 14C-labelled 2,5-dimethyl-4-hydroxy-3(2H)-furanone (furaneol) was accomplished by a piperidine acetate catalyzed Maillard-type reaction of commercially available fucose L-[1-14C]. This important aroma compound found in strawberry fruits, obtained in ≥ 90 % radiochemical purity, should prove useful in in-vivo metabolism studies. © 1997 John Wiley & Sons, Ltd.
The chemical structure of a novel intense popcorn-like odorant isolated from the reaction of cysteine and ribose was studied by one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry, and the structure elucidation was confirmed by synthetic experiments. Thus, the odorant was identified as 5-acetyl-2,3-dihydro-1,4-thiazine (ADT). A sensory study including 5-propionyl- (PDT) and 5-butanoyl-2,3-dihydro-1,4-thiazine (BDT) revealed that also PDT and BDT elicited roasty, popcorn-like odors. However, the odor threshold of the BDT was by a factor of 50 000 higher than those of ADT and PDT (0.06 and 0.1 ng/L of air, respectively).
Numerous sulfur-containing volatile compounds were released from an extruder when cysteine was added to wheat flour before extrusion. The volatiles released were collected in a specially designed cryogenic apparatus at the die of the twin-screw extruder. Five concentrations of cysteine were used (0 to 10 g/kg). Among the identified sulfur-containing compounds, meat-like flavor compounds, such as 2,4-dimethyl-3-thiazoline, 2-methylthiazolidine, 3,5-dimethyl-1,2,4-trithiolane, and 2,4,6-trimethyl-perhydro-1,3,5-dithiazine, were collected in the highest amounts. Several nonsulfur containing compounds such as methylpyrazine, 2,6-dimethylpyrazine, and 2-acetyl furan were also found in the condensate. The total amount of volatiles collected increased when more cysteine was added to the flour, but only a small fraction of added cysteine formed flavor volatiles in both the condensate and extrudate.
The Maillard reaction is one of the most commonly studied reactions in food chemistry as it is responsible for both flavor generation and the surface browning of heated foods. Conventional research on the thermal generation of aromas via the Maillard reaction pathways has focused mainly on the reaction between free amino acids and reducing sugars in model systems. These studies, although extremely important, do not investigate the role of peptide-bound amino acids as possible Maillard reactants. Some recent work on this subject has indicated that protein structure and the peptide sequence may dictate the profile of resulting aroma volatiles generated and that unique peptide-specific volatiles can be formed.
Inhibition of proteases was examined in browned foods including soy pastes, soy sauces, fish sauce, sauces, teas, coffees, and others in association with melanoidin, a Maillard product, which had been found to be a potent inhibitor of trypsin. Most of the foods were effective in restraining trypsin activity based on hydrolysis of N-α-benzoyl- DL- arginine-p-nitroanilide, while being ineffective on chymotrypsin except for black tea and cola. Especially, teas were noted for their strung inhibitory effect on trypsin. The color intensity of the foods in terms of optical density at 400 nm appeared not to correlate with the extent of inhibition except for soy sauces.
The reactions that occur during the cooking, baking, and preservation of foods of all kinds are of great importance for the production of aroma, taste, and color. However, more recently it has been shown that these reactions may be accompanied by a reduction in nutritive value and the formation of toxic compounds. For these reasons, the very complex reactions between reducing sugars and the free amino groups of amino acids or proteins, known as non-enzymatic browning or the Maillard reaction, have again caught the interest of chemists. The Maillard reaction came to be seen in a new light as it was realized that it actually occurred in the human body. As a general rule, the longer the half-life of a protein, the larger the amount of its Maillard products found, i.e., important factors are the ‘age’ or persistence of the protein in the body and the glucose concentration, particularly in diabetics. Many of the symptoms developed by diabetics resemble those of premature aging, which leads to the possibility that glucose, because of its reactivity towards proteins, is fundamentally involved in the normally slow progress of aging.
Ribonucleinsäure wurde trocken, in wä\riger Lösung und zusammen mit Glukose erhitzt. Die chemischen Veränderungen bestehen erstens in der Spaltung der N-glykosidischen Bindung, vorwiegend der Purinbasen, und zweitens im Abbau des MakromolekÜls durch Spaltung der Phosphoresterbindung.
Die akute Toxizität der Ribonucleinsäure ist sehr gering. Sie nimmt bei den erhitzten RNS-Präparaten zu. Die täglich durch die Nahrung aufgenommene Ribonucleinsäuremenge liegt jedoch weit unter der kritischen Grenze. Vom ernährungsphysiologischen Standpunkt aus können sowohl die Ribonucleinsäure als auch die erhitzten Ribonucleinsäuren als unbedenklich angesehen werden.
Application of aroma extract dilution analysis on two different model mixtures of proline and glucose, reacted under aqueous or dry-heating conditions, revealed 2-propionyl-1-pyrroline (PP) and 2-propionyltetrahydropyridine (PTHP; occurring in two tautomers), besides 2-acetyl-1-pyrroline and 2-acetyltetrahydropyridine, as important roast-smelling odorants in both mixtures. A comparison of the isotope distribution in PP and PTHP formed from either 13C6-labeled or unlabeled glucose suggested a formation pathway for both odorants from the same intermediate, 1-pyrroline, when reacted with either 2-oxobutanal (yielding PP) or 1-hydroxy-2-butanone (yielding PTHP). 2-Oxobutanal, a possible precursor of 1-hydroxy-2-butanone, was shown to be formed in high yields (29 mol %) by reacting acetaldehyde and glycolaldehyde, two well-known degradation products of carbohydrates. Keywords: Maillard reaction; labeling experiments; 2-acetyl-1-pyrroline; 2-acetyltetrahydropyridine; 2-propionyl-1,4,5,6-tetrahydropyridine; 2-propionyl-3,4,5,6-tetrahydropyridine; 2-propionyl-1-pyrroline
Toasting wood to be used in barrels for aging wine and brandy produces a great number of volatile and odiferous compounds. Some of these have a “toasty caramel” aroma. Analysis by high-performance gas chromatography of toasted oak extracts, combined with olfactory detection, enabled various chromatographic peaks with these specific aromas to be isolated. These same odors were simultaneously studied by heating glucose both with and without proline. Aromatic compounds of interest were identified thanks to a combination of gas chromatography and both mass and infrared spectrometry. In addition to already-known substances such as 2-hydroxy-3-methyl-2-cyclopenten-1-one (cyclotene) (1) and 3-hydroxy-2-methyl-4H-pyran-4-one (maltol) (2), we identified, for the first time, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) (3), 4-hydroxy-2,5-dimethyl-3(2H)-furan-3-one (furaneol) (4), and 2,3-dihydro-5-hydroxy-6-methyl-4H-pyran-4-one (dihydromaltol) (5) as compounds which actively contribute to the “toasty caramel” aroma of heated oak. Their role in the aroma of wines and spirits is thus well worth studying. These molecules were absent from the glucose pyrolysis but were relatively plentiful after heating in the presence of proline. Therefore, Maillard reactions were seen to be the cause of these substances in the heated oak wood. Keywords: Oak; thermal degradation; volatile compounds; “toasty” aroma; Maillard reactions
Enzymatic and nonenzymatic browning reactions of amino acids and proteins with carbohydrates, oxidized lipids, and oxidized phenols cause deterioration of food during storage and processing. The loss in nutritional quality and potentially in safety is attributed to destruction of essential amino acids, decrease in digestibility, inhibition of proteolytic and glycolytic enzymes, interaction with metal ions, and formation of antinutritional and toxic compounds. Studies in this area include influence of damage to essential amino acids on nutrition and food safety, nutritional damage as a function of processing conditions, and simultaneous formation of deleterious and beneficial compounds. These compounds include kidney-damaging Maillard reaction products, mutagens, carcinogens, antimutagens, antioxidants, antibiotics, and antiallergens. This overview covers the formation, nutrition, and safety of glycated proteins, characterized browning products, and heterocyclic amines. Possible approaches to inhibiting browning reactions and preventing adverse effects of browning during food processing and food consumption, including protection against adverse effects of heterocyclic amines by N-acetylcysteine, caffeine, chlorophyll, conjugated linoleic acid, lignin, and tea extracts, are also described. This research subject covers a complex relationship of the chemistry, biology, and pathology of browning products and the impact on human nutrition and health. Future study should differentiate antinutritional and toxicological relationships, define individual and combined potencies of browning products, and develop means to prevent the formation and to minimize the adverse manifestations of the most antinutritional and toxic compounds. Such studies should lead to better and safer foods and improved human health. Keywords: Browning prevention; food browning; food safety; glycated proteins; glycosylation; heterocyclic amines; human health; Maillard products; nutrition
Steam-volatile components from cocoa beans were examined on a support-coated capillary gas Chromatographic column coupled to a mass spectrometer. Of the identified compounds, the following contribute to cocoa aroma : acetaldehyde, isobutyralde hyde, isovaleraldehyde, benzaldehyde, phenylacetaldehyde, 5-methyl-2-phenyl-2-hexenal, 2-furaldehyde, methyl disulfide, 11 alkyl-substituted pyrazines, acetic acid, and isopentyl acetate. Possible precursors of the pyrazine compounds are discussed.
Many different types of organic reactions lead to the production of brown pigments at moderate temperatures. In spite of many reviews of the subject, there has been no comprehensive organization of the reactions. In this review some relationships are shown to exist among the carbonyl-amino, the nonamino, and the oxidative types of browning. Recent findings have provided the basis for an integration of the several isolated partial theories of browning (Maillard, sugar fission, ascorbic acid, furaldehyde) heretofore proposed. The significance of the occurrence of the Amadori rearrangement in the Maillard reaction is stressed, and a mechanism for browning in sugar-amine systems based upon the rearrangement is outlined. Attention is directed to the little-studied but important role of dehydrogenated reductones in both enzymatic and nonenzymatic browning reactions. Investigations of browning reactions in model systems during the past 3 years are reviewed, with the pertinent older studies, and the results of most of these are shown to fit into the proposed scheme of reactions. A classified directory to the major part of 201 references on browning in nitrogenous model systems (1940 to March 1953) is included.
The effects of pure, synthetic compounds, similar to or identical with those formed in the Maillard reaction, on the activity of carboxypeptidase A (EC 3.4.12.2) and purified, intestinal brush border enzyme aminopeptidase N (EC 3.4.11.2) were studied. A number of furans and pyrroles inhibited carboxypeptidase A. The strongest inhibitors had a carboxylic acid as a substituent on the furan ring, and their effects were characterized as an induced substrate inhibition. A few competitive inhibitors of aminopeptidase N were found, the most effective being DL-2-formyl-5-(hydroxymethyl)pyrrole-1-norleucine. This compound also inhibited carboxypeptidase A. When fed to rats (3 mg in a 1-g portion), it reduced the plasma level of lysine coming from the diet.
The effect of a glucose-lysine reaction mixture on protein digestion in rats was studied by using 3H-labeled free lysine, 14C-or 3H-labeled protein-bound lysine and "S-labeled protein-bound cystine in the experimental diets. The low- molecular-weight part of the glucose-lysine reaction mixture (1.5% wt/wt in the diet) affected the utilization of dietary protein-derived amino acids, as revealed by the ratio and the levels of different labels in plasma after feeding. The browned crust from a heated minced-meat loaf was less well digested and had a lower biological value than the crumb in a nitrogen-balance study with rats. When the water-soluble fraction of the crust was removed, the biological value of the crust was restored to the value of the crumb but the digestibility remained low. The addition of the water-soluble fraction of the crust had only a slight effect on the digestibility of the crumb. It is concluded that compounds in the glucose-lysine reaction model affect the dietary protein utilization of rats but were not present or otherwise could not explain the reduced utilization of proteins in the crust of the heated meat product. J. Nutr. 114: 2228-2234, 1984.
Several volatile heterocyclic compounds formed in Maillard reactions were evaluated for antioxidative activity. Antioxidative activity was measured by the oxidation of heptanal to heptanoic acid or by malonaldehyde formation. Alkylthiophenes, 2-thiophenethiol, 2-methyl-3-furanthiol, and furfuryl mercaptan inhibited heptanal oxidation for up to 30 days. The degree of unsaturation in the heterocyclic ring, as well as the substituent type, had variable effects on the antioxidative capacity of these compounds. The tert-butyl hydroperoxide induced oxidation of tocopherol-stripped corn oil, as measured by malondialdehyde formation, was also inhibited in the presence of these heterocyclic compounds. Reactions of the above compounds with tert-butyl hydroperoxide and m-chloroperoxybenzoic acid resulted in the formation and identification of various oxidized products. The products of these reactions suggested that these heterocyclic Maillard reaction products had antioxidative activity.
The objective was to determine the bile acid binding capacity of Maillard reaction products (MRPs) and its effect on plasma cholesterol (chol) and gastrointestinal weight in rats. MRP was prepared by heating a mixture of 3 M a-D-glucose and 3 M L-lysine at pH 9.0 and washing with ethanol to reduce low molecular weight MRP. In vitro data indicated that high molecular weight MRP bound cholic and chenodeoxycholic acid. Purified diets were prepared with 5% cellulose (C), 2.5% MRP plus 2.5% cellulose (CM), or 5 % MRP (M) and fed to three groups of male Wistar rats (n = 10) for 4 weeks. Each diet contained 1% chol and 0.2% cholic acid to induce hypercholesterolemia. In the M group plasma chol was significantly higher than in the C group, but liver chol did not differ between the C and M groups. In the CM group liver chol was higher but plasma chol did not differ from that in the C group. Total small intestine and mucosa weights were significantly higher in the M than in the C or CM groups. The cecum in the M group was about 3-fold heavier than in the C or CM groups. Thus, MRPs do not lower chol levels; however, they do increase gastrointestinal weight.
The effect of glucose, fructose and sucrose aqueous solutions on polyphenol oxidase (PPO) and peroxidase (POD) activity was studied. Solutions with high concentrations of sugars showed a slight inhibiting effect on PPO while an activation was observed for POD. Glucose solutions, tested after sufficient heat treatments, showed an inhibiting action only on PPO activity. Maillard reaction products, obtained by heating a glucose/glycine solution, caused an unexpectedly strong inhibiting effect on both enzymes. The inhibition became more evident with increasing heating times of the glucose/glycine solution, reducing the activity of PPO and POD nearly to zero. Thus, the Maillard reaction products, already known for their antioxidant properties, were also shown to have a strong inhibiting effect on enzymatic browning.
A complex chemical transformation known as the Maillard reaction may occur in foods containing reducing sugars and compounds with free amino groups. This reaction is accelerated by heating but occurs also at room temperature. Some food flavors, colors and texture characteristics depend on this reaction, but reduced nutritive values of proteins are also reported. To evaluate the contribution of digestive enzymes inhibition to this effect, activities of some proteases (pepsin, trypsin and chymotrypsin) were tested in the presence of glucose-glycine solutions heated at 90C for different times.
Pepsin was partially inhibited by glycine itself but Maillard reaction products (MRP) did not produce additional effect. MRP showed a limited inhibition on trypsin and chymotrypsin. Unfractionated MRP solution showed an inhibiting effect on trypsin of the same order as already reported by Oeste (1989) for the low molecular weight (LMW) fraction of glucose-lysine MRP. High molecular weight (HMW) MRP presented an additional inhibiting effect, beside that reported for LMW on chymotrypsin. This however only occurred in particular conditions.
Three short-term bioassays were employed to assess the clastogenic and mutagenic activities of Maillard reaction sugar-amino acid solutions at initial pH values of 7 and 10. All of the Maillard reaction solutions with no S9 activation induced significant increases in chromosome aberrations in Chinese hamster ovary (CHO) cells. Mitotic recombination and mutation occurred in Saccharomyces cerevisiae strain D5 cells when exposed to all Maillard reaction solutions. When Salmonella typhimurium TA100 cells were treated with Maillard reaction compounds, induction of revertants to histidine prototrophy occurred. Mutagen concentration in the browning reaction solution was dependent on initial pH.
Caramelisation products (CP) were prepared by heating a sucrose solution (1.47 M) at 200 °C under various conditions to study the inhibitory activity of CP on enzymic browning. Inhibition by fractionated CP was measured by enzymic kinetic analysis of polyphenol oxidase (PPO) and o-dihydroxyphenols, such as 4-methylcatechol (4-MC), catechol, caffeic acid and DL-3,4-dihydroxyphenylalanine (DL-DOPA). Colour intensity of CP produced at pH 4 was higher than that produced at pH 6 and pH 8, and increased with heating time. The reducing power of CP and their inhibitory effect on enzymic browning increased with prolonged heating and with increased amounts of CP. CP heated at pH 4 and pH 6 for 90 min gave a relative inhibitory activity on enzymic browning of 85.8% and 72.2%, respectively. One of two CP fractions obtained by Biogel P6 column chromatography had an inhibitory effect on enzymic browning, with the fraction having a molecular weight of 1000–3000 showing the highest activity. Based on the double reciprocal plot of the PPO and 4-MC system, the active fraction of CP appeared to be a competitive inhibitor and was most effective on inhibition of catechol browning, followed by caffeic acid and DL-DOPA.
In this article current knowledge about the Maillard reactionin vivo is described first, especially the glycosylation reactions of various tissues and the identification of different final products and intermediates of Maillard reaction.
The influence of MRP on digestion is of significant importance. These products are absorbed in different ways and are excreted in various amounts. Hence, the organism is variably influenced by MRP.
The influence of defined MRP, of glycosylated proteins and of melanoidines on glycosidases and proteases is described. The effects produced depend on the enzyme and on the used MRP. Reactive α-dicarbonyl compounds play an important role in the organism. Further possible reactions of these compounds caused by reductases are discussed.
The protein structure of enzymes is changed by Maillard reaction. Thereby the enzyme activity is influenced by covalent modifications of different amino acids and by inter- and intramolecular crosslinking.
Finally, the use of enzymes and monoclonale antibodies for detection of MRP is discussed.
To demonstrate whether caramelization products (CP) and Maillard reaction products (MRP) could inhibit enzymatic browning and/or inactivate apple polyphenoloxidase (PPO), l-cysteine, d-glucose, d-fructose aqueous solutions and equimolar mixtures (1 M) of hexose/cysteine were each tested on purified enzyme activity, using both spectrophotometric and polarographic methods. Inhibition was evaluated as a function of temperature (80–110 °C), time (0–48 h) of heating and concentration of reactants. High (1–2.7 M) concentrations of hexoses were needed to develop a slight inhibiting effect on PPO activity. Heating at 90 °C for extended time periods, increased their inhibitory effect. Unheated or heated cysteine solutions exhibited an inhibitory effect in terms of browning intensity, without noticeably affecting PPO activity. Conversely, MRP showed a very strong inhibitory potency. Inhibition efficiency increased with heating time and temperature. The extent of inhibitory effect was positively correlated with absorbance measurements of MRP at 350 nm, used as an indicator of the Maillard reaction development.
In order to study if glycosylation plays a role in the formation of protein disulfides and cataractogenesis, the levels of total sulfhydryl, GSH, protein disulfides (PSSP), protein mixed disulfide (PSSG) and the extent of glycosylation has been determined in normal, senile cataractous and diabetic cataractous lenses. No correlation between the extent of glycosylation and the total disulfide, PSSP or PSSG was observed in the normal, senile cataractous or diabetic cataractous lenses. This indicated that glycosylation probably does not play a primary role in cataract formation in diabetic patients.
The mutagenicity for Salmonella typhimurium TA100 without S9 mix of Maillard reaction products (MRP) obtained from equimolar amounts of glucose and amino acids under different pHs was investigated. MRP derived from arginine and lysine exhibited the strongest mutagenicity, and weaker mutagenicity was shown by the mixtures with alanine, serine, threonine and monosodium glutamate. MRP from proline and cysteine had no detectable mutagenicity. Furthermore, glucose-arginine and glucose-lysine reaction mixtures, which presented a marked mutagenicity, showed pH- and browning intensity-dependent expression of their mutagenic activities. The mutagenicity of MRP, especially glucose-arginine and glucose-lysine mixtures, was significantly suppressed by active oxygen scavengers such as cysteine, mannitol, α-tocopherol, catalase and superoxide dismutase (SOD) and reducing agents such as sodium bisulfite and glutathione. Among these desmutagenic factors tested, cysteine, catalase, sodium bisulfite and glutathione had higher desmutagenic activities than the others. Accordingly, it is assumed that the mutagenicity of MRP is due to the direct action of low-molecular-weight compounds such as carbonyls and heterocyclics produced by the Maillard reaction and is enhanced by active oxygens, especially singlet oxygen and hydrogen peroxide derived from their autoxidation.
Browning reactions represent an interesting research area for the implications in food technology, nutrition and health. The development of some non-enzymatic browning reactions, such as Maillard reaction, has been recently associated to the formation of compounds with strong antioxidant capacity. In this paper, the relation between colour changes due to non-enzymatic browning and the formation of compounds with antioxidant activity is discussed. Simple positive or complex correlation between colour and antioxidant properties can be found depending on composition and technological history of the product. Complex relations between these variables are generally obtained in multi-component and in formulated foods, where the simultaneous development of a number of reactions, interacting or prevailing Maillard reaction itself, can affect in opposite ways the overall antioxidant properties and colour of the product.
This paper reviews some of the research designed to lead to an increased understanding of the chemistry of the Maillard reaction, based on recent developments, and its influence on food properties like colour, flavour and nutritional value. A critical analysis is given on how quality attributes associated with Maillard reaction can be predicted and controlled by kinetic modelling. Multiresponse modelling (taking more than one reactant and product into consideration in the modelling process) is a powerful tool to model complicated consecutive and parallel reactions, like the Maillard reaction. Such a multiresponse approach provides a major guidance in understanding the reaction mechanism. An illustrative example is given.
Hemoglobin AIc is a minor component of normal adult erythrocytes whose concentration is elevated approximately 2-fold in patients with diabetes mellitus. Previous work suggested that the unique structural feature of hemoglobin AIc is the presence of a low molecular weight sugar moiety at the NH2-terminal valine of the beta chain. In this study the structure of the carbohydrate moiety and the nature of its linkage of the beta chain were investigated. Enzymatic digestion of borohydride-reduced betaAIc chains followed by ion exchange chromatography led to the isolation of two distinct NH2-terminal glycovalylhistidines. Comparison of these glycodipeptides with synthetic glycovalylhistidines by thin layer chromatography, gas-liquid chromatography, and proton magnetic resonance spectroscopy gave direct evidence that the naturally derived materials correspond to glucitol and mannitol valylhistidines. Model reactions showed that glucose and mannose react with valine under mild conditions to form an adduct which upon sodium borohydride reduction yields in both cases glucitol and mannitol valines. This suggests a common intermediate, 1-deoxy-1-(N-valyl)fructose, for both reactions. From these studies we conclude that hemoglobin AIc has, as the NH2 terminus of the beta chain, 1-deoxy-1-(N-valyl)fructose. The possible biosynthetic pathways of hemoglobin AIc are discussed.
The early soluble premelanoidins are obtained by a wet heat treatment (1 hour at 90 degrees C) of isomolecular quantities of glycine and glucose. It is know that these products decrease the nitrogen digestibility and the biological value of the diet. These premelanoidins are used as a well-balanced ration for the female rats at the rate of 2.15 g of degraded nitrogen by kg of diet. They disturb the reproduction phenomena: -- the fertility of the female is of 56 p. 100 instead of 76 p. 100 in the control females; -- the still-born youngs are twice more numerous and the intrauterine resorptions five time more numerous with the premelanoidin diet than with the control diet; -- the living youngs of experimental litters are 30 p. 100 less important than control litters. Yet, they have an lower weight at the birth and also at the end of the lactation phase. The damages induced by early premelanoidins can be imputed to an antinutritional character. of these substances, or -- more accurately -- to a nitrogen inefficacy that they could provoke. The premelanoidins have not a significant effet on the liver weight, but hypertrophy the kidneys and principally the caecum. The premelanoidin metabolism seems difficult and is similar to the lactose one.
This chapter focuses on the biochemical basis of advanced glycosylation and discusses the diverse effects of advanced glycosylation products in biology and medicine. The chemical and biological conception of the advanced glycosylation process has evolved considerably since early studies on the formation of HbA1c. Despite difficulties in the structural elucidation of advanced glycosylation products, the ensuing years have yielded much insights into the biochemistry of AGEs, in large part assisted by consideration of related pathways in the Maillard reaction. Studies of biological processes have been motivated by the multiorgan pathology that occurs during chronic hyperglycemia. The basis of much of this pathology is still poorly understood. Related investigations of normal, age-related processes are only now beginning to bear insight into some of the clinicopathological sequalae that characterize normal aging. Given the slow, progressive nature of AGE accumulation in vivo and the active cell-mediated processes that appear to be required for AGE removal, it is likely that the investigation of advanced glycosylation mechanisms will continue to provide insight into a variety of additional biological and pathological processes that are characterized by long-term, age-related, and degenerative changes.
Amino-carbonyl Interactions of food constituents encompass those changes commonly termed browning reactions. Such reactions are responsible for deleterious post-harvest changes during processing and storage and may adversely affect the appearance, organoleptic properties, nutritional quality, and safety of a wide spectrum of foods. A growing area of concern is nutritipnal carcinogenesis, in which nutritionally linked cancer has been associated with amino-carbonyl reaction products.
Specific practical and theoretical approaches to prevent adverse effects of food browning include: (1) modification and removal of primary reactants and endproducts in the browning reaction; (2) prevention of deleterious browning reactions through the use of antioxidants; (3) blocking of in vivo toxicant formation from browning products by means of dietary modulation; (4) accurate estimation of low levels of browning products in whole foods and their removal through antibody complexation; and (5) stimulation of inactivation in vivo toxicants from browning products by use of amino acids and sulfur-rich proteins.
Publisher Summary In this chapter, the browning reaction mechanism, and the formation of antioxidants and mutagens are reviewed. The stages in browning reaction mechanism based on Hodge's scheme are described in detail. Different stages are initial stage involving the formation of glycosyl amino products followed by Amadori rearrangement, intermediate stage involving dehydration and fragmentation of sugars and final stage involving aldol condensation, polymerization, and formation of heterocyclic nitrogen compounds. Formation of free radicals and structure of novel free radicals in the initial stage are described in detail. The sugar fragmentation and carbonyl compounds in the formation of free radicals are effective in browning process. The steps in the intermediate stages described are Amadori rearrangement products, enolization and degradation of Amadori products and precursors of melanoidins. The final stage describes the chemistry of melanoidins. The chapter also discusses the antioxidants and Maillard reaction. The stability of foods increases when Maillard reactions occur. The stabilization is considered to be because of the antioxidative action of Maillard reaction products (MRPs). Conditions for induction of antioxidative activity are explained. Detailed explanation about the antioxidative property of reductones is presented. The antioxidative property of reductones is due to their reducing activity and metal cheating ability. Application of MRPs in practical food processing is also highlighted. The relationship between mutagen formation and browning of food is explained. The role of nitroso mutagens and antimutagens is also discussed. The chapter also discusses the need for more detailed information on the structure and properties of melanoidin to elucidate the mechanism of its antioxidative activity.
For an individual, especially a civilized person, the selection of foods is determined largely by flavor. Concern for physical well-being and the nutritional values involved come far behind flavor as a factor determining human dietary choice. The gradual recognition that complex, presumably nonenzymatic transformations, which take place in certain foods, responsible for deterioration in some cases and for the development of traditionally valued flavors in others, have a common chemical basis leading to the carrying out of experiments in relatively simple model systems. The reaction initiating the sequence between a carbonyl group and a trivalent nitrogen atom is the most thoroughly investigated and best understood of all the reactions. Many bland or even downright unpleasant-tasting substances are transformed into some of the most desirable flavors and popular foods by roasting. The enormous variety in flavor is due almost entirely to the large number of permutations from the interactions of a relatively few primary reactants and to the importance of balance among the components finally present. Since humans began to cook meat and bake bread, they have been familiar with the aromas and flavors produced by Maillard browning reactions. The presence and the consumption of products of browning reactions in foodstuffs present two possible problems for human health, one nutritional and the other mutagenic. Investigations in the field of Maillard chemistry are now directed to the solution of an ever-widening circle of problems, which differ more and more from each other, though each is still attached to the core.
This chapter presents a discussion of a considerable amount of new work on the reaction between aldoses and amines. The closely related reactions between uronic acids and amines, and ketoses and amines have been discussed. Earlier work on the reaction between aldoses and proteins in the light of recent work on the reaction between aldoses and simple amines has also been mentioned. Some references to work on the effect of browning reactions on the nutritive value of proteins are considered. Browning reactions involving lipids and amines involved in the browning reactions are discussed. The chapter discusses some reactions that lead to browning in the absence of amines. The investigation of the flavors and odors of foods entered a new phase with the development of gas–liquid chromatography and, more recently, of mass spectrometers that can be linked to gas chromatography capillary columns. These methods have been applied in the field of flavors and odors arising from non-enzymic browning. Investigations dealing with flavoring substances in a variety of cooked and processed foods have been discussed. The development of new methods for the separation and identification of volatile compounds has revolutionized flavor research in recent years. These new methods are being used to study the flavors and odors developed in foods during cooking or processing, and some interesting relationships are emerging. Discussion of the inhibition of browning by chemical methods is concerned with inhibition by sulfites and by thiols. Considerable progress has now been made in elucidation of the mechanism of the action of sulfites on sugars and in browning reactions.