It is the Maillardreaction that makes a roast potato different from a boiled potato and gives French fries, po- tato crisps, bread crust, biscuits, rye crispbreads and a wide variety of other popular foods their characteristic flavour, aroma and texture (Figure 4). As well as the obvious ben- efits of palatability, colour and aroma, the Maillardreaction produces antioxidants, antibiotics and antimutagens. On the bad and ugly side, there are also products with muta- genic, clastogenic and cytotoxic effects, while cross-linked polymers prevent access by proteolytic enzymes, to some extent obstructing digestion. One of the toxic products is acrylamide (Figure 3); this chemical, which is very familiar to biochemists because of its use in gel electrophoresis, was discovered in mainly plant-derived foods as recently as 2002 9 . Acrylamide is neurotoxic, carcinogenic and genoto-
Key intermediates. Furfural and 4-hydroxy-5- methyl-3(2H)-furanone are the two key interme- diates in the Maillardreaction where pentoses are involved. Furfural increased with the pres- sure increasing in the SC-CO 2 -treated reaction mixtures. By comparison, furfural in the SC-N 2 - treated samples was present at such a low level as was that detected in the control. Based on the lower degradation rate of ribose in SC-CO 2 (data not shown), the decrease of pH in the SC-CO 2 - treated matrices during the reaction could inhibit the advanced stage of the Maillardreaction and furfural accumulation. 4-Hydroxy-5-methyl-3(2H)- furanone is derived from the Amadori compound via 2, 3-enolisation pathway favoured in high pH systems (Mottram & Nobrega 2002). At first sight, a slight discrepancy occurred between the decreasing pH in the SC-CO 2 system and the high 4-hydroxy-5-methyl-3(2H)-furanone accumu- lation. Following the conclusion of Mottram and Nobrega (2002), 2,3-enolisation of Amadori compound was catalysed by buffers and the effect of catalysis was greater than any effect of pH. The
Covalent linkage of the Protein – Polysaccharide through non-chemical means such as the Maillardreaction, produces high molecular weight biopolymers known as glycoconjugates. Creation of glycoconjugates is often achieved through conjugation or attachment of a suitable carbohydrate to a particular binding site on the protein. Many of the positive benefits of producing Maillard generated conjugates include improvements in emulsifying activity, foaming properties, calcium complexing, solubility, and heat stability. Emulsion stability enhanced by the use of glycoconjugates can prevent aggregate formation which in turn prevents flocculation and coalescence, processes that can negatively lead to creaming.
Delgado-Andrade C., Rufián-Henares J. A., Morales F. J. (2008): Optimised procedure to analyse Maillardreaction-associated fluorescence in cereal-based products. Czech J. Food Sci., 26: 339–346. Fluorescent Maillard compounds measurement provides more specific information on the extent of the Maillard reac- tion than other unspecific tools to monitor the reaction, and is suitable, as the first approach, to assess the nutritional quality of foods as related to protein damage. This work presents an optimised laboratory procedure for the measure- ment of total fluorescent intermediate compounds (FIC) associated with Maillardreaction, described and evaluated in a cereal-based product. Total FIC are evaluated using increased pronase E concentrations and different incubation times for the enzymatic hydrolysis, as well as three different sample clean-up steps after the enzymatic digestion. The effects of basic/acid media are considered for the stability of the fluorescent compounds. The standardised procedure is finally applied to breakfast cereals as a model of cereal-based products, analysing the correlation between total FIC production and fibre and protein contents. It is demonstrated that fluorescent compounds are mainly linked to the protein backbone in ready-to-eat breakfast cereals. Fluorescence measurement is presented as an inexpensive, rapid and accurate procedure to study the extent of Maillardreaction in breakfast cereals.
During heat treatment, chlorophyll degrades to pheo- phytin, which in turn decomposes to other degradation products. Both chlorophyll and pheophytin conversion can be minimized by the addition of maillardreaction products to improve the colour stability. The present study clearly shows the advantage of using MRP on chlorophyll stabilization and retention in green peas.
Food industries usually resort to the use of synthetic antioxidants to prevent lipid oxidation, although the scientific evidence of their possible toxic effects and the consumers’ preferences for natural products force the meat industry to use naturally occurring antioxidants. In this regard, research works include fruit juices , tea extracts , residues from the wine industry  and different Maillardreaction products such as amino acid- sugar reaction products  , porcine plasma proteins-sugar reaction products  and other protein-alde- hydes reaction products  . The addition of such substances usually darkens the meat product, limiting its use due to the impact on food colour.
To investigate the contribution of glycation and oxidation reactions to the modification of insoluble collagen in aging and diabetes, Maillardreaction products were measured in skin collagen from 39 type 1 diabetic patients and 52 nondiabetic control subjects. Compounds studied included fructoselysine (FL), the initial glycation product, and the glycoxidation products, N epsilon-(carboxymethyl) lysine (CML) and pentosidine, formed during later Maillard reactions. Collagen-linked fluorescence was also studied. In nondiabetic subjects, glycation of collagen (FL content) increased only 33% between 20 and 85 yr of age. In contrast, CML, pentosidine and fluorescence increased five-fold, correlating strongly with age. In diabetic patients, collagen FL was increased threefold compared with nondiabetic subjects, correlating strongly with glycated hemoglobin but not with age. Collagen CML, pentosidine and fluorescence were increased up to twofold in diabetic compared with control patients: this could be explained by the increase in glycation alone, without invoking increased oxidative stress. There were strong correlations among CML, pentosidine and fluorescence in both groups, providing evidence for age-dependent chemical modification of collagen via the Maillardreaction, and acceleration of this process in diabetes. These
Despite the available reports on the phenolic composition and antioxidant capacity (AOC) of beers and malts, there is a scarcity of the published knowledge on the newly formed and/or released antioxidants in the literature. In summary, the Maillardreaction undoubtedly plays a major role in maintaining and developing the reducing power of malt and beer. The changes in the composition of reducing compounds during processing may be due to the degradation or other reactions of indigenous phenolic compounds, the generation of Maillardreaction products (MRPs), and the interaction of phenolics or their degradation products with the MRPs and other components. High-molecular MRPs, melanoidins (> 1 kDa), account for a minor part of electrochemical reducing capacity of both beers and aqueous extracts of malts. In addition to simple phenolic compounds, process-induced 2,3-dihydro-3,5-dihydroxy-6-methyl-(4h)-pyran- 4-one (DDMP) is responsible for a substantial part of the reducing power in several types of malts and beers. Nevertheless, there is still a lack of the data on the stability of the process-induced reducing MRPs and their effects on the redox status and AOC maintaining throughout brewing and storage of beer.
Visual color in processed foods is largely due to colored products of Maillard or nonenzymic browning reactions. In spite of the longstanding aesthetic and practical interest in Maillard derived food coloring materials, relatively little is known about the chemical structures responsible for visual color . These chemical structures are known as Colored MaillardReaction Products and can be isolated at intermediate stages during the melanoidins formation process.
The Maillardreaction (MR), a well-known, non-enzy- matic browning reaction, can produce colored or color- less products from substrates such as glucose-tyrosine, glucose-lysine, fructose-lysine, ribose-lysine, xylose-argi- nine, xylose-glycine, and xylose-tryptophan [22-25]. These products have anti-oxidative [22-24,26], anti- mutagenic , anti-carcinogenic  and anti-bacterial effects . Previous studies have shown that LPS treat- ment of cultured astrocytes causes Ab accumulation through elevation of b- and g-secretase activity and inflammatory reactions . We have shown that 2,4-bis ( p -hydroxyphenyl)-2-butenal inhibits LPS-elevated inflammatory reactions in macrophages (unpublished data). Therefore, in the present study, we investigated whether 2,4-bis( p -hydroxyphenyl)-2-butenal inhibits LPS-elevated Ab levels in cultured astrocytes and micro- glial BV-2 cells, through attenuation of LPS-induced inflammatory reactions, and investigated possible mechanisms of anti-amyloidogenesis.
produced from oxidative degradation of lysine Amadori products, as well as from reaction products of glyoxal and methylglyoxal, respectively, with the ε-amino group in lysine . Both CML and CEL are end products in the MR and have been associated with diabetes . AGEs, may exhibit fluorescence that can be used as indicators of MR progression . At the final reaction stages, MRPs condense and form nitrogen containing polymers and co-polymers, melanoidins, that are responsible for brown colour and can be analysed using UV spectrophotometer .
beta 2-Microglobulin (beta 2M) is a major constituent of amyloid fibrils in hemodialysis- associated amyloidosis, a complication of long-term hemodialysis patients. Amyloid fibril proteins were isolated from connective tissues forming carpal tunnels in hemodialysis patients with carpal tunnel syndrome. Two-dimensional polyacrylamide gel electrophoresis and Western blotting demonstrated that most of the beta 2M forming amyloid fibrils exhibited a more acidic pI value than normal beta 2M. This acidic beta 2M was also found in a small fraction of beta 2M in sera and urine from these patients, whereas heterogeneity was not observed in healthy individuals. We purified acidic and normal beta 2M from the urine of long-term hemodialysis patients and compared their physicochemical and immunochemical properties. Acidic beta 2M, but not normal beta 2M, was brown in color and fluoresced, both of which are characteristics of advanced glycation end products (AGEs) of the Maillardreaction. Immunochemical studies showed that acidic beta 2M reacted with anti-AGE antibody and also with an antibody against an Amadori product, an early product of the Maillardreaction, but normal beta 2M did not react with either antibody. Incubating normal beta 2M with glucose in vitro resulted in a shift to a more acidic pI, generation of
There are eight foods that contribute to food allergies in the western world and peanut is the most common. Currently, there are no medical treatments that can cure an individual of food allergy, so avoidance of the allergic food is the only option. In the United States, there are three immunodominant allergic proteins accountable for patient sensitization to peanut, Arachis hypogea 1, 2, and 3 (Ara h 1, Ara h 2, Ara h 3). Therefore, research into why peanuts are more allergic than other foods that have homologous proteins is critical and may be obtained by studying the structural and allergenic properties of individual allergens and the changes that occur due to food processing. In this study, the basic and acidic subunits of Ara h 3 were cloned, expressed, and purified, and compared with each other and with the native Ara h 3 purified from peanut for differences in binding to IgE from peanut allergic individuals. Also, an in vitro Maillardreaction was performed on purified native raw Ara h 3 and patient serum IgE western blots were performed. This study concluded that an in vitro Maillardreaction enhanced IgE binding to Ara h 3, IgE binding to native Ara h 3 was in most cases higher than to the recombinant Ara h 3 subunits, and recognition of the acidic subunit was much higher than the and basic subunits in both the recombinant and native forms of the protein were investigated.
While additives such as carbohydrate may be employed to improve thermal and dehydration stability of some products, such additives should not strongly change physical and chemical properties of original products. In this context, research about effects of different additives on storage properties of CW powders appears to be greatly valuable. Storage stability of CW powders with different additives was more or less changed due to change of product components. Addition of sugars in CW powders may change adsorption characteristics of original products, which will impact the storage ability of the products. For example, the phenomena that most sugars can spontaneously adsorb amounts of water vapor from storage environment have been reported in pharmaceutical industry [14,15] . During storage, additives in CW powders could react with components in original products or accelerate the rate of certain reactions, such as Maillardreaction  , which is undesirable in these products. Storage stability of CW powders with different additives during different storage conditions receives more attention from producers and end users.
We investigate the effects of consumption of MRPs from the glucose-lysine model system heated 15°C-90 min on protein digestibility and its utilisation in young (3-week) and adult (12-week) rats. Nitrogen faecal excretion signifi- cantly increased after MRP consumption, especially during the third week. Protein digestibility was lower in both age groups studied, but the utilisation was unaffected. Parallelly, the nitrogen retention and its net utilisation for the entire experimental period did not vary. In young rats the faecal nitrogen exceeded the amount of ingested nitrogen coming from MRPs, suggesting that digestibility of undamaged nitrogen was affected. The same action is suspected in adult animals, but the results were not quantitatively conclusive, and therefore the effect should be moderate in this period. Keywords: protein; net protein utilisation; Maillardreaction products; young rats; adult rats
Yazici, 2014) before HPLC-UV analysis. Be- sides these low molecular weight compounds, during the development of the Maillard reac- tion, fluorescent compounds and brown pigments are also formed (Matiacevich & Buera, 2006). The behavior of these easy to measure com- pounds, as adequate Maillardreaction markers, depends on the reaction conditions and the sys- tem’s composition. Since the total amount of fluorescent compounds is the sum of those which are free and those bound to proteins (Delgado- Andrade, Rufian-Henares, & Morales, 2006), the analytical determination has previously been im- proved with a first stage of protein hydroly- sis with pronase (consisting on a mix of prote- olitic activities) in order to completely release the crosslinked moieties (Delgado-Andrade et al., 2008; Farroni & del Pilar Buera, 2012). The pronase treatment had initially been proposed to measure brown pigments in dairy products (Palombo, Gertler, & Saguy, 1984). On this ba- sis, it could also be expected that the same hy- drolytic procedure could improve the extracted amount of furfural family compounds, since po- tential furfurals include free furfurals, furfurals bound to proteins (like Amadori products) and those formed from precursors (Chavez-Servin et al., 2006). From food safety and nutrition stand- points the availability of adequate extraction and quantification methods for furfurals is necessary to ensure better control and safer processing. The aim of this work was to analyze the effec- tiveness of protein hydrolysis with pronase as a pretreatment for the evaluation of furfural inter- mediates during toasting of cornflakes and the parallel development of brown and fluorescent compounds.
ABSRRAC- In recent years, several oconjugation protocols have been developed to improve the functional properties of the enzyme lysozyme. In this study, the optimum conditions of lysozyme – oxidized inulin conjugation and functional properties of the modified lysozyme were investigated. Initially, inulin (MW about 25 kDa) was oxidized by periodate to provide the reactive carbonyl groups to attach to amino groups of lysozyme for Maillardreaction and was then conjugated to the enzyme at a molar ratio of oxidized inulin to enzyme of 5:1. A number of studies were conducted to investigate the optimization of lysozyme – Inulin conjugation consisting of different pH levels (3, 7, and 9), different temperatures (40, 60, and 80°C), and different reaction times. The degree of modification was determined by SDS-PAGE and sugar analysis of the product. The best condition for conjugation was determined to be 60°C at pH 7.0 for one week. The results showed that under these conditions, the inulin-lysozyme conjugate had 58% of the lytic activity of the native enzyme and had better emulsifying properties and heat stability than native lysozyme. Moreover, there was significantly higher protein solubility at pH 7.0 and 9.0 at different temperatures than heated lysozyme. Taken together, the results of this study indicated that lysozyme modification by oxidized inulin results in a new product with improved functional properties which may be employed for different industrial purposes.
One of the most important parameters to which consumers are sensitive when selecting foods is the colour. Manufacturing and preservation processes often degrade the colour of food (Gimenez et al. 2001). The relatively rapid deterioration of the attractive red colour of freshly made strawberry preserves has been a persistent problem. Colour deterioration is due to at least three factors: the loss of red anthocyanin pigment, formation of brown pigments, and discoloration through fac- tors such as heavy metal contamination (Abers & Wrolstad 1979). Anthocyanins have a crucial role in the colour quality of many fresh and proc- essed fruits. They are a good source of natural antioxidants, however, they are quite unstable during processing and storage. The temperature, pH, oxygen, and water activity are considered to be important factors influencing their stability. During heating, degradation and polymerisation usually lead to their discoloration. It has been proven that some degradation products of an- thocyanins have the antioxidant capacity (Tsai & Huang 2004). Maillardreaction products have also been proven to be powerful as antiradical agents (Manzocco et al. 2001). The degradation of sucrose and anthocyanins during heating may affect both the colour and antioxidant capacity (Tsai et al. 2005).
Coping with the maillardreaction food and the effects of the reaction products on health is important to the improvement and development of food products. The maillardreaction has positive as well as negative aspects in food industry. The positive contributions of the maillardreaction are sensory attributes generation, such as color, flavor, aroma and texture. The negative aspects are off-flavor development, flavor loss, discoloration, and loss of protein nutritional value. In the food industry, the role of flavor and color either desirable or undesirable is the key in the manufacture of products of consistent sensory quality. Contradictory knowledge about the effects of maillardreaction products on health indicates that studies are needed to further expand the AGEs and MRPs database as well as development of methods for reducing MRPs generation during home cooking and food processing. Understanding the chemical, nutritional and toxicological consequences of browning reactions and related transformations, in vitro and in vivo, can lead to better and safer foods and improved human health.