Maillard reaction mixtures

Figure 4. N,N -Disubstituted pyrazine cation radicals with assignments for hyperfine structures of the ESR spectra in the Maillard reaction mixtures.

Evers, et al. (34) identified several S-substituted furans having meaty aroma including 3-mercapto-2-methylfuran and 3-mer-capto-2,5-dimethylfuran from Maillard reaction mixtures. These compounds were readily oxidized to sulfides, some of which retained meaty odors. All furans having the sulfur atom bound to the 8-carbon had meaty aromas, whereas those with sulfur bound to the a-carbon had hydrogen sulfide-like odors. 

Table II summarizes the yield and the antioxidative effect of products obtained in the various steps in the purification of the antioxidants from histidine and glucose. The yield is expressed as percent of the starting material, the crude Maillard reaction mixture. The antioxidative effect of the various fractions is compared to that of the crude reaction mixture on a weight basis, the crude reaction mixture being given the value 1. The relative antioxidative effect of 6 for the retentate means, for example, that the retentate gives the same antioxidative effect as the crude reaction mixture with only one sixth of the amount of material. In the table is also shown the calculated "total antioxidative effect" ("yield " x "relative antioxidative effect").

Figure 1. Number of heterocyclic compounds reported in the Maillard reaction mixtures.

Table I. Relative concentrations of some heterocyclic compounds from cysteine + ribose Maillard reaction mixtures containing different lipids...

Kinae, N., Isolation of beta-carboline derivatives from Maillard reaction mixtures that are mutagenic after nitrite treatment, Dev. Food Sci., 13, 343, 1986. 

It may be formed during roasting by reaction between hydrogen sulfide and 2-furaldehyde or furfuryl alcohol. It has been found as the main product (see 1.120 and also the thiophenone J.25) formed in the Maillard reaction mixture cysteine/ribose (Whitfield et al., 1988). By studying and roasting different fractions of raw coffee, it was recently shown that 2-furanmethanethiol is formed by reaction of cysteine with arabinose, the only pentose occurring in raw coffee in considerable amounts (Grosch et al., 2000). 

Morales, F.J. and Babbel, M.B. Antiradical efficiency of Maillard reaction mixtures in a hydrophilic... 

Origin of the volatile and reactive short chain carbon fragments such as glyoxal, pyruvaldehyde and 2,3-butandione formed in Maillard reaction mixtures is relatively diffi-... 

A cytotoxic activity and the ability to induce nuclear translocation of transcription factor NF-kB were identified as important cellular reactions when cells are stimulated by Maillard reaction mixtures or food items such as coffee, which are rich in Maillard products Both cellular effects, however, were fully or at least partially abolished, when coffee extracts or Maillard reaction mixtures were administered to the cells together with catalase. These results indicate that Maillard reaction products are able to generate H2O2, which then induces cellular reactions, such as cell death or immunomodulation. 

AMINOREDUCTONES AS POTENT H2O2-GENERATORS IN MAILLARD REACTION MIXTURES... 

Aminoreductones have been identified as potent components of Maillard reaction mixtures that induce cellular effects through the formation of hydrogen peroxide. On the other hand, the antioxidative effect of Maillard products is well established. The extent of anti-oxidative and pro-oxidative activity of Maillard products seems to depend on the reaction conditions. Thus, it is difficult to differentiate clearly between the physiological and technological effects of oxidation and glycation reactions in processed food. 

The aroma volatiles produced in the Maillard reaction have been classified into three groups by Nursten [6], and this provides a convenient way of viewing the origin of the complex mixture of volatile compounds derived from the Maillard reaction in foods ... 

The disadvantage of the dilution of extracts is that the flavour concentration is lower and the flavour dose has to be increased. Significant heat treatment can influence the flavour stability in a negative way because oxidation and Maillard reactions are enhanced and the flavour might be less stable. Owing to the fact that flavours are mainly complex mixtures, their rheological properties, particularly in presence of hydrocolloids, fibres or other macromolecules, are often not Newtonian. This can cause problems in the production process. In order to simplify... 

Formation of mainly two-carbon fragmentation products of sugars at an early stage of the Maillard reaction implies the presence of residual product(s) of the fragmentation in the reaction mixture. To demonstrate this, the reaction mixture of D-glucose with n-butylamine in ethanol was treated at the initial stage with NaBHi, and then acetylated for GLC analysis. As shown... 

Formation of novel free radical products at an early stage of the Maillard reaction was demonstrated by use of ESR spectrometry. Analyses of the hyperfine structures for various sugar-amino compound systems led to the conclusion that the radical products are N,N -disubstituted pyrazine cation radicals. These new pyrazine derivatives are assumed to be formed by bimolecular condensation of a two-carbon enaminol compound involving the amino reactant residue. The presence of such a two-carbon product in an early stage reaction mixture of sugar with amine was demonstrated by isolation and identification of glyoxal dialkylimine by use of TLC, GLC, NMR, MS and IR. 

In their recent comprehensive review of natural and synthetic meat flavors, MacLeod and Seyyedain-Ardebili (20) listed 80 patents describing "reaction products" procedures that produced meat-like flavors upon heating. Approximately one-half of these precursor mixtures included amino acids and reducing sugars. Most of the mixtures described in patented procedures for synthetic meat flavor are modeled after ingredients found in the water-soluble dialy— zable fraction of fresh meat. These constituents serve as reagents for Maillard reactions. 

Even though many compounds discussed in the above presentation are thought to be important in meat flavor, a delicate blend of these compounds and other ingredients at the appropriate concentration is needed to synthesize acceptable flavor. In view of the possible instability of the flavor compounds themselves, precursors that supply the precise mixture of volatiles upon heating will be needed. Attempts have already been made to use this approach as judged by the numerous patented mixtures of precursors listed in the literature. More effort should be given to the quantitative aspects of meat flavor production and work must be continued on the qualitative aspects of the volatiles and the appropriate Maillard reaction precursors chosen. 

Maillard reaction products were obtained by refluxing 100 ml of distilled water containing 0.1 mol L-histidine monohydrochloride mono-hydrate and 0.05 mol D-glucose for 20 h. The pH of the reaction mixture was adjusted to 7.0 with potassium hydroxide before starting the reaction. 

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