Maillard reaction furaneol

Schwab W. (1998) Application of stable isotope ratio analysis explaining the bioformation of 2,5-dimethyl-4-hydroxy-3(2//)-furanone in plants by a biological Maillard reaction. (Furaneol). J. Agric. Food Chem. 46, 2266-9. 

Heating also produces a series of other substances as a result of Maillard reactions. These include cyclotene, maltol and its derivatives (hydroxymaltol, dihydro-maltol), 2,3-dihydro-5-hydroxy-2-methyl4(/7) pyranone (DHM) and its 5-hydroxy derivative (DDMP) and furaneol. The sensory impact of these components can play an important role in developing the toasted , burnt , or caramel aromas of some barrel-aged wines (Cutzach et al. 1997,1999). 

A particularly important aroma compound formed from reducing sugars during the Maillard reaction is 4-hydroxy-2,5-dimethyl-3(2/f)-furanone (26, Furaneol). It is a... 

Furaneol is formed when the sugar rhamnose is heated in the presence of a substance containing an amino group through a Maillard reaction (Fig. 3.62). HMF results from heating of fructose (Fig. 3.63). Both furanones occur in various foods. For example, Furaneol has been identified in pineapple, strawberries and popcorn both Furaneol and HMF have been found in meat broth [21 [. Both furanones are applied as flavour modifiers in foods where maltol and ethyl maltol are used [1[. 

Its formation from rhamnose heated with piperidine acetate in ethanol, under the same conditions that produced amino-hexose-reductones from glucose and other hexoses, was described as early as 1963 by Hodge et al., who confirmed the structure by IR and NMR data and proposed a formation pathway. The formation from Amadori intermediates was been reviewed by Vernin (1981). Numerous model systems have confirmed that it is one of the main Maillard-reaction products. For instance we will mention the formation from L-rhamnose and ethylamine (Kato et al., 1972) and from pentose/glycine or alanine, whose mechanism was proposed by Blank and Fay (1996) and Blank et al. (1998), from the intermediate Amadori compound, /V-(l-deoxy-D-pentos-l-yl)glycine. Furaneol is also formed by recombination of... 

Kato et al. (1972) have shown that it is formed in a Maillard reaction of L-rhamnose with ethylamine, the most abundant product being Furaneol (1.100). The proposed formation pathway involves a 1,2-enaminol of L-rhamnose. 

In addition, other work showed that 3-hydroxy-4,5-dimethyl-2(5H)-furanone can be formed thanks to a Maillard reaction of hexoses and pentoses in the presence of cysteine 20). Due to the non-linear structure of Sotolon, its formation cannot simply be explained directly from sugar cyclization during tire Maillard reaction, like other furanones such as Furaneol. Hence, it is likely tliat Sotolon results from rearrangement of Amadori products of low molecular weight like butan-2,3-dione (diacetyl) and hydroxyacetaldehyde, via an aldol condensation (Figure 6). 

An important compound is 4-hydroxy-5-methyl-2H-furan-3-one, known as norfuraneol. Norfuraneol occurs in caramel, roasted chicory root and also in meat broth. 4-Hydroxy-2,5-dimethyl-2H-furan-3-one, known as furaneol, strawberry furanone or pineapple furanone, arises in the Maillard reaction from L-rhamnose (Figure 4.39) and in a reaction of methylglyoxal with hydroxyacetone (Figure 4.41). It occurs, for example, in strawberries, pineapple, roasted almonds, popcorn, meat broth and a number of other foods as a racemic mixture. The structure of (+)-(J )-furaneol responsible for the characteristic odour is given in formula 8-160. The odour of furaneol is sugary, jammy and reminiscent of strawberries and, at higher concentrations, caramel (threshold concentration is... 

Raw or gently pasteurised milk (e.g. for 10 seconds at 73 °C) has a fine characteristic odour and sweet taste. Typical components present in low concentrations are dimethylsulfide, biacetyl, 2-methylbutan-l-ol, (Z)-hept-4-enal and ( )-non-2-enal. Milk pasteurised at higher temperatures and Ultra High Temperature (UHT) milk present the so-called cooked flavour, the appearance of which is the first measurable manifestation of the chemical changes that occur in heated milk. The substances responsible for the cooked off-flavour are sulfane and other sulfur compounds. Of particular importance are dimethylsulfide, dimethyldisulfide and dimethyltrisullide that are produced from proteins contained in the membranes of fat particles and from thiamine. Also relevant are alkane-2-ones (methylketones) generated by thermal decarboxylation of P-oxocarboxylic acids (mainly hexane-2-one, heptane-2-one and nonane-2-one), y-lactones and 5-lactones produced by dehydration of y- and 5-hydroxycarboxylic acids (mainly 8-decalactone and y- and 8-dodecalactones). Important carbonyl compounds include biacetyl, hexanal, 3-methylbutanal, (Z)-hept-4-enal and ( )-non-2-enal. In the more intensive thermal treatment of milk (sterilisation), products of the Maillard reaction play a role, such as maltol and isomaltol, 5-hydroxymethylfuran-2-carbaldehyde, 4-hydroxy-2,5-dimethyl-2 f-furan-3-one (furaneol) and 2,5-dimethylpyrazine. 

Cocoa flavor. Some of the over 500 known volatile components of C. f. are already present in raw cocoa, but most are formed after diying and roasting (at 110-130 °C), mainly by Maillard or Strecker reactions from amino acids, peptides, and sugars resulting from anaerobic fermentation. C. f. is not determined by one impact compound but is rather a composition of various aromas caramel-like ( maltol, Furaneol , and 2-hydroxy-3-methy 1-2-cyclopenten-1 -one), flowery ( linalool, 2-phenylethanol, phenylacetaldehyde). 

Recently, furaneol and homofuraneol were detected by GC-0 in Maillard model reactions based on pentoses and different amino acids. This initiated a systematic study to explain these surprising findings (30). As shown in Fig. 11, the Strecker aldehydes of glycine and alanine were actively involved in the forma-... 

---