2.5- Dimethyl-4-methoxy-3 -furanon

Low concentrations of ethyl-2-and 3-mercapto-propionate, mentioned earlier in this chapter, have a fruity aroma, whereas in larger quantities they have sulfurous smells. Acree et al. (1990) also demonstrated the presence of 2-amino-acetophenone in Vitis labrusca, as well as two furanones (4-hydroxy-2,5-dimethyl-3-furanone, commonly known as furaneol, and 4-methoxy-2,5-dimethyl-3-furanone) reminiscent of strawberries (Rapp et al., 1980). Most of these compounds have also been identified in Vitis vinifera wines, but at lower concentrations (Guedes de Pinho, 1994 Moio and Etievant 1995). 

Methoxy-2,5-dimethyl-3(2H)-furanone [2H3]methoxy Schieberle and Hofmann, 1997... 

Numerous studies on the volatile compounds of Vitis vinifera wines, as reviewed by Webb (5), Schreier 4) and Rapp (5), helped to elucidate the basic flavor chemistry in this field of special interest. Enormous efforts were focused on the topic of varietal characterization (d). With regard to the analytical differentiation of the varietal aroma or "bouquet two points of view are important. First of all it is necessary to understand the influence of specific compounds on the total flavor impression. Secondly aroma chemicals are of fundamental interest for the study of breeding experiments. A good example for this approach is the identification of 2,5-dimethyl-4-hydroxy-3(277)-furanone and its methoxy derivative in berries and wines of some interspecific grapevine breedings (7). 

DIMETHYL-3-HYDROXY 3(2H)>FURANON 5-METHYL-2-ETHYL-4-HYDROXY 3(2H)-FURANON 2,5-D METHYL-4-METHOXY 3(2HFFURANON 3-METHYL CYCLOPENT -2-EN-2-OL-1-ON... 

Cyclopentenolones with a planar vicinal enol-oxo configuration are known to be powerful aroma active substances with distinct caramel notes. By methylation of the enolic function, this flavour impression is changed drastically to a sweet, mildew, and mouldy odour in the case of 2,5-dimethyl-4-methoxy-3-[2H]-furanone (2). This so-called mesifurane as well as pineapple ketone (1) were stereodifferentiated with modified cyclodextrin [103], Although (1) and (2) can be stereoanalyzed without any racemization, both compounds were detected in strawberries, pineapples, grapes and wines as racemates (Fig. 6.43). 

Numbers correspond to those in Tables HI and IV. Odor quality as perceived during GCO. Retention indices calculated from GCO data, FFAP = Stabilwax DA column. Average logs flavor dilution (FD) factor (n = 2), neutral/basic fraction determined on DB-5MS and acidic fraction determined on Stabilwax DA column. Con ound tentatively identified based on con arison of odor property and retention indices with reference conq)ound. 2,5-dimethyl-4-hydroxy-3(2 -furanone. 3-hydroxy-4,5-dimethyl-2(5/0 ft iione. 3-methoxy-4-hydroxybenzaldehyde... 

Mesifuran [4-methoxy-2,5-dimethyl-3(2//)-furanone], C7H10O3, Mr 142.15, often occurs together with F. and is responsible for the characteristic aroma of the blackberry species Rubus arcticus. ... 

Hydroxy-3-methoxy-4,8-dimethyl-1,4-decadienyl)-5-methyl-2(5//)-furanone, see A-20172... 

An example of a furanone with methylated hydroxyl in position C-4 is 4-methoxy-2,5-dimethyl-2H-furan-3-one, also known as mesifurane, which is derived from furaneol. (-F)-(R)-Mesifurane (8-163) has a burnt and caramel-Hke odour, but is more subtle and mellow than the odour of furaneol. Mesifurane accompanies furaneol in fruits (such as pineapple, raspberry, strawberry and grape) and other foods. 2,5-Dimethyl-2H-fiiran-3-one, which does not contain the C-4 hydroxy group occurs as a constituent of bread and coffee flavour its odour resembles bread. 

Nowadays, more than 400 compounds forming the large-fruited strawberry Fragaria ananassa and other hybrids, Rosaceae) flavour are known, yet the importance of many of them is not yet fuhy understood. Besides a number of esters (mainly butanoates) and aldehydes, such as (Z)-hex-3-enal, which generally have green and fruity flavours, 4-hydroxy-2,5-dimethyl-2 f-furan-3-one (furaneol, also known as strawberry or pineapple furanone) and its methyl ether 4-methoxy-2,5-dimethyl-2 f-furan-3-one... 

Diethylresorcinol. 2,4-Diethyl-l,3-benzenediol, 922 4,6-Diethylresorcinol. 4,6-Diethyl-l,3-benzenediol, 922 Dihydroeugenol acetate. 2-Methoxy-4-propylphenyl acetate, 927 Dihydrousnic acid. 2,6-Diacetyl-3,7,9-trihydroxy-8,9b-dimethyl-l-(4H,4aH,9bH)-dibenzo-furanone, 111... 

The phenomenon of adsorption/instability of enoloxo compounds during GC analysis is illustrated in Fig. 14. Furaneol and its methylether were analyzed at different concentrations by diluting the samples 1 1, i.e., FD-1, ED-2, FD-4, and FD-8. The chromatography of 4-methoxy-2,5-dimethyl-3(2i/)-furanone (no. 1) was not affected by the stationary phase. On the contrary, furaneol (no. 2) was partially lost on SE-54. Chromatographic behavior on FFAP was acceptable. 

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