Furaneol aroma strawberry

From the wine aromas of Pollux, Castor, and Riesling grapes, Rapp et al. and Schreier and Paroschy have isolated an undesirable strawberry aroma by GC-MS (80V13, 81MI112). This lactone was characterized as 2,5-dimethyl-4-hydroxy-2,3-dihydro-3-furanone 8 ("furaneol") having an odor threshold of 50-100 ppb. 

Re, L., Maurer, B., Ohloff, G. A simple synthesis of 4-hydroxy-2,5-dimethyl-3(2//)-fiiranone (Furaneol), an important aroma compound of pineapple and strawberry. Helv. Chim. Acta 1973, 26, 1882-1894. 

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). 

Strawberry flavor The strawberry aroma is made up of caramel-like [ impact compounds Furaneol, mesifuran (see Furaneol )], fruity [ fruit esters, 4-decanolide (see alkanolides)], green [( )-2- hexen-l-ols, ( )-2- hexenals, 2-hexenyl acetate (see fruit esters)], and flowery notes ( linalool, methyl anthran-ilate). Particularly important fruit esters are ethyl butanoate and hexanoate as well as the corresponding methyl esters. Free acids such as 2-methylbutanoic acid (C5H,o02, Mr 102.13, CAS [116-53-0]) and trace substances, e.g., dimethyl sulfide and vanillin, round off the aroma. 

Furaneol and norfuraneol are significant sensorially active substances with low threshold concentrations. They are synthesised and added to numerous aroma compositions with a pleasant sugary, jammy, fruity and caramel flavour reminiscent of cooked strawberries and pineapple, which is where furaneol was identified for the first time (see Section 8.2.11.1.1). 

Pineapple Ananas comosus, Bromeliaceae) aroma consists of about 200 alcohols, esters, lactones, aldehydes, ketones, monoterpenes, sesquiterpenes and other volatiles. About 80% of the total volatile substances are esters. The main components in the green fruit are ethyl acetate, ethyl 3-(methylthio)propionate (8-189) with a distinctive pineapple aroma and ethyl 3-(acetoxy)hexanoate (8-190). The ripe fruit contains, as the main esters, ethyl acetate, (2J ,3i )-butane-2,3-diol diacetate (8-191) and ketone 3-hydroxy-butan-2-one. An important compound for the typical character of pineapple aroma, as in strawberry aroma, is 2,5-dimethyl-4-hydroxy-2//-furan-3-one (furaneol), present as a glycoside, and 2,5-dimethyl-4-methoxy-2H-furan-3-one. 

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