The study of pineapple’s volatile constituents has been the subject of several publications—TNO for Ananas comosus (L.) Merr. contains 21 literature references, and 286volatiles of this fruit have been reported so far. The well-known allyl hexanoate, reminiscent of pineapple fruit, was identified by Drawert and Nitz, in 1982, in fruits from the Ivory Coast and Kenya. Three years later, these authors correlated the analytical data with sensory judgments using gas chromatography sniffing technique, to confirm the contribution of ethyl 3-(methythio)-propionate to pineapple flavor. However, an organoleptic impact of allyl hexanoate to natural pineapple flavor was excluded, due to its low concentration in the fruit and its rather high odor detection threshold. Nevertheless, with a characteristic fruity, sweet and pineapplelike note, this odorant is widely used in the flavor and fragrance industries.
The production of high quality flavors is difficult as raw materials isolated from the fruit are known to be rather weak and not very heat-stable. Over the years, several publications have reported about the volatile composition of pineapple fruits and their concentrated juices, established differences between green and ripe fruits and discussed the contribution of several constituents to the overall flavor. Many hydroxy esters, acetoxy esters and esters containing a methylthio group in the molecule were identified; it’s worth noticing that allyl hexanoate has never been mentioned since Drawert’s work. In a recent study, Ara and Heil could not identify this ester in pineapple using a methodology that had a detection limit of 0.1 μg/L.10 In 2005, Schieberle et al. identified 29 odor-active compounds by application of aroma extract dilution analysis (AEDA) to an aroma distillate prepared from fresh pineapple.9 Calculation of odor activity values (OAVs) indicated the following compounds to be the key odorants: 4-hydroxy-2,5-dimethyl- 3(2H)-furanone, ethyl 2-methylbutyrate, methyl 2-methylbutyrate and 1-(E,Z)-3,5 undecatriene. More recently, GC-olfactometry was also applied by Akioka to determine the characteristic odorants in Philippine pineapple.
The present paper reports, for the first time, the identification of 9-decen-2-one (CAS# 35194-30-0) in pineapple and evaluates its sensory properties. It also proposes a pathway for the molecule’s biosynthesis to explain its production in the fruit.