Cider Aroma


Here's a bit of chemical information on cider aroma - that is, the part of the flavour which is perceived by the receptors in the nasal cavity  (e.g. green and fruity notes) rather than those on the tongue (e.g. acid and astringent notes).

It's a link to some work which I carried out in the late 1980's although it was never formally published in a scientific journal.   I did present it though as a poster at the Apple Processing Symposium in Rennes, France, in 2005.  What we did was 'odour-port dilution analysis'.  That's a technique where we made an aroma extract from a cider and then ran it through a GC (gas chromatograph) connected to an odour-port so we could sniff the molecules coming out.  By progressively diluting the extract and re-running it, we eventually got to a point where nothing more was detectable. From the threshold dilution for each molecule, we could calculate the relative contribution of each one to the cider aroma.  We also did conventional GC-MS  (Gas Chromatography coupled to Mass Spectrometry) to identify each of the individual molecules in the chromatogram.  Of course there had been lots of good and very detailed previous studies of cider aroma components by the Long Ashton team led by Tony Williams in previous years, but  no odour-port dilution analyses had been carried out before.

It turned out from our work that the most odour-active molecule was one of molecular mass 172 but of unknown composition. In fact this component had been recognised in cider several times previously but nobody had been able to work out its structure. In a book chapter in 1995, I suggested that it might result from the cyclic condensation of acetaldeyhde with 1,3 octanediol to give a dioxolane, because that was likely to happen during fermentation and would give a molecule of the correct mass.  Its proper name is 2-methyl 4-pentyl 1,3-dioxane. Shortly afterwards, a European team confirmed that this was the right structure and that it did have a 'green' sort of aroma (Ref 1). Not only that, but there's a whole family of related compounds in cider (Ref 2) and, because they derive from a very unusual set of precursors, they're likely to be almost unique to cider (and maybe perry (Ref 3)).  Interestingly, one of the European team working for Pernod-Ricard, who were at that time big in cider and soft drinks, actually patented the production of these dioxolanes as aroma chemicals (Ref 4). The patent is particularly interesting since it shows that the 1,3 octanediol precursor increases with fruit storage time and with incubation / maceration. However, nobody so far as I know has repeated our work to show that the dioxolane is the most odour-active molecule in cider, nor that it has a specifically 'cidery' aroma. It would be a great student project for someone in a University Food science department!

Anyway here's the link (a 160 kB PDF file)  to the poster paper I gave about it in Rennes

And here's a link (1.2 MB Word file) to a formal write-up of the same work, with some more detail.

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References:

1. Claudia Dietrich, Till Beuerle, Barbara Withopf, Peter Schreier, Pascal Brunerie, Carlo Bicchi, and Wilfried Schwab  "Absolute Configuration and Conformation of 1,3-Dioxanes from Cider " J. Agric. Food Chem., 45 (8), 3178 -3182, 1997

2. Dominique Kavvadias, Till Beuerle, Martina Wein, Barbara Boss, Thorsten König, and Wilfried Schwab  "Novel 1,3-Dioxanes from Apple Juice and Cider"  J. Agric. Food Chem., 47 (12), 5178 -5183, 1999

3.  Till Beuerle, W. Schwab  "Octane-1,3-diol and its derivatives from pear fruits"  Zeitschrift für Lebensmitteluntersuchung und -Forschung A  Volume 205, Number 3 / September, 1997

4. US Patent 6384243  "Method for producing natural diol 1,3 derivatives and corresponding 1,3 dioxane derivatives"  Granted May 7, 2002 to Pascal Brunerie (Pernod Ricard)

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Page last edited 3rd June 2007.