Presence Of Acrolein Derivatives In A Rum Of Abnormal Taste

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Dubois P., Parfait A., Dekimpe J., 1973. Présence de dérivés de l’acroléine dans un rhum à goût anormal. Annales de Technologie Agricoles 22, 2, 131–135.

This is part of a series where French language papers related to the production of fine rums are translated to help emerging industry and celebrate the work of great scientists. I translated everything with google then did a little minor poetic rendering. What is interesting is that the end has abstracts in English, Spanish, and Italian, and that much of the bibliography comes from the whiskey industry illustrating that the faults they are studying overlap.

Station de Technologie des Produits végétaux,
Centre de Recherches, I. N. R. A.,
B.V. 1540, 21034 Dijon Cedex
* Station de Technologie des Produits végétaux, I. N. R. A.,
97.170 Petit-Bourg

A rum with an abnormal taste was analyzed by gas chromatography and mass spectrometry. Two compounds were identified as 3-ethoxypropanal and 1,1,3-triethoxypropane, in addition to ethanol of acrolein. These compounds have already been found in “peppered” whiskeys whose abnormal taste also comes from the formation of acrolein during fermentation.

Key words: rum, acrolein, aroma, gas chromatography, mass spectrometry.

The presence of an abnormal taste was reported in some freshly distilled rums. Their pungent smell disappears through aeration, but at the end of tasting we can perceive a taste that tasters have described as “phenolic” or “pharmaceutical”. This is what distillers call the taste of the still, which disappears after a longer or shorter time.

Material and Methods

A 500 ml sample of aerated peppered rum, freshly distilled and shipped to Martinique in a glass bottle, was redistilled until almost complete removal of the ethanol in a glass apparatus with a Vigreux column of 5o cm. The distillate, rediluted with an equal volume of water, had a normal taste, and the analysis focused on the residue.

By extraction with diethyl ether and total evaporation of this solvent, we obtained a few tenths of a ml of a concentrate having a strong smell of rum, but of unpleasant taste, even after dilution in a alcoholic-water solution at 50 ° GL. This concentrate was analyzed in gas chromatography-mass spectrometer coupling under the conditions indicated in Table I.

The beginning of the chromatogram obtained is shown in FIG. I. Two unusual peaks surround the peak of 2-methylbutanol and 3-methylbutanol which are not separated on the liquid phase used. The mass spectrum of compound A, which is indicated in FIG. 2, is in good agreement with that published by Stenhagen et al. (I969) for 3-ethoxypropanal. The peaks M + —1 (m/e = 101) and M+—44 (m/e = 58) are characteristic of aliphatic aldehydes, although here the hydrogen rearrangement leads to the formation of the peak M+— 44 is done by a way a little different from that which is conventional, because of the presence of oxygen in the gamma position. The peak M+—28 (m/e = 74) corresponds to the loss of one molecule of ethylene and is nothing other than the parent peak of 3-hydroxypropanal (Figure 3). This compound breaks up in turn to give the ions at m/e = 73 (loss of a hydrogen), at m/e = 45 (+CH2-CH2-OH) and at m/e = 31 (CH2 = +OH). In the case of 2-ethoxypropanal, the peak at m/e = 45 should logically be more intense than the peak at m/e = 31.

Compound B (Figure 1) is the acetal of this aldehyde: triethoxy-1, 1,3 propane. The retention volumes and the mass spectra of the two compounds were verified by analysis of the corresponding synthetic products.

Discussion and Conclusion
Maarse and ten Noever de brauw (1966) reported the presence of 2-ethoxypropanal in rums, but it is more likely that it is 3-ethoxy propanal as indicated by Kahn et al. (1968, 1969) in the case of so-called “peppered” whiskeys. This ethoxy-propanal is formed by the addition of ethanol to the double bond of acrolein (Kahn, Laroe and Conner, 1968), during which the ethoxy radical is attached to the carbon atom having the lowest electron density, that is to say in position 3 in the case of acrolein. There is every reason to believe that this reaction occurs during distillation, when acrolein is in the presence of a high concentration of ethanol and at high temperature.

The production of acrolein has been studied during the alcoholic fermentation of wines since Pasteur showed, in 1886, that it was formed at the expense of glycerol, because of the metabolic activity of certain facultative anaerobic bacteria. More recently, this problem has been studied in the case of “peppered” whiskeys by Mills, Baugh and Conner (1954) and by Serjak et al. (1954).

However, neither 3-ethoxypropanal nor triethoxy-1,3 propane appears to have the abnormal taste of the rum studied, even after dilution of these products in ethanol at 5o°GL. Now, it suffices to distill a mixture of water, ethanol and acrolein, to aerate the distillate and to dilute it with an equal volume of water to obtain the desired abnormal taste.

Thus, the abnormal taste observed, on the one hand, and the presence of 3-ethoxypropanal and 1,1,3-triethoxy propane, on the other hand, are both related to the presence of acrolein in the base wine. As for acrolein remaining free, it must be found in the distillation heads or have been removed from the distillate during aeration.

Other derivatives of acrolein may be present, but they could not be highlighted either by the detector of the chromatograph, or olfactory at the column outlet.

Received for publication in May 1973.

A rum, which presented an off-flavour, has been analysed by gas chromatography and mass spectrometry. Two compounds were identified to 3-ethoxy propanal and 1,1,3-triethoxy propane, which are addition products of ethanol on acrolein. These compounds have already been identified in peppery ) whiskies, whose off-flavour originates also from the formation of acrolein during the fermentation. [original English language abstract from the end]

Un ron que presentaba un sabor anormal ha sido sometido a análisis por cromatografía en fase gaseosa y espectrometría de masa. Han sido identificados dos compuestos, el etoxi-3propanal y el trietoxi-1,1, 3 propano, productos de adición del etanol sobre la acroleina. Estos compuestos han sido encontrados ya en los whiskis « pimentados » cuyo sabor anormal procede también de la formación de la acroleina durante la fermentación.

RIASSUINTO [and now in Italian!]
Un rum con sapore anormale è stato analizzato mediante gas-cromatografia e spettrometria di massa. Si son trovati due composti : etossi-3 propanale e trietossi-I, I, 3 propano, prodotti d’addizione dell’ etanolo sull’acroleina. Questi composti sono stati già trovati in whisky «pepati) il cui sapore anormale è dovuto egualmente alla formazione d’acroleina durante la fermentaZIOIle.

KAHN J. H., LAROE E. G., CONNER H. A., 1968. Whiskey composition : identification of components by single-pass gas chromatograph-mass spectrometry. J. Food Sci., 33, 395-4oo.

KAHN J. H., SHIPLEY P. A., LAROE E. G., CoNNER H. A., IQ69. Whiskey composition : identification of additional components by gas chromatography-mass spectrometry. J. Food Sci., 34, 587-591.

MAARSE. H., ten. No EVER DE BRAUW M. C., 1966. The analysis of volatile components of Jamaica rum. J. Food Sci., 31 (6), 95 I-955.

MILLS. D. E., BAUGH. W. D., CONNER H. A., I954. Studies on the formation of acrolein in distillery mashes. Appl. Microbiol., 2 (II), 9-13.

SERJAK W. C., DAY W. H., VAN LANEN J. M., Boruff C. S., 1954. Acrolein production by bacteria found in distillery grain mashes. Appl. Microbiol., 2 (1), 14-20.

STENHAGEN E., ABRAHAMSSON S., Mc LAFFERTY F. W., editors, 1969. Atlas of mass spectral data. Intersc. Publishers, 1, 275.

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