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Inhibition of fermentation evolution in bread doughs for aroma analyses

Pico, Joana, Bernal, José, Nozal, María Jesús, Gómez, Manuel
Flavour and fragrance journal 2017 v.32 no.6 pp. 461-469
bread dough, carbon dioxide, chromatography, ethanol, fermentation, freezing, mercuric chloride, odors, temperature, thawing, volatile compounds, yeasts
The inhibition of the residual fermentation in bread doughs, in order to avoid its evolution, could be crucial to achieve reliable qualitative aroma analyses. Several options have emerged up until now, but they present some drawbacks. In this study, a mixture of methyl octanoate and methyl decanoate (Fames) has been suggested as a non‐toxic alternative to the traditional use of mercuric chloride (HgCl₂). Rheofermentometric analyses revealed that although HgCl₂ is quicker, Fames solution is highly effective in less than 20 min. Moreover, when HgCl₂ was added to 90 min fermented dough, it exhibited an unexpected behavior with a high release of CO₂ without the generation of ethyl alcohol, which could affect the dough structure. SHS‐GC/MS analyses of ethyl alcohol and 2/3‐methyl‐1‐butanol corroborated the rheofermentometer's results, with a visible reduction in the peak areas and significant differences in the One‐way Anova between Fames doughs and blank doughs. The application of the Fames solution to SPME‐GC/MS‐QTof analyses involved a reduction in the areas regarding the blank without interferences, showing a logical progression of the volatile compounds over the fermentation time, increasing their concentration from 0 to 90 min. This progression was normally lost when the inhibitors were not added, since the yeast acted in an uncontrolled manner due to the changes of temperature during freezing, thawing or chromatographic analyses, leading to wrong aroma results.