Modelling of the gas–liquid partitioning of aroma compounds during wine alcoholic fermentation and prediction of aroma losses

Abstract

A model was elaborated to quantify the gas-liquid partitioning of four of the most important volatile compounds produced during winemaking fermentations, namely isobutanol, ethyl acetate, isoamyl acetate and ethyl hexanoate. Analyses of constant rate fermentations demonstrated that the partitioning was not influenced by the CO 2 production rate and was a function of only the must composition and the temperature. The parameters of the model were identified in fermentations run at different temperatures, including anisothermal conditions. The prediction of the partition coefficient (k i) by the model was very accurate for isobutanol, isoamyl acetate and ethyl hexanoate. The technological potential of the model was confirmed by using it to calculate the losses of volatiles in the gas phase during fermentation and comparing them with experimental data. Up to 70% of the produced volatile compounds were lost. The difference between observed losses and losses estimated from predicted k i values never exceeded 3%.

Combined effects of nutrients and temperature on the production of fermentative aromas by Saccharomyces cerevisiae during wine fermentation

“…It recently became possible to determine the biological production and the physical evaporation of volatile compounds by performing gas-liquid balances (Morakul et al 2011(Morakul et al , 2013. For six volatile compounds (propanol, isobutanol, isoamyl alcohol, isoamyl acetate, ethyl hexanoate and ethyl octanoate), we calculated the amount accumulated in the liquid and the amount lost in the gas.…”

“…We used a Box-Behnken design to build a model for each volatile compound describing the simple effects of these three factors as well as the interactions between these parameters (Box and Behnken 1960). We carried out gas-liquid balances for these volatile compounds (Mouret et al 2014b;Morakul et al 2013) and we used a mathematical model to predict the gas-liquid ratio of the fermentative aromas throughout the fermentation process (Morakul et al 2011). These experiments were carried out with a commercial wine yeast strain.…”

The virtual food system: Innovative models and experiential feedback in technologies for winemaking, the cereals chain, food packaging and eco-designed starter production

“…The difference between observed losses and losses estimated from predicted k i values never exceeded 3%. Finally, using this model, we calculated the total production of fermentative aromas-corresponding to the sum of liquid accumulation and gas losses (Morakul et al, 2011). Based on fermentations performed at different temperatures and initial nitrogen concentrations, we modeled the impact of these two fermentation parameters on the production yields of five fermentative aromas representative of the different chemical families.…”

“…The monitoring of alcoholic fermentation is based on measuring CO 2 release. In parallel, we developed an online GC (gas chromatography) system to monitor the synthesis of the main higher alcohols and esters (Morakul et al, 2011;Mouret, Morakul, Nicolle, Athes, & Sablayrolles, 2012). These online monitoring devices allow precise determination of the chronology of synthesis of some key compounds in alcoholic fermentation.…”

“…These kinetic data are of primary importance for a better understanding of yeast metabolism, but they also have practical interest-instantaneous CO 2 production rate, for instance, is directly proportional to the energy required for temperature control in fermentation tanks (Colombie, Malherbe, & Sablayrolles, 2007;Goelzer, Charnomordic, Colombié, Fromion, & Sablayrolles, 2009). The online data collected were used to build a model predicting the fermentation kinetics (Malherbe, Fromion, Hilgert, & Sablayrolles, 2004), gas-liquid ratio (Morakul et al, 2011) and production kinetics of five fermentative aromas (Mouret, Farines, Sablayrolles, & Trelea, 2015). These data were also used to implement an information system called ALFIS (alcoholic fermentation information system) that allows the acquisition, annotation and consultation of online and offline measurements and provides a rich digital resource for sharing data across technologies and disciplines.…”