Browsing by Person "Reber, Oliver"

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Effect of partial condensation (dephlegmation) in fruit brandy distillation equipment on the composition of apple brandies
(2025) Yagishita, Manami; Reber, Oliver; Alter, Daniela; Kölling, Ralf; Einfalt, Daniel; Chinnici, Fabio
Fruit brandy equipment commonly uses partial condensation (dephlegmation) to generate reflux in the distillation column. Here, we examined the effect of dephlegmation on the composition of fruit brandies in both lab-scale and large-scale settings. In lab-scale experiments, the dephlegmator led to a pronounced enrichment of ethanol in the distillate due to preferred condensation of water, while the concentration of flavor compounds was differentially affected. Some compounds were enriched in the distillate, some were depleted, and some were unaffected by dephlegmation compared with the control without a dephlegmator. Large-scale fruit brandy equipment relying exclusively on dephlegmation was compared as standard with an enrichment section containing three trays. In the equipment relying on dephlegmation, tail components such as fusel alcohols were less well separated from the middle run, which led to a reduced yield of clean spirit in the middle run. In triangle tests, the spirits from the two devices could be clearly differentiated, but there was no clear preference for one spirit or the other. This study provides for the first time detailed data on the influence of dephlegmators on the behavior of flavor compounds during fruit brandy distillation.
Optimizing aroma compound fractionation in pear brandy distillation by controlling their relative volatility
(2025) Yagishita, Manami; Reber, Oliver; Alter, Daniela; Kölling, Ralf; Einfalt, Daniel
This study aims at improving the fractionation of key odor compounds in pear brandies by controlling their relative volatility through novel fractionation strategies. Two approaches were tested: one using a high cooling water flow rate at the dephlegmator with a slow distillate flow and another employing a distillation column with 12 trays. Both effectively elevated ethanol concentration on the top tray, altering the relative volatility of compounds in the liquid phase and influencing the final product composition. The behavior of compounds closely aligned with their relative volatility data. Elevated ethanol concentrations reduced the relative volatility of higher alcohols, delaying their release from the column and producing sharper peaks compared to the broader profiles in the control distillation. This enabled the effective separation of beta-damascenone and ethyl (E,Z)-2,4-decadienoate (pear ester) from higher alcohols, creating an aroma-rich tails fraction enriched with these desirable compounds. Mixing this tails fraction with the hearts fraction produced a blend that was significantly preferred in sensory evaluations over the standard hearts fraction. These findings highlight the importance of tailoring ethanol profiles in the distillation apparatus to optimize compound separation and enhance the quality of pear brandies.