Aroma recovery by combining distillation with absorption

A new method for aroma recovery during evaporation is presented, in which, the vapour generated in an evaporator passes through an absorber where a hygroscopic solution partially absorbs water vapour. The remaining aroma rich stream is subsequently condensed. Experiments were carried out using 60% LiBr solution as hygroscopic solution and methanol, ethanol, ethyl acetate, methyl butyrate and ethyl butyrate as aroma compounds. When 20% of the feed was evaporated the aroma compounds were completely stripped from the feed, while when 10% of the feed was evaporated methanol and ethanol partially stripped from the feed. A significant amount of methanol and ethanol was absorbed by the LiBr solution (21–46%), while 3–17% of ethyl acetate, methyl butyrate and ethyl butyrate, compounds of higher relative volatility, were absorbed. The relative concentration of the aroma compounds, Ci/(Cfeed)i, in the condensate was 1.8–2.8 times higher than in the condensate obtained from comparative simple distillation experiments.