Acidification in Distillation Technology

Abstract

The quality of distillates depends on the biochemical composition of the raw material, the operating parameters of the wort production and fermentation, and the methods and modes of distillation. The active acidity of the medium (pH) can affect wort fermentation and distillation processes. The research objective was to study the effect of the active acidity of bakery waste wort on fermentation and distillation processes. 
 The study featured fermented wort samples from wheat bread, a mix of wheat and rye-wheat bread, and distillate fractions obtained by a single fractionated distillation of fermented wort. The distillation occurred in laboratory conditions in a direct distillation unit (Kothe Destillationstechnik, Germany) with a 10 dm3 cube. The effect of the acidification degree of saccharified wort on the fermentation efficiency was determined by the strength of the fermented wort. The composition of volatile components in the distillates was defined by gas chromatography in a Thermo Trace GC Ultra chromatograph (Thermo, USA). 
 When the pH of saccharified wort fell from 5.5 to 4.5–3.5, the synthesis of higher alcohols and ethers of higher fatty acids decreased during fermentation, while the acetone mass concentration increased. The acidification of fermented wort to pH = 3.5–3.0 at the distillation stage had a positive effect on the distillates from recyclable baking waste. This technique increased the yield of the middle fraction (distillate) by reducing the loss of absolute alcohol with the head and tail fractions. The concentration of acetaldehyde and ethyl acetate in the middle fraction decreased by 1.5 times while the content of enanthic ether components increased by more than 75%. As a result, the sensory profile increased by 0.4–0.5 points. The distillates from the mix of wheat and rye-wheat bread were superior to distillates from wheat bread. The statistical analysis provided the following criteria for a qualitative assessment of the distillates from recyclable baking waste: the mass concentration of acetaldehyde and the ratio of alcohols C5 to the sum of alcohols C3 and C4.
 Pre-fermentation oxidation of saccharified wort proved impractical for bakery waste recycling, whereas acidification of fermented wort before distillation increased the distillate yield and improved its sensory profile.