Changes in organic acid contents during mead wort fermentation

Abstract

Organic acids contained in honey influence the fermentation rate and frequently cause mead fermentation to halt. The purpose of this study was to determine the changes that occur in a group of selected organic acids during the fermentation of mead worts and their impact on the process. Mead worts (1:2 and 1:3 (honey:water)) were fermented using Saccharomyces cerevisiae yeast of the Johannisberg-Riesling breed (ŁOCK 105). The worts were supplemented with diammonium hydrogen phosphate (0.4 g/l) and citric acid (0.25 g/l). During fermentation, the contents of selected carboxylic acids were determined using gas chromatography. Mead worts contain relatively high amounts of medium-chain fatty acids, which are believed to inhibit fermentation. The dominant compounds of this group are decanoic (42 mg/l), dodecanoic (31 mg/l) and octanoic (26 mg/l) acids. The experiments demonstrated that during the early days of fermentation, the main acids to form are the acetic and succinic acids, which reduce the wort pH, while the content of fatty acids drops by 70–80%. During fermentation, the amounts of the formic, hexadecanoic and octadecanoic acids also fall.