The fermentation of Jerusalem artichoke (Helianthus tuberosus L.) tubers and juices using various microorganisms: the bacterium Zymomonas mobilis, a distillery yeast Saccharomyces cerevisiae and a yeast with inulinase activity was investigated. Jerusalem artichoke carbohydrates in mashed tubers and juices were acid and enzymatic hydrolysed before fermentation by the bacterium and a distillery yeast. Although enzymatic hydrolysis with an inulinase gave less reducing sugars it was significantly more efficient in fermentation process. The ethanol yield after enzymatic hydrolysis (expressed as % theoretical yield) was 78.3-90.0% and 72.4-84.2% for the bacterium and yeasts respectively in tubers as well as 78.3-88.1% and 74.4-82.2% for the bacterium and yeasts in juices. The yield was 2.0-9.2% higher than after acid hydrolysis. The yeast with an active inulinase yielded better when juices were used for fermentation than on mashed tubers.

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