Fermentation of Jerusalem artichoke by Zymomonas and Saccharomyces

Purpose - The aim of this study is to find out the appropriate fermentation conditions of Jerusalem artichoke powder (JAP) based media to obtain light beverage containing inulin. Design/methodology/approach - JAP water suspension or filtrate were used for preparation of growth media with or without enzymatic hydrolysis of inulin for fermentation by Zymomonas mobilis 113 S'' or Saccharomyces cerevisiae. Findings - If enzymatic hydrolysis of inulin was not used significantly higher amount of inulin (7.42 per cent) was unconverted by Z. mobilis than by S. cerevisiae (2.22 per cent) while the ethanol concentration was much higher (2.86 per cent) after S. cerevisiae fermentation than after Z. mobilis fermentation (1.21 per cent). Considerably more ethanol was produced by Z. mobilis during co-fermentation with Fructozyme L of JAP suspension filtrate (5.98 per cent) and suspension (4.96 per cent). Analyses of volatile components of fermentation broths showed that for production of inulin containing light beverages the best was Z. mobilis fermentation of JAP water suspension or filtrate without enzymatic treatment. FT-IR spectroscopy can be used as a quick semi-quantitative method for evaluation of inulin content. Originality/value - JAP - containing not only inulin but all tuber ingredients, was used as a media for ethanol fermentations by Z. mobilis 113 S'' or S. cerevisiae with or without hydrolysis of inulin. It was shown that Z. mobilis fermentation broths containing 7.42 per cent of inulin can be used as beverage with prebiotic-dietary fibre benefits. The taste of this product can be regulated by appropriate fermentation conditions and the concentration of fructose and ethanol.