Jerusalem artichoke mashed tubers were fermented using single yeasts and a bacterium as well as mixed culture of microorganisms. Kluyveromyces fragilis, a yeast with an active inulinase, was used together with either a commercial distillery yeast, Saccharomyces cerevisiae, or the bacterium Zymomonas mobilis. After batch fermentation the best ethanol concentration of 0.48 g g(-1) for the mixed population and 0.46 g g(-1) for the single population can be obtained. The theoretical yield of the mixed cultures was 2-12% higher than for the single microorganism.

The primary objective of the present study was to assess the qualitative and quantitative changes of wine polyphenols during in vitro digestion process conducted in a gastrointestinal tract model. Wines selected for these experiments were red grape, white grape and chokeberry wines. Following the stages of in vitro digestion-stomach, small and large intestine-qualitative and quantitative changes particularly in phenolic acids were monitored. Decomposition of resveratrol and chlorogenic acid, secretion of caffeic acid and formation of other derivatives characterized with high antioxidant activity were determined. As a second focus of this work the evaluation of interactions between human fecal microflora (Enterobacteriaceae, Lactobacillus, Enterococcus and Bifidobacterium) and polyphenolic compounds and their derivatives secreted during the digestion were performed.

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ObjectivesTo use the glucose–fructose oxidoreductase (GFOR) from Zymomonas mobilis and expressed in Escherichia coli for lactobionic acid production by conversion of lactose from whey.ResultsThe highest concentrations of lactobionic acid (3.2 mg ml−1) during oxidation of whey-derived lactose by E. coli was at 24 h. Introduction of GFOR gene from Z. mobilis, into E. coli improved enzyme yields compared to what is obtainable by fermentation of the donor strain. The production of lactobionic acid by E. coli was 2.6-times higher than by Z. mobilis.ConclusionsRecombinants of E. coli overexpressing the GFOR gene from Z. mobilis produced higher amount of lactobionoic acid from whey-derived lactose.

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