The content of polyphenols and the antioxidative properties were determined in soybean tempeh fermented by four strains of Rhizopus oligosporus. The highest concentration of polyphenols was observed in soybean fermented for 4 days by R. oligosporus strain NRRL 5905 (5.307 mg/g). The strength of antioxidative activity increased from the first day of fermentation to the fourth day, and on the fourth and fifth fermentation day it was near 12 times higher than in unfermented material. Isoflavone content and composition were analysed. The content of isoflavone aglycones (daidzein and genistein) increased up to the third day of fermentation. Fermentation time and the kind of used R. oligosporus strain are factors that enable creation of prohealthy quality of tempeh. Composición de isoflavonas, contenido de polifenoles y actividad antioxidante de las semillas de soja durante fermentación de tempeh RESUMEN Se determinaron el contenido de polifenoles y las propiedades antioxidantes en el tempeh de soja fermentada mediante cuatro cepas de Rhizopus oligosporus. Se observó que la concentración más alta de polifenoles fue en la soja fermentada durante cuatro días mediante cepa de R. oligosporus NRRL 5905 (5.307 mg/g). El poder de la actividad antioxidante aumentó desde el primer día de fermentación hasta el cuarto, además en el cuarto y quinto día de fermentación fue alrededor de doces veces mayor que en el material no fermentado. Se analizaron el contenido de isoflavonas y su composición. El contenido de isoflavonas aglicona (daidzeína y genisteína) aumentó hasta el tercer día de fermentación. El tiempo de fermentación y el tipo de cepa de R. oligosporus utilizada son factores que permiten la creación de tempeh de una calidad saludable.

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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.

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l-3,4-dihydroxyphenylalanine (l-DOPA) is a medically relevant compound in Parkinson’s disease therapy. Several extraction methods of l-DOPA from beans, including velvet and faba beans, have been described in the literature. However, these methods require the use of strong acids, long extraction times, or complex downstream processing, which makes the extraction of l-DOPA expensive and energy-demanding, limiting its industrial application. In addition, the stability of l-DOPA during the extraction process is critical, further complicating the extraction of adequate amounts of this amino acid. This work is the first report on a simple, rapid, greener, and robust extraction method of l-DOPA. The developed method consists of a quick homogenization step followed by a double extraction with 0.2% v/v acetic acid for 20 min and was applied to faba bean at a ratio of 1:25 with respect to the extracting solvent. This study also investigated the stability of l-DOPA during extraction and thermal treatment. The proposed method demonstrated to be robust and extraordinarily efficient for numerous cultivars of faba bean, velvet bean, and food products containing faba beans.

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