Determination of Optimised Malting Conditions for the Enrichment of Rutin, Vitexin and Orientin in Common Buckwheat (Fagopyrum esculentum Moench)

M. Krahl^1,3, W. Back1, M. Zarnkow¹ and S. Kreisz²
¹ Technische Universität München, Lehrstuhl für Technologie der Brauerei I, Weihenstephaner Steig 20, 85354 Freising-Weihenstephan, Germany.
² Novozymes A/S, Bagsværd, Denmark.
³ Corresponding author. E-mail: Moritz.Krahl@wzw.tum.de

J. Inst. Brew. 114(4), 294–299, 2008 | VIEW ARTICLE

ABSTRACT
Buckwheat (Fagopyrum esculentumMoench) is known to be an excellent source of polyphenols. In this study, common dehulled buckwheat was malted and the changes in the flavonoid content of the kernels were measured. In order to determine optimum malting conditions for the enrichment of rutin (quercetin-3-rutinoside), vitexin (apigenin-8-glucosid) and orientin (luteolin-8-glucosid), malting parameters were varied according to a statistical model. Using this central composite design helped to determine optimum parameters. Numerical optimised malting parameters were a germination temperature of 22°C and a germination time of 7 days and the resulting moisture content in the kernels was 61%. Using these parameters the calculated rutin content increased from 13.8 mg/100 g (d.w.b. [dry weight basis]) to 105 mg/100 g (d.w.b.). Vitexin and orientin could not be found in the unmalted kernels and concentrations in malt reached 87 g/100 g (d.w.b.) for orientin and 96 mg/100 g (d.w.b.) for vitexin.

Key words:
Buckwheat, malting, orientin, polyphenols, rutin, vitexin.