Raziskave vsebnosti flavonoidov, taninov ... / Starting points for the study of the effects of flavonoids, tannins and crude proteins in grain fractions of common buckwheat (Fagopyrum esculentum Moench) and Tartary buckwheat (Fagopyrum tataricum Gaertn.)

Abstract

Izvleček

Raziskovali smo vzorce zrnja oz. moke navadne ajde (F. esculentum Moench) in tatarske ajde (F. tataricum Gaertn.). Preučevali smo tri vzorce tatarske ajde iz Luksemburga ter dva vzorca navadne ajde iz Slovenije (cv. ´Darjo´in ´Sivo´). Z mletjem in presejanjem navadne ajde ´Darja´ in tatarske ajde smo pripravili štiri frakcije z različnimi granulacijami ter iz njihpripravili testo oziroma luščine in otrobe navlažili z vodo. S spektrofotometričnimi analizami smo spremljali deleže posameznih frakcij, vsebnost beljakovin in pepela v vseh mlevskih frakcijah in presejanih podfrakcijah ter koncentracijo flavonoidov in taninov v vzorcih moke in testa (liofilizirani vzorci). Tatarska ajda ima bistveno višjo vsebnost flavonoidov kot navadna ajda (tudi več kot 100-krat več v moki). Najvišja vsebnost flavonoidov je v mlevskih frakcijah tatarske ajde z granulacijo nad 100 μm do vključno 1000 μm in sicer 3,5–4,5 % flavonoidov/SS. Tako tatarska kot navadna ajda v vseh mlevskih frakcijah vsebujeta tanine; najvišja koncentracija taninov (0,8 %/SS pri navadni ajdi in 1,3 %/SS pri tatarski ajdi) je v mlevski frakciji z granulacijo nad 236 μm do vključno 1000 μm. Flavonoidi, pa tudi tanini, se po mlevskih frakcijah (z različno granulacijo) različno razporejeni. Razporeditev med mlevskimi frakcijami ni enaka pri tatarski in navadni ajdi. Različni vzorci tatarske ajde se med seboj razlikujejo po vsebnosti polifenolnih spojin, posebej velike so razlike v vsebnosti flavonoidov, manjše pa so razlike v koncentracijah taninov. 

Ključne besede: ajda, proteini, flavonoidi, tanini, razporeditev 

Abstract

Samples of Tartary buckwheat (F. tataricum Gaertn., domestic cv. from Luxemburg), and two samples of common buckwheat (F. esculentum Moench, cvs. ´Darja´ and ´Siva´) were tested for their concentrations of phenolic substances, and concentration levels of protein, ash, total flavonoids (spectrophotometric, with AlCl3), tannins (with vanillin-HCl method). Samples were milled with laboratory mills and sifted using laboratory planar sieves. Flavonoids and tannins are unevenly distributed among milling fractions. Their distribution was different in Tartary buckwheat, in comparison to common buckwheat. From the point of view of functional food, milling fractions with particle size over 100 μm, up to 1000 μm (the yield of latter is after milling about 30 %) is of primary interest, as they have the highest concentration of flavonoids. A positive linear correlation was established between the content of proteins and minerals in different milling fractions. Tartary buckwheat contained significantly more flavonoids in comparison to common buckwheat (up to 100-times more total flavonoids). In the investigated samples, the highest concentration of flavonoids (3.5–4.5 % flavonoids, dmb.) was in the Tartary buckwheat milling fractions of sample T1 (granulation above 100 μm, up to including 1000 μm). The husk fraction of Tartary buckwheat had a low concentration of flavonoids, but more interesting was the husk fraction of common buckwheat, which evidenced a higher concentration of flavonoids in comparison to other milling fractions of common buckwheat. 

Key words: buckwheat, proteins, flavonoids, tannins, distribution