Structure and functional characterization of melanoidins from crystal malt.

In this work, the extraction method of melanoidins in crystallized malt was optimized by response surface and the relationship between structure and functional activity of different molecular weight (MW) components obtained by ultrafiltration was preliminarily discussed. The results showed the optimal extraction conditions of melanoidins in crystal malt including the ethanol volume fraction of 70%, the liquid–solid ratio of 30:1 and the extraction time of 5 h. All components exhibited similar microstructure, including the same network structure, functional group composition, phase composition and electronegative. The differences were that with the increase of MW, the microstructure was more cross-linked, the number of chromophores was more and the electronegativity was higher. Different structures of the components led to significant differences in the functional activity, including the colority, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activities, total reducing power, 2, 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activities and the angiotensin converting enzyme (anti-ACE) activity. The results expand the knowledge of melanoidins from crystalline malt, which will be conducive to elucidate the relationship between structure and function. [ABSTRACT FROM AUTHOR]