Isolation of an in vitro and ex vivo antiradical melanoidin from roasted barley

The antiradical properties of water-soluble components of both natural and roasted barley were
determined in vitro, by means of DPPH¥ assay and the linoleic acid-â-carotene system, and ex vivo,
in rat liver hepatocyte microsomes against lipid peroxidation induced by CCl4. The results show the
occurrence in natural barley of weak antioxidant components. These are able to react against low
reactive peroxyl radicals, but offer little protection against stable DPPH radicals deriving from
peroxidation in microsomal lipids. Conversely, roasted barley yielded strong antioxidant components
that are able to efficiently scavenge free radicals in any system used. The results show that the
barley grain roasting process induces the formation of soluble Maillard reaction products with powerful
antiradical activity. From roasted barley solution (barley coffee) was isolated a brown high molecular
mass melanoidinic component, resistant to acidic hydrolysis, that is responsible for most of the barley
coffee antioxidant activity in the biosystem