Method for preparing melanoidin with antioxidant activity

The invention discloses a method for preparing melanoidin with antioxidant activity, belonging to functional food processing technology. The method comprises the steps of performing ultrasonic-assisted ethanol extraction on degreased soybean paste slag cake, then centrifuging to obtain supernate, concentrating the supernate, dividing the concentrated supernate into two parts, and performing ultrafiltration and macroporous adsorption resin processing on the two parts respectively to obtain a melanoidin extracting solution with three molecular weight sections (smaller than 5000Da, 5000-10000Da, and more than 10000Da), wherein through comparison, the melanoidin purified by the macroporous adsorption resin has the antioxidant activity significantly superior to that of the melanoidin obtained through ultrafiltration purification, and the antioxidant activity of the melanoidin with the molecular weight of 5000-10000Da is the strongest; concentrating and drying the melanoidin extracting solution of 5000-10000Da to obtain the melanoidin with the antioxidant activity, wherein the scavenging capacity of the OH (hydroxyl) free radical and DPPH (1,1 diphenyl-2-trinitrobenzene hydrazine) free radical of the melanoidin is equivalent to that of Vc. The melanoidin can be used to develop functional food with strong antioxidant activity.