Abstract:
Mungbean (Vigna radiate (L.) Witzek) and soybean (Glycine max L.) are the most important and famous legumes for human because there are sources of proteins as well as provides biological properties, especially antioxidant properties. Major mungbean and soybean antioxidants include isoflavones, proanthocyanidins, phenolic acids and polysaccharides. Most studies have focused on the antioxidant properties of native mungbean and soybean, however the properties of germinated mungbean and soybean have a few repots. Therefore, the study aims to compare the protein patterns between dry mature seeds and germinating seeds of the mungbean and soybean extracts as well as to investigate their antioxidant properties, which were hydrolysed with papain. The germinating seeds were evaluated at 12, 24 and 48 h after water absorption. Protein extracts of both dry mature seeds and germinating seeds were achieved by the consecutive extraction in hexane and water. Protein pattern of each extract were determined by SDS-PAGE. The results from SDS-PAGE demonstrated that no differences in amounts of protein bands extracted from dry mature seeds and germinating seeds of mungbean and the amounts of protein bands is less than protein bands from soybean. However, amounts of protein extracted from germinating soybean seeds were decreased with time. And then, these proteins were digested with papain. The antioxidant activity of mungbean and soybean extracts and soybean hydrolysate were determined using DPPH assay. Soy protein isolate from 24 h of germination were hydrolyzed by treatment with papain at 37 ๐C for 90 min that showed the highest scavenging activity against DPPH free radicals (57.42% at 2 mg/ml). Nevertheless, the protein bands of soy protein hydrolysates were not detected by 15% SDS-PAGE. These may be contained protein or peptides that have lower molecular weight than 14 kDa leading to against DPPH free radicals. As conclusion, soy protein hydrolysate with papain from 24 h of germination had the best antioxidant potency and could be used as natural antioxidant in food industry.