Antioxidant Capacity and Amino Acid Profiles of Egg Tofu

Tofu contains high quality protein source and antioxidant which could reduce risk of cancer. This research aims to determine the effect of soymilk and egg ratios on the antioxidant capacity, daidzein and genistein content and amino acid profiles of egg tofu. Egg tofu was prepared using soymilk and fresh egg in ratios of 1:1, 2:1, 3:1 and 4:1. Glucono-Delta-Lactone (GDL) was added in the egg tofu to act as a coagulating agent. Increased of soymilk at all ratios had significantly (p<0.05) increased in Ferric-Reducing Antioxidant Power (FRAP), daidzein and genistein content of egg tofu. Conversely, decreased in soymilk ratio had significantly (p<0.05) increased the radical scavenging activities of the 2,2-Azino-Bis 3-ethylbenzothiazoline-6-Sulfonic acid (ABTS) and 2,2-Diphenyl-2-Picrylhydrazyl (DPPH) in egg tofu. Increased of soymilk ratio up to 3:1 caused decreased in amino acid methionine (met) and cystein (cys) significantly (p<0.05). A significant (p<0.01) and a positive correlation was observed between Total Phenolic Content (TPC) and FRAP (r = 0.93). However, there was a negative (p<0.01) correlation between TPC and DPPH (r = -0.83). The antioxidant capacity of egg tofu in DPPH assay showed a positive and significant (p<0.01) correlation with cysteine, methionine and tryptophan with r value of 0.92, 0.93 and 0.96 respectively. Higher content of egg in egg tofu had contributed to the increased of antioxidant capacity as indicated in DPPH assay and ABTS assay as well as amino acid methionine and cysteine.