EFFECTS OF TYPES AND CONCENTRATIONS OF COAGULANT ON THE ANTIOXIDANTS OF PURPLE TOFU

Abstract

The objective of the study was to evaluate the effects of coagulants, including nigari, citric acid, and calcium sulfate, on coagulant concentrations (0.1%, 0.2%, 0.3%, 0.4% w/v). The evaluation was based on changes in antioxidant content such as total polyphenols (TPC), total flavonoids (TFC), and anthocyanin content. These changes demonstrated the ability to neutralize DPPH and ABTS free radicals with half inhibition capacity (IC50). The results showed that coagulation with nigari at a concentration of 0.2% (w/v) produced tofu supplemented with purple sweet potato with the highest antioxidant capacity, including TPC (47.13 mg GAE/g dw), TFC (13.73 mg QE/g dw), anthocyanin content (311.25 µg/g dw), DPPH free radical scavenging ability (74.85 µmol TE/g dw) and ABTS (102.96 µmol TEAC/g dw), with an IC50 value (7.48 mg/ml).