The utilization of bilimbi (Averrhoa bilimbi) and lime (Citrus aurantifolia) juices as natural acid coagulants for tofu production.

The influences of coagulation conditions on the characteristics of tofu have been investigated by many studies, with limited perspectives on the utilization of organic acid coagulants. Hence, this research aimed to study the psychochemical and functional properties of tofu coagulated by bilimbi (Averrhoa bilimbi) and lime (Citrus aurantifolia) juices. The highest tofu protein content was quantified for tofu prepared with 20% bilimbi and 5% lime juices, as much as 52.11 and 52.03% (DW), respectively. The corresponding yield was 73.46 and 69.17%. The hardness (155.98 g), gumminess (116.45 g), and chewiness (112.69 g) of treated tofu were found significantly higher than commercial tofu (p < 0.05). Total phenolic content of commercial tofu was about 370.09 μg GAE/g sample (DW). This value was significantly higher than that of treated tofu (p < 0.05). However, the antioxidant activity of the commercial tofu was lower than tofu coagulated with fruit juices. Based on SDS-PAGE analysis, protein band for 11S fraction of tofu coagulated by bilimbi and lime juices were thicker than that of commercial tofu. These small molecular weight peptides might contribute for higher antioxidant activities of tofu coagulated by bilimbi and lime juices. Conclusively, bilimbi and lime juices are potent natural acid coagulants for enhancing the physicochemical and functional properties of tofu.