Abstract
Conventional tofu production often relies on synthetic coagulants, which may involve energy-intensive manufacturing and limited sustainability. This study investigates using natural acid coagulants, lime juice and tamarind extract, as environmentally friendly alternatives for soy milk coagulation. Coagulation was conducted at pH levels of 4.6, 4.8, 5.0, and 5.2, using souring solutions pre-adjusted to pH 2.0, 2.2, and 2.4. The highest protein curd yield was obtained with coagulation solutions at pH 2.2. Tofu samples coagulated at pH 5.0 exhibited the most favourable characteristics, including desirable colour parameters (L*, a*, b*), texture profile, water-holding capacity, and uniform microstructure as observed by scanning electron microscopy. Lime juice consistently produces tofu with better texture and moisture retention than tamarind extract. These findings highlight the potential of using natural plant-derived acids instead of synthetic agents such as glucono delta-lactone and sodium acetate. Using minimally processed, locally available ingredients aligns with sustainable food system goals and contributes to scalable, low-carbon innovations in plant-based protein production.
