Tofu is becoming a popular food in Nigeria because of the various nutritional and medicinal attributes associated with soybean products. In Nigeria, tofu a coagulated product of soymilk is usually produced at household level using various types of coagulants such as calcium chloride, alum and steep water (effluent from pap produced from maize). The effect of the various types of locally used coagulants on the proximate, mineral, energy composition, digestibility (In vitro and In vivo) and biochemical response (serum enzymes and lipids) of rats fed tofu for 14days was assessed. The result of the study revealed that there was no significant difference (P > 0.05) in the tofu yield by each of the coagulants (17.5 - 18.3 %), however alum coagulation gave the highest yield, while calcium chloride gave the lowest yield. The protein (17.6 %), fat (6.2%), Mn (0.3), Mg (34.2), energy (6.6 cal/g) and In vitro multienzyme protein digestibility (75.8 - 77.6%) of steep water coagulated tofu was significantly higher (P < 0.05) than that of other coagulants. While tofu produced with alum had a significantly higher (P < 0.05) Fe (1.6), Ca (23.5), K (33.9) and Na (21.1) than the tofu produced by other coagulants. The tofu produced by calcium chloride had the highest Zn (0.6) content but the lowest energy content (5.3 cal/g) and In vitro multienzyme protein digestibility (61.6 - 63.5 %). Feeding albino rats with tofu and water ad libitum for 14days caused a decrease in the serum aspartate amino transaminase (AST), alanine amino transaminase (ALT), alkaline phosphatase (ALP), cholesterol and low-density lipoproteins when compared with the control, while there was no significant difference (P > 0.05) in the average daily feed intake, average weight gain and feed: gain ratio of the rats feed tofu. Conversely, there was a significant increase (P < 0.05) in the serum high-density lipoproteins when compared with the control. However, rats fed steep water coagulated tofu had the lowest serum
level of cholesterol and LDL followed by those fed CaCl2 and alum coagulated tofu
respectively, while those fed with calcium chloride coagulated tofu had the highest serum HDL level, and closely followed by those fed steep water coagulated tofu. It could therefore be concluded that of all the locally used coagulants in Nigeria for tofu production steep water (effluent from pap produced from maize) which is considered to be waste appears to be better for the production of tofu with high nutritional value and hypocholesterolemic effect, however it has the least acceptability, further research will be carried out on how to improve its sensory quality.