Physical, Chemical and Sensory Qualities of Roselle Water Extract-coagulated Tofu Compared with Tofu from Two Natural Coagulants

Abstract

Roselle calyces (Hibiscus sabdariffa) aqueous extracts were used in coagulating soymilk at four different concentrations (2.5%, 5%, 10% and 20%). The physical, chemical and sensory qualities of the tofu preparations were compared with fermented maize liquor and Calotropis procera extract coagulated tofus. pH of roselle extracts was acidic in nature (2.01 – 3.74) which was attributed to the ability to coagulate soy proteins. pH, titratable acidity of the roselle coagulated tofus ranged from 5.32 – 6.26 and 0.16 – 0.43% respectively and the yield and protein content ranged from 87.3 – 95.9 g and 42.6 – 46.3 g/100 g respectively. The yield of roselle coagulated tofu increased with increase in concentration of the roselle extracts. Roselle extract when utilized at 2.5% concentration will yield tofu that is acceptable and comparable to tofu coagulated with fermented maize steep water in terms of appearance, flavour and overall acceptability at p > 0.05. Roselle extract at 5% and 10% also yielded tofus that were acceptable in terms of all of the attributes tested.