Potentials of Sodom apple (Calotropis procera) extract as a coagulant to substitute Alum in soy cheese production in Ghana

Abstract

This study was conducted to determine the potentials of Sodom apple (Calotropis procera) extract as a sole coagulant of soymilk during soy cheese production. Four alum concentrations were prepared and used as control treatments: A5 (0.5 % conc.), A10 (1.0 % conc.), A15 (1.5 % conc.) and A20 (2.0 % conc.). Four strengths of Calotropis procera extracts (CPE) (C15, C20, C25 and C30) were obtained from 15 g, 20 g, 25 g and 30 g respectively of the fresh plant. Each of the concentrations of alum and CPE was used as a sole coagulating agent of soy milk and the effects on clotting time, product yield, whey volume and organoleptic properties of the curd were assessed. The average milk clotting time, curd yield, and whey volume were significantly (P < 0.05) influenced by the type and concentration of coagulant used to achieve curdling. The average clotting time, curd yield, and whey volume were in the ranges of (6.0 - 31 minutes), (120.2 – 207.8 g/l), and (495.0 – 785.0 ml/l) respectively. Treatments A20 and C30 recorded the shortest clotting times of 6.0 and 9.0 minutes respectively whereas treatment A5 had the longest clotting time (31.0 min). The curd yields were high in treatments A10 (207.8 g/l), C30 (191.2 g/l) and C25 (183.9 g/l) whereas A20 recorded the least curd yield (120.2 g/l). In the alum treatments, positive correlation (r = 0.585) was observed between soy milk clotting time and soy curd yield. On the contrary, there was strong negative correlation (r = - 0.803) between clotting time and curd yield when CPE were used as coagulants. The different concentrations of alum and C. procera added to soy milk had significant (P < 0.05) effects on the organoleptic properties (taste, colour, texture and overall acceptability) of the soy cheese produced. The soy cheese flavour did not vary significantly (P > 0.05) among the treatments. Generally, it was observed that the 25g CPE can be used to substitute for alum in soy curd formulation