Pengaruh konsentrasi koagulan CaSO4.2H2O dan suhu terhadap proses koagulasi protein dan tekstur curd

Abstract

Texture is an important aspect to determine consumer preferences for products based curd, one of them is tofu. Differences in texture of are influenced by the parameters of the coagulation process which consists of coagulant concentration and coagulation temperature. Effect of differences in coagulation parameters was represented by the data of whey transmittance, whey protein content, pH value of whey, curd protein profiles, moisture content and total solids of curd, and curd texture (objectively by TPA devices). This study used CaSO4.2H2O as a coagulant for soybean milk with the concentration of 0.015 N (A), 0.030 N (B), and 0.045 N (C). Soy milk was coagulated at the temperature of 60 and 80°C. Coagulation produced curd tofu and whey. The data suggest that whey C had the highest transmittance [23.52% (60°C) and 19.30% (80°C)], whey protein B had the lowest [0.448 mg/mL (80°C) and 0.390 mg/mL (60°C )], while the whey pH values were not significantly different in the range of 5.72 to 5.90. The curd C had the highest moisture content (wet basis) [20.63% (80°C) and 18.69% (60°C)] and the highest total solids/yields (raw material basis) [40.88% (60°C) and 37.75% (80°)]. The function f(x) = y = 2.896x + 1358 was obtained to correlate the curd texture by objective measurement (x) and the sensory evaluation (y). Curd C (80°C) had the highest hardness 2.474 (slightly hard) while the curd A (60°C) had the lowest hardness 1.164 (soft). Meanwhile, the curd protein profiles consists of 7S globulin (β-conglycinin) and 11S globulin (glycinin) protein subunits. The 7S protein consists of subunits α, α’, and β, while the 7S protein consists of the acid subunits (A1, A2, A4, A6) and the base subunit. Percent of 11S subunits in the curd increased with increasing concentration of coagulant in all the coagulation temperature. The percent of 7S subunits indicated otherwise, as well as its components, α+α’ and β. Overall, subunits of proteins that have an influence on the texture are the A1 subunit and the base subunit of the 11S proteins with the highest Pearson correlation on the curd cohesiveness.