Effect of processing variables on the quality of calcium - fortified soy milk (Thai)

Abstract

The objectives of the study are to investigate the factors related to processing calcium fortified soy milk
and their effects on the chemical and physical properties, to determine optimum processing conditions. The
first study was performed to screen important factors affecting chemical and physical properties of calcium
fortified soy milk. The type of calcium, type of stabilizing agent, sequestrant content and soybean to water
ratio were studied. Results revealed that dicalcium phosphate content (A), sequestrants content (B) and 
soybean to water ratio (C) showed significant effects on the chemical and physical properties. A mathematical
model describing relationship between calcium content, overall liking and factor A, B and C were = 171.087
+ 62.612A - 9.540C - 4.738A2- 36.695C2 and 55.034 - 7.705A - 4.309B + 3.895C - 3.105A2-4.372B2- 8.821C2
respectively. Five formula conditions of calcium fortified soy milk were 2% dicalcium
phosphate and 1:4.5 soybean to water ratio, provided the highest calcium content (237.92 mg/100 ml of
soy milk) and the highest liking score (58.91). The chemical and physical properties of fortified soy milk
were as follows: protein content (4.32%), pH (7.94), viscosity (22.36 cps.), lightness (L*, 77.50),
redness (a*, -0.13), yellowness (b*, 15.66) and whiteness index (72.59). In addition, consumer
acceptance tests showed that the calcium fortified soy milk with optimum conditions obtained higher liking
scores of color, flavor, taste, texture and overall liking score (p< 0.05) than those of the commercial soy milk
products.