Ultra high pressure homogenized soy flour for tofu making

Abstract

Using whole soybean for tofu making can effectively reduce the okara waste, increase the utilization of raw material, and lower the production cost. However, the fiber in whole soybean would alter the protein concentration in soymilk and might weaken the structure of tofu. In the current study, UHPH was used for reducing the particle size of soy flour, non-thermally denaturing the soy proteins, and making a high quality tofu. Two soy flour suspension concentrations (15% and 20%) were treated by UHPH with four combinations of pressures and cycles. Glucono-δ-lactone (GDL) was used as coagulant for tofu making. Soy flour suspensions heated at 95 °C for 10 min were used as the control. The result showed that the UHPH treated soy flour suspension had a smaller and more uniform particle size than in the control. Under appropriate pressure and cycles the hardness, gumminess and chewiness of tofu made from soy flour treated with UHPH was similar to the control tofu. The tofu made from 20% soy flour suspension with 150 MPa UHPH for 3 cycles had the lowest expressible water and syneresis. Control tofu showed a particles inlaid, incomplete honeycomb-like network, whereas UHPH tofu had a regular, continuous honeycomb-like structure. The above results indicated that UHPH reduced the particle size of soy flour, denatured the soy proteins, and could produce a favorable tofu with high level of functional components such as fiber.