Abstract:

In this study, response surface methodology was used to optimize the preparation of fat substitute by
carboxymethyl substitution of rice bran dietary fiber. A Box-Behnken design involving the independent variables chosen
based on single factor experiments was used to define an experimental design matrix of reaction conditions for rice bran
dietary fiber. For the optimization of the independent variables, quadratic regression analysis was performed using Design-
Expert 8.0.6 software. The optimal parameters for the preparation of fat substitute were achieved as alkalization of rice bran
dietary fiber at 25.9 ℃ followed by 4.54 h etherification at 69 ℃ after addition of 16.27 g of chloroacetic acid per 15 g of
dietary fiber. Under these conditions, the degree of carboxymethyl substitution of rice bran dietary fiber was 1.266 8. IR
spectra confirmed the occurrence of carboxymethyl substitution in the fat substitute prepared rice bran dietary fiber.

Key words: rice bran dietary, fat substitute, preparation process, response surface methodology