Electro-catalytic isomerization of lactose into lactulose: The impact of the electric current, temperature and reactor configuration

A complete factorial experimental design was used to study the effect of temperature, reactor configuration and electrical current on the conversion of lactose into lactulose in an electro-activation reactor. Analysis of variance of data showed a high significance of these factors on lactose isomerization into lactulose and the formation of galactose. Optimum electro-isomerization conditions were obtained with a reactor configuration comprising a MC-40 cation exchange membrane separating the central compartment from the cathodic compartment in which the electro-isomerization reaction took place. According to the optimized conditions, lactose was converted into lactulose at a level of 30.19 ± 1.37% after 30 min of electro-activation at both 10 °C and 0 °C; galactose did not exceed 6% of the total product. The formation of galactose decreased when the electro-isomerization temperature was lowered to 0 °C. Scanning electron microscopy and X-ray analyses did not show any fouling of the membranes.