Membrane fouling mechanisms and permeate flux decline model in soy sauce microfiltration

Microfiltration (MF) is a promising technology in soy sauce clarification. However, serious membrane fouling always lead to high operation costs, which restrict the application of the microfiltration technology. In this study, a spiral wound polyvinylidene fluoride membrane was used to explore the influences of processing conditions on membrane fouling mechanisms under total recycle mode in pilot scale. Results showed that the permeate soy sauce nearly preserved the whole nutrition and flavor substances, and the turbidity values remained below 2 NTU during 6 months' room temperature storage. Cake layer and concentration polarization resistance dominated the fouling resistances, which were influenced by operating conditions significantly. A semi-empirical mathematical model was further proposed to quantitatively describe these influences. The predicted values of the model were consistent with the experimental data with a deviation about 10%. This is helpful for the application of membrane technology in soy sauce clarification process. Practical applicationsMicrofiltration provides soy sauce products with superior clarity. Meanwhile, it keeps most of the flavor and nutrition substances. The aim of this study is to clarify the membrane fouling mechanisms and reducing the membrane fouling in soy sauce clarification. The fouling resistance was analyzed to investigate the influences on membrane fouling under different operating parameters. The novel proposed mathematical model could be used to predict the permeate flux and describe the filtration status under different operating parameters. This study provides a theoretical basis in reducing the membrane fouling for process optimization in soy sauce microfiltration clarification. Moreover, it helps to improve the product quality and production efficiency in soy sauce microfiltration industrial application.