Protein Recovery from Potato Processing Effluent Stream Using Ultrafiltration Membrane

Abstract

Wastewater effluent from potato processing industry is highly polluted and requires costly treatment systems before being discharged. However, this stream is rich in valuable contents such as starch, protein and vitamins that can reduce the expenses for the plant and modify waste treatment, in case of recovery. Most of the potato processing companies use the simple hydro-cyclone systems to recover starch from the waste. However, the protein is still being wasted in many processing plants. There has been some approaches to recover potato protein from potato fruit juice (PFJ) which is the stream from potato starch manufacturing. Previous works have shown that the traditional methods for protein recovery, like concentration, precipitation and heat coagulation have not been successful in recovering high yield of high quality and functionality protein. The produced protein using these methods also cannot be used for human food due to denaturation, poor quality and functionality. Heat precipitation also resulted in low re-solubility of protein which makes the product to be useable for animal feed, although the method is being commercially used. Similarly, ion-exchange on carboxymethyl cellulose resulted in high yield of protein recovery with insolubility and acidic pH. Ion-exchange using Expanded Bed Adsorption (EBA) was successful to recover high yield of high quality and un-denatured potato protein but it is complex and expensive. Membrane ultrafiltration (UF) technology also achieved high yield of potato protein recovery as reported in the literature but it has not been commercialised due to membrane fouling issues while the technology has been widely used in food industry. In the current research work, potato protein recovery from potato processing water (PPW), which is the stream from chips production plant, was approached by using UF membrane with the focus on fouling minimization through pre-treatment strategies. The quality and functionality of the recovered protein was the assessed and compared to commercially available potato and pea protein. Process and product improvement through the study of dead-end and cross flow configuration and increasing the purity of the recovered protein was investigated by addition of diafiltration prior to scale up to pilot rig. A pilot scale rig was designed and built based on the experimental parameters to validate the process for commercial production.