Effect of process operating conditions during potato fruit juice filtration on product properties and process performance

Potato proteins gain increasing interest, but economically viable isolation remains challenging. This study investigates the purification of proteins from potato fruit juice by cross-flow ultrafiltration using hollow fibre modules. We systematically examined pH (6, 8, 10), transmembrane pressure (1, 2 bar), and temperature (25, 35, 45 °C) to evaluate effects on filtration performance, protein composition, functionality, and sensory properties. Results revealed that pH during filtration was the most important factor affecting the resulting powders' characteristics and filtration performance. Filtrations at pH 8 showed low flux rates, and resulting powders exhibited poor solubility (38 ± 2 %) but emulsifying capacities up to 822 ± 13 mL/g. Filtrations at pH 6 showed satisfactory flux and yielded powders with low ash content. Higher transmembrane pressure increased flux across all pH levels without compromising protein properties. Temperature effects varied, but moderate temperatures generally preserved protein integrity. Gel electrophoresis showed that filtration at lower pH increased the concentration of protease inhibitors, while higher pH promoted protein aggregation. Furthermore, low pH favoured malty flavours. This study provides insights to optimise processes for improved functionality and sensory properties and underscores the potential of utilising potato fruit juice as a sustainable protein source, contributing to the valorisation of agricultural by-products.