Nonthermal concentration of skimmed goat milk by forward osmosis: The insights into process performance and product quality

Abstract

Nonthermal processing technologies have been gained increasing attention in the dairy industry recently. In this study, the feasibility and effects of forward osmosis (FO) process as a nonthermal technique in the concentration of skimmed goat milk (SGM) were assessed and compared with thermal evaporation. The effects of operational conditions including membrane orientation, crossflow rate, concentration of draw solution (DS), and temperature of feed solution (FS) on process performance and concentration efficiency were explored. The total solids content of raw SGM can be increased from 9.07% to 18.78% through a single-stage FO process to reach a concentration factor of 2.0. Membrane fouling could be mitigated by improving the crossflow rate. Osmotic backwash proved to be the most effective cleaning approach to restore membrane performance with a flux recovery rate reaching 100%. The nonthermal FO process showed the superior performance to traditional thermal evaporation in retaining the natural characteristics of milk. Economic and energy evaluation indicated that such FO process with a pilot scale could be promising in the milk concentration at a low cost of $2.69/m3 with a low energy consumption of 4.80 kWh/m3. It could be an effective and promising concentration approach for producing concentrated milk with promoted quality.