Clarification of Apple Juice by Hollow Fiber Ultrafiltration: Fluxes and Retention of Odor‐Active Volatiles

Fresh apple juice was clarified in a pilot scale ultrafiltration (UF) unit, with membranes made of polysulfone and polyamide and plate and frame and vacuum drum filters. Flux of apple juice (L/m 2 hr) vs UF transmembrane pressure data showed an optimum at a pressure of about 140 kPa. Retention of odor‐active volatiles was highest in plate and frame filtered apple juice and lowest in vacuum drum filtered juice; the retention of odor‐active volatiles in UF juice was intermediate to the two traditional filtration methods. Retention of odor‐active volatiles in the permeate of a polyamide membrane was higher than that of a polysulfone membrane.