Optimization of Apple Juice Production by Single Pass Metallic Membrane Ultrafiltration

Apple puree was treated with various amounts of commercial liquefaction enzyme (0%– 0.066%) for 2 hr at 50°C. To produce clarified juice purees were pumped through a metallic oxide membrane ultrafiltration system, consisting of 3.27 ft 2 (0.304 m 2 ) of membrane coated internally onto a l–1/4 inch (i.d.) × 10 ft (3.12 cm × 3.04 m) sintered stainless steel tubing. All enzyme treatments reduced viscosity 70–80% within 1 hr but steady state flux increased with higher concentrations of enzyme. Alcohol insoluble solids (AIS) and total pectins of the apple puree after enzyme treatment decreased as enzyme concentration increased to 0.044%. A large scale system, l–1/4 inch (i.d.) × 120 ft (3.12 cm × 36.48 m), was operated at 86% juice yield with minimal pressure drops as predicted by a mathematical model.