Clarification and sterilization of raw depectinized apple juice by ceramic ultrafiltration membranes

Abstract

Raw depectinized apple juice was clarified and sterilized in a cross-flow pilot scale ultrafiltration system using ceramic tubular membranes (MEMBRALOX  , Pall) with mean pore size of 100 nm. The permeate flux significantly decreased with time until a steady-state was established. An increase in filtration pressure increased the permeate flux while there is an optimum pressure (about 0.85 bar) above which the increase of pressure does not increase the flux significantly. The higher the cross-flow velocity was, the higher was the transmembrane flux. When the operating temperature increased, the permeation rate increased subsequently. Analytical measurement showed that suspended solids and turbidity could almost be removed by the ceramic ultrafiltration membrane, but pH, acidity, sugar and soluble solid content of the juices showed no significant change. The bacteria challenge tests with Micrococcus flavus showed that the logarithm value of the bacteria reduction rate came up to above 9 in the cross-flow tubular ceramic system. When the permeate was collected in sterile bottles in a laminar flow shell and kept at 4 • C, 8 • C, 25 • C and 35 • C, for 28 days, the apple juice experienced minimal changes in physicochemical properties at lower temperatures of 4 • C, or 8 • C.

Process optimisation of the bitter gourd (Momordica charantia) concentrated juice preparation for a freeze‐dried powder

“…However, when operating pressure was more than 0.15 Mpa, the slope of permeate flux curve became flat. Similar results were observed by Li et al. (2006) in clarification and sterilization of apple juice with a cross‐flow pilot scale UF system using ceramic tubular membranes.…”

“…After a rapid decrease at the beginning, the permeate flux decreased slowly. The permeate flux was up to 137 L per (h.m 2 ) at the starting period, but it was still kept at 110 L per (h.m 2 ) when the operating time was at 160 min, indicating that the ceramic film had a good productivity under the lower operating pressure, which is similar to the observation by Li et al. (2006) in clarification of apple juice with a cross‐flow UF system using ceramic membranes.…”

Effect of previous enzymatic recirculation treatment through a tubular ceramic membrane on ultrafiltration of model solution and apple juice

“…This solution circulates tangentially to the surface of the membrane channels. The feed solution (1000 mL) in a constant temperature recirculating bath (50°C) (Li et al, 2006) was introduced into the system from a feed tank. During circulation, the liquid was separated into two phases: one part that passed through the membranes: the permeate (or filtrate) from which was collected in a tank and measured with digital balance (Ibarz and Lozano, 1992) in grams, and the other that does not pass through the membranes: the retentate (or concentrate) of which circulates by the force of the peristaltic pump (Prominent Ò , Heidelberg, Germany).…”

Heat resistance and the effects of continuous pasteurization on the inactivation ofByssochlamys fulvaascospores in clarified apple juice

“…The objective of this procedure was to allow for the recovery of fungal spores injured by the heating process of the juice, increasing the probability of detecting survivors (one spore per 100 ml -detection limit of the heatresistant mould count method for one spore per 16 l juice of bottle incubation). The fluid flow regime was determined from the thermophysical properties of the CAJ that affected its flow (q = 105 kg (m 3 ) )1 ); l = 1AE4 · 10 )3 Pa s; Constenla et al 1989;Li et al 2006) and the internal diameters of the tubes in each section of the unit. As the Reynold's number (Re) was in the transition zone (c. 2400), it was assumed, for questions of safety, that the fluid flowed with a laminar regime, such that the fastest particle was submitted to the minimum pasteurization condition (Toledo 1991).…”