Introduction. The aim of this work was to develop a list ofsuitable sensory attributes and to perform sensory quality assessment of an unprocessedpeach juice and a peach juice clarified by enzymatic treatment followed by membraneprocesses, using the attributes chosen by the trained panel. Materials andmethods. A panel of assessors was selected and trained following the quantitativedescriptive analysis methodology. A descriptive terminology with eight descriptors wassuccessfully developed. Results and discussion. The sensory analysis showedthat the juices were effectively clarified. Although the clarification by microfiltrationin a bench-scale unit did not change juice taste attributes, the characteristic color andaroma of peach juice were also removed. The scale-up of the membrane clarification processaffected all the sensory characteristics of the clarified juice, even taste. Theunpleasant cooked fruit taste and aroma could be reduced by juice clarification byenzymatic and membrane processes. The kind of membrane, membrane geometry andtransmembrane pressure used in the membrane clarification did not significantly affect thejuice sensory characteristics.

Introduction. Ultrafiltration (UF) is a single-unitoperation for the clarification and fining of fruit juices. Thepurpose of the UF is to remove suspended solids as well as haze-inducingand turbidity-causing substances to obtain a clear juice duringstorage. Specifically, the polymerization of phenolic compoundsand their interaction with other components (e.g.,proteins) could cause a haze complex and turbidity in fruit juices,which can foul the ultrafiltration membrane. Materials and methods.Fresh pomegranate juice was clarified by the ultrafiltration processon a laboratory scale. In experimental tests performed according tothe total recycle and the batch concentration mode, the effectsof transmembrane pressure (TMP) and enzyme pre-treatment on permeationflux and quality of juice were studied. Results. With the totalrecycle mode, the effect of TMP on the color and clarity of clarifiedpomegranate juice was significant. The initial color of the rawpomegranate juice was reduced from 74% to 33% and the clarity decreasedfrom 77% to 42% by UF when the TMP increased from (1 to 3.6) bar.Total phenolic rejection decreased from 45% to 21% when the TMProse from (1 to 2) bar and remained constant above this value. Withthe batch concentration mode at TMP = 2 bar and velocity 1 m·s–1,the enzymatic treatment (5 U·mL–1, 300 min, T = 20 °C)of pomegranate juice provided the highest permeate flux, a decreasein total phenolics of 50% and an increased clarity of 30%. Foulingof the UF membrane during pomegranate juice processing is mainly dueto the retention of polyphenols and/or proteins; thus, several blocking mechanismswere studied, using a recently developed membrane-fouling model.Analysis revealed that the membrane separation process was controlledby the gel layer mechanism of raw pomegranate juice and complete poreblocking mechanism with enzymatic pre-treatment.