Sensory and physio-chemical properties of membrane filtered apple juices

Shelf-stable apple juices were prepared using two ceramic and four polymeric tubular membranes of varying pore sizes and evaluated using color matching and triangle tests. Juices from 9 kDa and 20 kDa membranes were different in color and aroma/flavor from the other membranes, the characteristics of which did not differ from each other. A full sensory profile was obtained for experimental juices produced using a 0.02 mu m ceramic membrane and from commercial pasteurized apple juice. Experimental juices were prepared from fresh and stored apples with and without ascorbic acid. Twelve judges evaluated color; cooked/caramelized, appley, fruity and green aromas and seven flavor attributes (cooked/caramelized, appley, fruity, green, sweet, sour, astringence). Analysis of variance and principal component analysis revealed that membrane filtered juices lacked the cooked/caramelized aroma and had a green flavor compared with the commercial apple juice. Membrane filtered juices prepared from freshly harvested apples had less appley and fruity aroma and flavor, but were more sour and astringent than juices prepared from stored apples. Ascorbic acid treatment significantly reduced the yellow color and increased the astringence of juices.