Changes in Physicochemical Profiles and Quality of Apple Juice Treated by Ultrafiltration and During Its Storage

Effects of various factors, such as membrane materials, molecular weight cutoff, transmembrane pressure (TMP), and cross flow rate (CFR) on flux and physicochemical properties of apple juice during ultrafiltration and storage have been investigated. Clarity, color, total phenols, total proteins, total sugars, total soluble solids (TSS), pH, and some specific polyphenols of juices were evaluated. Results show that at conditions of PES-10 kDa, CFR 30 L/hr, and TMP 0.75 MPa, a clarified juice obtained with color 0.15 A, clarity 96.94%, TSS 9.55 °Brix, pH 4.2, and total phenols, total proteins, and total sugars were 64.12 and 13.20 μg/ml and 50.70 mg/ml, respectively. Chlorogenic acid, epicatechin, phloridzin, catechin, and caffeic acid decreased differently from 32.63, 17.33, 3.25, 7.58, and 0.75 μg/ml to 17.24, 12.38, 1.79, 5.27, and 0.25 μg/ml, respectively. Storage in refrigeration for 4 weeks, clarity, total sugars, and total phenols reduced by 2.5%, 6.4%, and 16.6%, respectively, while TSS increased by 3.1%.