The Influence of Ultrafiltration of Citrus limon L. Burm. cv Femminello Comune Juice on Its Chemical Composition and Antioxidant and Hypoglycemic Properties

Membrane separation has brought about a significant change in the food processing industry because it could operate separation at low temperature without a reduction of nutrients and bioactive compounds. Citrus limon L. Burm. cv Femminello comune juice, an Italian IGP (Protected Geographical Indication) product, was subjected to the ultrafiltation (UF) process using a cellulose acetate membrane, with a cut-off of 100 kDa, subjected to different transmembrane pressures (TMP, 05-1.5 bar). Untreated and ultra-filtrated (UF) juices were investigated for physicochemical parameters including pH, titratable acidity (TA), total soluble solids (TSS) and ascorbic acid content. Total phenols (TPC) and flavonoids (TFC) contents were also determined. Rutin, hesperidin, eriocitrin, and neohesperidin were selected as markers and quantified by HPLC. Antioxidant potential was investigated by using DPPH, ABTS, and FRAP tests. RACI was used to identify the sample with highest antioxidant potential. The hypoglycemic activity was examined using carbohydrates hydrolyzing enzymes assay. The application of increasing pressures across the membrane led to a reduction in TSS without causing a loss of bioactive compounds in terms of TPC and TFC. UF juice obtained with TMP of 1.5 bar (J3) showed a significant amount of eriocitrin and hesperidin with concentrations of 15.8 and 10.5 mg/100 mL, respectively. This sample showed the highest antioxidant potential and exhibited a promising alpha-amylase and alpha-glucosidase inhibitory activity with IC50 values of 31.1 and 35.3 mg/mL, respectively. Collectively our results support the use of cellulose acetate membrane to obtain an ultra-filtered juice with significant health potential.