Clarification and storage study of bottle gourd ( Lagenaria siceraria ) juice by hollow fiber ultrafiltration

Abstract

Ultrafiltration of bottle gourd juice was undertaken in this study using hollow fibers with the objective to have juice with long shelf life without heat treatment, preservatives and additives maintaining the natural taste, flavor and nutritional quality intact. Five blend hollow fiber membranes (M-1 to M-5) with 15 wt% polyacrylonitrile (PAN) and 5 wt% cellulose acetate phthalate (CAP) were prepared. No additive was used in M-1 membrane. For M-2 and M-3 membranes polyethylene glycol (PEG) of molecular weight 200 Da was used as an additive with concentration 1.5 and 3 wt%, respectively. 3 wt% PEG of molecular weight 1500 Da was used in M-4 and same concentration of PEG of molecular weight 4000 Da was used in M-5 membrane. The membranes were characterized in terms of permeability, molecular weight cut off, permeate flux, permeate quality and anti-fouling characteristics. M-3 membrane was selected based on performance. Experiments were conducted both in total recycle and batch concentration mode. In case of total recycle mode, transmembrane pressure drop (TMP) was varied from 35 to 104 kPa and that of cross flow rate (CFR) was from 10 to 20 l/h. Quality of the filtered juice was analyzed in terms of color, clarity, total soluble solid, polyphenol, concentration of protein, sodium and potassium. TMP 104 kPa and CFR 20 l/h were found to be suitable operating conditions for filtration. The filtered juice was stored for 8 weeks under normal refrigeration. All the nutritional parameters (total protein, polyphenol, sodium, potassium and total soluble solids) including taste were monitored and it was found that the quality of the juice was maintained with a positive purchase intention.