Purification of polyphenols from apple skins by membrane electro-filtration

Dead-end electro-filtration of polyphenols extracted from apple skin was studied. The influence of membrane pore size (dm = 3.02-50 nm), transmembrane pressure (Delta P = 1-6 bar) and direct current (DC) electric field (U = 5-15 V) on the purification efficiency was investigated. The sieving ratios R of selected membrane UH030 (dm = 4.35 nm) towards the polyphenols, proteins, total solutes, and colour intensity increased with increase of transmembrane pressure. It was demonstrated that utilization of this membrane for the DC electro-filtration allowed more effective rejection of proteins at the anode part of the filter. Such effects can be attributed to the large size of protein molecules and their positive charge. Obtained data evidenced the possibility of selective purification of polyphenols by membrane electro-filtration.

Automated summary

The study found that increasing the transmembrane pressure can improve the sieving ratios of the membrane towards polyphenols, proteins, total solutes, and color intensity. Using a specific membrane for DC electro-filtration can effectively reject proteins and selectively purify polyphenols.