Disclosed is a continuous process for separating or extracting proteins from a low grade mixture of a protein of interest, other proteins, impurities, and salts in a continuous simulated moving bed separation process. The invention provides for direct extraction of heme protein and plant protein from a crude mixture of such proteins, other proteins, impurities and salts using the chromatographic technique of simulated moving bed (SMB) continuous chromatography. The SMB process combines the steps of feed loading, adsorbent washing, product elution, adsorbent regeneration, and adsorbent equilibration. The novel strong anion exchange resin adsorbent is a quaternary amine cross-linked microcellulose wherein the microcellulose is cross-linked with epichlorohydrin and the quaternary amine is 2,3-epoxypropyltrimethyl-ammonium chloride which exhibits selective adsorption of proteins and complete regeneration. Purified protein separated in this manner may provide human health benefits by providing greater medicinal and nutrition opportunities from low quality protein sources.