Effects of environmental factors on two-stage co-precipitation of tetragalloylglucose with three different proteins [bovine serum albumin (BSA), lysozyme, and myoglobin] were investigated. Factors such as pH, temperature, and ionic strength, mainly affected the second precipitation stage. On the other hand, protein concentration mainly affected the initial complexation stage. Precipitability of the galloylglucose-protein complexes is directly related to the solubility of the original protein under each environmental condition. (C) 1997 Elsevier Science Ltd.