Effect of preservatives for food grade C-PC from Spirulina platensis

The effect of selected edible preservatives, citric acid, sucrose and calcium chloride on the stability of C-phycocyanin (C-PC) at 0 +/- 5 degrees C and 35 +/- 5 degrees C was studied in aqueous solution. While screening the edible preservatives for a protein like C-phycocyanin, the denaturation of C-PC with urea as a denaturant and thermal unfolding studies through differential scanning calorimetry (DSC) was carried out to select a stabilizing agent having Hofmeister series behaviour acting on hydrophobic interactions. While studying the efficacy of edible preservatives, citric acid (4 mg/ml) was observed to be one of the best preservative for phycocyanin at 35 +/- 5 degrees C in aqueous solution for 45 days with negligible loss which is comparable to the stability of C-PC at 0 +/- 5 degrees C. Calcium chloride and sucrose were also found to be effective in maintaining the stability of C-PC in aqueous phase, but at lower temperature. Citric acid was able to maintain the stability even at higher temperature lasting for more than 1 month in aqueous solution. (C) 2008 Elsevier Ltd. All rights reserved.