Calcium Binding of Two Microalgal Polysaccharides and Selected Industrial Hydrocolloids

摘要

ABSTRACTBinding of calcium ions to polysaccharides from two freshwater microalgae,Palmella texensis(UTEX 1708) andCosmarium turpinii(UTEX LB 1042) (PTP and CTP, respectively), and six industrial hydrocolloids was studied. The amount of bound calcium decreased with a decrease in pH below 6. Scatchard analysis showed that PTP, guar and locust bean had low calcium affinity and one type of binding site. Alginate bound calcium with the greatest affinity (k= 1.31 × 106) among the hydrocolloids examined and appeared to have one type of binding site. Gum arabic and CTP appeared to have two types of binding sites. The order of magnitude of uronic acid in each hydrocolloid did not agree with the order of calcium binding affinity as an intrinsic association constant indicating limited importance of the chemical nature of hydrocolloids to the effect of linear charge density