Physico-chemical properties of cross-linked tuber starches

I. Khatijah and H. Patimah

Abstract

The tapioca and sweet potato (var. Bukit Naga and Gendut) starches were modified to widen their uses. Modification was done by cross-linking the starches with sodium trimetaphosphate. The physico-chemical properties of the crosslinked starches were determined. The pasting characteristic and freeze-thaw properties of the cross-linked starches were similar to that of the commercial modified corn starch recommended for sauces. The residual phosphorus and phosphate contents were lower than the permitted levels specified by FAO/WHO and EEC. The modified sweet potato (Bukit Naga) starch had the least swelling power while the tapioca starch had the highest swelling power. For the modified sweet potato starches, a viscosity drop in the pasting cycle occurred at pH 3.7. In the case of modified tapioca starch, the viscosity drop was at pH 3.5. This indicates that the modified sweet potato starches are suitable for foods with pH≥3.7 while the modified tapioca starch is suitable for foods with pH ≥3.5.

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