Studies on Sago Starch. Part I: Characterization and Comparison of Sago Starches Obtained from Metroxylon sagu Processed at Different Times

Abstract

This paper reports on a study undertaken to determine some of the factors responsible for the variability shown by sago starch, which at present severely limits the commercial value of this material. Two batches of sago starch extracted from Metroxylon sagu species were characterized physicochemically and structurally. One batch was white in colour while the other was reddish‐brown. The latter contained significantly more protein (0.06%) than the former (0.015%). Non‐proteinaceous material constituted 40% of the total nitrogen in the former. The ionic contents of the two batches of starch exhibited a similar ion profile except for the following striking differences. The white batch contained 20‐fold more phosphorus and 15‐fold more aluminium whilst the reddish‐brown batch contained double the quantity of iron and calcium. The solubility and swelling capacity of both batches were also different. Amylographic representation was used to reveal the strength of starch granules during pasting. Scanning electron microscopy disclosed different degrees of pitting between the two batches, the morphology of which were also shown to be disparate. Flow curves also displayed significant differences in the rheological behaviour.