A differential scanning calorimetric (DSC) study on the effects of annealing and sugars-emulsifiers on gelatinization of sago starch (Metroxylon sagu)
1999
Ghani, M.B.A. | Man, Y.B.C. | Hashim, D.M. | Rahman, R.A.
This study investigated the effects of annealing, at different temperatures (45-70 C), times (0-24 h) and water:starch ratios (0.6/1-4/1), on the DSC thermal properties profiles associated with gelatinization temperatures of sago starch-water mixtures. The effects of sugars-emulsifiers and of starch mixtures and their interactions were also investigated. DSC data showed an increased gelatinization temperature and enthalpy and a narrower gelatinization temperature range (Tm-To) after annealing of sago starch; the extent of these changes was inversely proportional to the degree of crystallinity of the native starch. For sago starch, the G transition occurring at about 66-69C and the M1 transition occurring at about 75 C in excess water became broader and shifted to higher temperatures as the water content was decreased. The effects on the gelatinization temperature and delta H, of the addition of sugars-emulsifiers to the starch-water mixture, were observed by comparison with the starch-water results. Sucrose raised the gelatinization temperature by about 6-7 C more than did glucose, for sago starch. Emulsifiers (sucrose ester and polysorbate-60), in the presence of sucrose or glucose, did not effect the gelatinization temperature.
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