Comparative Susceptibility Of Sago, Corn And Potato Starches Towards Acid And Alkaline Treatments
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Date
2011-07
Authors
Mohd Zaki, Nor Nadiha
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Publisher
Universiti Sains Malaysia
Abstract
The effects of steeping starch (sago, corn, and potato) in 0.025 M of sodium hydroxide and hydrochloric acid for 0, 15, and 30 days at 30°C on its granular structure and other physicochemical properties were investigated. Changes in the morphology of starch granules indicated that the alkaline and acid solution affected the granular structure of the starch to different extent, depending on starch type and their botanical sources. Pasting studies showed that the peak viscosity, breakdown, and setback of alkali-treated sago and potato starch decreased significantly, whereas that of corn starch increased significantly, when steeping time was prolonged. Meanwhile, acid-treated sago, corn, and potato starch showed significant decreased in peak viscosity, and breakdown. Setback viscosity increased significantly for 30 days in acid-treated sago starch but decreased significantly for acid treated potato starch. Swelling power increased significantly for alkali-treated potato and corn starches, but decreased for sago starch. However, swelling power of sago starch showed an increase when treated with acid solution, whereas acid-treated corn and potato starch showed significant decrease. The amylose content of all acid-treated starches decreased significantly after treatment, but alkali treated sago and corn starch did not shows any significant difference, in fact shows the higher amylose content for alkali-treated potato starch. Onset and peak temperatures of gelatinization (from a differential scanning calorimeter measurement) increased significantly. Acid-treated corn starch shows the highest solubility compared to other treated starch. Results shows the significant increased in acid treated corn and potato starch, while there was a slight decreased of acid-treated sago starch compared to alkali-treated sago starch. For retrogradation, the peak temperature showed a significant decrease for all treated starches. The enthalpy of acid and alkali treated sago and potato shows a significant decrease, meanwhile alkali and acid treated corn starch shows no significant changes. There are no significant changes of chain type when compared to their native starch. The results showed that the physicochemical properties of starch from various botanical origins were affected to variable degrees when treated with alkaline and acid solution.
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Keywords
The effects of steeping starch , on its granular structure