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|a (KIS3G)CLAS02vtls000012028
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|a Sajeev, Moothandassery S.
|4 aut
|9 1071687
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| 245 |
1 |
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|a Gelatinisation Characteristics of Cassava Starch Settled in the Presence of Different Chemicals
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|a Summaries. Addition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (To), temperature at peak minimum (Tp) and end temperature (Te), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crys-tallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.
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|a Conclusions. It can be concluded from the present comparative study on the gelatinisation and pasting properties of native and treated cassava starch samples that the chemicals affect the granular properties, the extent of which depends on the type and concentration of chemicals. The gelatinisation temperatures To, Tp and Te were generally found to be enhanced by chemical treatments. Of all the treatments the acid treatment had the most pronounced effect. A broadening of the gelatinisation temperature range was also observed at higher concentration of acids. Changes in AH values were not significant except for hydrochloric acid showing that during heating, most of the changes are taking place in the amorphous region of the granules only. With hydrochloric acid, the crystalline region is also affected to a small extent at higher concentrations. The use of even very dilute acids or alum at low concentrations during settling can lead to rapid deterioration in viscosity. In contrast, sodium metabisulphite and sodium hypochlo-rite do not affect the pasting characteristics at low concentrations. Thus our study revealed that among the different chemicals used for settling, sodium hypochlorite at 0.35 mM and sodium metabisulphite at 3.12 mM concentration were most effective in facilitating settling of starch without affecting its qualities.
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| 700 |
1 |
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|a Moorthy, Subramoni N.
|4 aut
|9 1071688
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| 700 |
1 |
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|a Kailappan, Ramasami
|4 aut
|9 1071689
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| 700 |
1 |
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|a Rani, Vijayalekshmi Sunitha
|4 aut
|9 1071690
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| 773 |
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|t Starch/Stärke
|b Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA, 2003, vol. 55, num. 5, s. 213-221
|x ISSN 0038-9056
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| 856 |
4 |
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|u http://www.viks.sk/chk/star_5_03_213_221.doc
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