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Showing papers by "Central Tuber Crops Research Institute published in 2003"


Journal ArticleDOI
TL;DR: In this paper, the properties of starch extracted from two species of Curcuma viz. C. zedoaria and C. malabarica were studied and it was shown that the starch from C. Zedoaria was slightly yellowish due to the presence of the yellow pigment, curcumin.
Abstract: The properties of starch extracted from two species of Curcuma viz. Curcuma zedoaria and Curcuma malabarica were studied. The starch from C. malabarica tubers was white in color, while that from C. zedoaria was slightly yellowish due to the presence of the yellow pigment, curcumin. The granule size and shape, amylose content and solubility did not show noticeable difference between starches from the two species. Both the starches possess “B” type x‐ray diffraction pattern. Curcuma zedoaria starch showed a lower peak viscosity and swelling volume when compared to C. malabarica starch. The complete removal of curcumin from C. zedoaria starch by alcohol extraction, resulted in an increase in the swelling and viscosity values close to those of C. malabarica starch. The breakdown in viscosity was quite low for both the starches and setback was higher when compared to cassava and sweet potato starches. The experiments showed that Curcuma starch resembles Dioscorea starches in most of its properties. Di...

52 citations


Journal ArticleDOI
TL;DR: The study clearly established that among the fourtechniques used, microwave baking and flour preparation were the best methods to eliminate TI from sweet potatoes and taro.
Abstract: In order to understand the extent of elimination of trypsininhibitors during processing of sweet potato (Ipomoea batatas) andtaro (Colocasia esculenta) tubers, a detailed study was conductedusing tubers processed by oven drying, cooking, and microwavebaking Between 80 and 90% trypsin inhibitor (TI) activity wasretained in sweet potato chips up to 2h at 70 °C Among thefour cultivars of sweet potatoes, RS-III-2 trypsin inhibitors were more heatlabile Heating at 100 °C led to rapid inactivation of TI of sweetpotatoes Varietal differences in thermal stability were more pronouncedfor the trypsin inhibitors of taro than sweet potatoes Taro inhibitors werealso more rapidly inactivated than sweet potato TI Between 17 and31% TI activity was retained in cooked tuber pieces of sweet potatoes,while only 3–10% were retained in taro cultivars Very effectiveinactivation of trypsin inhibitors of sweet potatoes and taro could beobtained through microwave baking Flour prepared from taro was devoidof TI activity, while 5–12% TI activity was retained in the flour preparedfrom sweet potatoes The study clearly established that among the fourtechniques used, microwave baking and flour preparation were the best methods to eliminate TI from sweet potatoes and taro

36 citations


Journal ArticleDOI
TL;DR: In this article, the effect of added 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.
Abstract: 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 (T-o), temperature at peak minimum (T-p) and end temperature (T-e), 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 crystallinity 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.

34 citations