Starch from tubers

Extraction of flour or starch from tubers, roots, or fruits Patent number GB1146854 (1969)... 

Digestion of raw starch from ground cassava tuber... 

Pectinase from Rhizopus sp. 26R showed high efficiency in enhancing the digestion of raw starch from whole cassava tuber when it was mixed with the glucoamylase. At the 1 hour of the reaction, the mixed enzymes gave the most efficient digestibility with hydrolyzation rate twice faster, than that when glucoamylase was used alone and about 3 times faster than when pectinases... 

According to the ability of the pectinase of Rhizopus sp. 26R that could efficiently enhance the hydrolyzation of raw starch from whole cassava tuber. 

When Rhizopus sp. 26R was cultivated in the solid substrates without addition of rice bran but composed of only wheat bran and rice husk at the ratio of 18 2. The pectinase activity from the culture was approx. 25-35 unit/ml within 2 days and the production remained constant for 4 days (Figure 3). One gram of raw starch from cassava tuber, 1 g of pectin or 0.5 g of yeast extract was added to the solid substrates in order to induce higher activity of the enzsrme. The results showed that either 1 g raw cassava starch or 1 g pectin that was added to the 20 g solid substrates increased the enzyme activity to 1.7 and 2.4 times, respectively (Figure 3). The production of pectinase in soHd substrates with wheat bran and rice husk could be enhanced with the addition of raw cassava starch and pectin. 

Figure 3 Pectinase activity in 20 g of solid substrates composting of wheat bran, rice bran and rice husk (18 0 2) with the addition of 1 g raw starch from cassava tuber, 1 g pectin or 0.5 g yeast extract.

Yusuph, M., Tester, R. F., Ansell, R., Snape, C. E. (2003). Composition and properties of starches extracted from tubers of different potato varieties grown under the same environmental conditions. Food Chem., 82,283-289. Zhu, Q., Bertoft, E. (1996). Composition and structural analysis of alpha-dextrins from potato amylopectin. Carbohydr. Res., 288, 155-174. 

Paste properties of native starches from different botanical origins have been reviewed.92,133 Relevant to practical usage of starch, the most important paste properties are viscosity, texture, paste transparency, resistance to shear and tendency to retrograde. In terms of texture, the translucent potato starch pastes can be described as cohesive, long-bodied, stringy and rubbery. Other root, tuber and waxy starches give pastes of similar texture to that of potato starch, but are generally less cohesive. On the other hand, pastes from common cereal starches are opaque and can be described as noncohesive and short- and heavy-bodied. These and other properties of several native starches are summarized in Table 8.1. 

Geddes, R., Greenwood, C. T., and Mackenzie, S. 1965. Studies on the biosynthesis of starch granules. Part III. The properties of the components of starches from the growing potato tubers. Carbohyd. Res. 1, 71-82. 

Starch is the most common polymer found in plants. Large amounts of starch can be obtained from tubers such as potatoes, from cereals such as rice, and from seeds such as corn. The starch molecule is heavily hydrated as it contains many exposed hydroxyl groups, which form hydrogen bonds on coming into contact with water. Starch is constituted of linear polymers (amylose) and of branched polymers... 

Starch [9005-25-8], (C6H10O5)k, the main reserve food of plants, constitutes two-thirds of the carbohydrate caloric intake of most humans but only 47% of the carbohydrate caloric intake by Americans, who also get about 52% of their carbohydrate calories from sugar. Commercial starches are obtained from seeds, particularly com, waxy com, high amylose com, wheat, and rice, and from tubers or roots particularly potato, sweet potato, and tapioca (cassava). Their principal use is in foods the major nonfood uses are in sizing of paper and textiles, and as adhesives (qv). 

CGTase from B. clausii strain El 6 was specific for P-CD formation displaying a P-CGTase action. The distributions of a-, P-, and y-CDs were 0, 89, and 11%, respectively, on soluble starch. The starches from different botanical sources influenced quantities and types of CD formed. It was also observed that root and tuber starches were more accessible to CGTase action. The process of starch homogenization can interfere whit the CGTase action and, consequently, on the CD formation. The gelatinization of starches by the autoclave process improves the CD production, mainly for cereal starches. 

Starch isolation from tubers/roots involves washing and peeling the tubers. The tubers are soaked in an aqueous solution of sodium bisulfite to prevent discoloration. The tubers are ground by a cylindrical drum containing rotary blades. Starch is isolated from other cellular components by centrifugation. 

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