Starch Cassava

Pectinases from Rhizopus sp. Efficient in Enhancing the Hydrolyzation of Raw Cassava Starch Purification and Characterization... 

Microorganism Rhizopus sp. 26R, a fungal strain isolated in Thailand which capable of hydrolyzation of raw cassava starch (Figure 1). 

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. 

Addition of rice bran to the solid substrates to make the ratio of wheat bran, rice bran and rice husk to 9 9 2 helped increasing the activity of pectinases from Rhizopus sp. 26R as shown in Figure 4. The activity of the enzyme was approx. 4.3 times higher. Moreover, either 1 g of pectin or 0.5 g of yeast extract did not help increasing of the enzyme production. In contrary, the enz5mie activity was decreased 2.6 times to that of the former one. Addition of raw cassava starch to the substrates did no effect to the enzyme production (data not shown). 

The efficiency in raw cassava starch hydrolyzation of pectinases from Rhizopus sp. 26R compared with a commercial pectinase when mixed with Glucoamylase from Aspergillus niger J8. 

When compare the efficiency in enhancing the hydrolyzation of raw cassava starch between pectinases from Rhizopus sp. 26R and the commercial pectinase at periods of time (Figure 10). 

While using of commercial pectinase with glucoamylase showed less efficient in enhancing the hydrolyzation of starch. In the 2nd, 4th, 6th and 8th hours, the commercial one could enhance the hydrolyzation only 1.2, 1.4, 1 and 1 time, respectively. Therefore, pectinases of Rhizopus sp. 26R was more efficient in enhancing the digestion of raw cassava starch more than the commercial one when used with glucoamylase. 

The production of the pectinases in the sohd substrates composed of wheat bran, rice bran and rice husk (6 12 2) was considerably very low. The spore inoculum of Rhizopus sp. 26R was prepared on raw cassava starch agar which the cost estimation was US 1.0 per 1 litre. Wheat bran, rice bran and rice husk were approx. US 64 per 50 kg. The total cost of the production of pectinases from Rhizopus sp. 26R in the sohd substrates, when considered only on the substrates was estimated to be only US 178 - 180 for 10 million units of crude pectinase. 

The enzyme production in the solid substrates composed of wheat bran and rice husk (18 2) could be increased by the addition of either 1 g raw cassava starch or 1 g pectin to a 20 g substrates. The enzyme activity increased approx. 1.7 and 2.4 times, respectively. 

Addition of rice bran to the mixture of wheat bran and rice husk was the best substrates for the fungal pectinase production. The solid substrates that composed of wheat bran, rice bran and rice husk at the ratio of 6 12 2 was selected to be the best since rice bran are easily found in South-east Asian countries. Addition of either raw cassava starch or pectin as inducer is not needed. On the otherhand, pectin even inhibited the activity of the enzyme as well as that reported by Elegado and Fujio (6). 

Tapered module design, 15 835 Tapholes, blast furnace, 14 505-507, 509 Taphonomy, 5 752 Tapioca/cassava starch, 4 724t Tapping mode, in atomic force microscopy, 77 63 Tapping-mode AFM, 24 84 Tapping mode atomic force microscopy (TMAFM), 14 465, 16 501 Taq polymerase, 72 513 Taquidil... 

Jyothi, A. N., Sasikiran, K., Sajeev, M. S., Revamma, R., and Moorthy, S. N. (2005). Gelatinisa-tion properties of cassava starch in the presence of salts, acids, and oxidizing agents. Starch/Starke 57,547-555. 

Glycosides cvanoeenic prunasin (Ang. BR) linamarin (Euphorbiaceae, Ang., notably found in Cassava starch BR) amygdalin (seeds ofRosaceae, Ang. BR). 

Glucose syrup solids from wheat, rice, and cassava starches. A... 

Glucose syrups, also known as com syrups in the United States, are defined by the European Commission (EC) as a refined, concentrated aqueous solution of D(+)-glucose, maltose and other polymers of D-glucose obtained by the controlled partial hydrolysis of starch (Howling, 1984). Glucose syrups were fust manufactured industrially in the nineteenth century by acid hydrolysis of starch. Hydrochloric acid was normally used, because sulphuric acid caused haze in syrups due to insoluble sulphates. The source of starch can vary in the United States corn is widely used, whereas in other parts of the world wheat, potato and cassava starch are also employed. Acid hydrolysis of starch is still used today. The method is non-specific, but if conditions are tightly controlled, it is possible to make products with a reasonably consistent carbohydrate profile. 

Solid com and cassava starches have been irradiated with 337.8-nm pulsing ultraviolet light (2.6 ns with a peak power of 100 kW) emitted by an atmospheric-pressure nitrogen laser.270a Small changes could be observed in the water solubility of the irradiated starches, their water-binding capacity, and the iodine uptake, provided that promoters (1% w/w) were introduced. The activity of three promoters tested—ZnO, TiOz, and MgO—and the susceptibility of both starch varieties to the irradiation were approximately the same. 

The effect of microwave radiation on maize, potato, and cassava starch (all either air-dried, in slurry, or pregelatinized) has been studied by Muzimbaranda and Tomasik.295a Starch readily dextrinized under such treatment. The sensitivity to microwaves increased in the order com > cassava >> potato starch. Micro-wave radiation also allowed facile cross-linking of starch with formaldehyde. The reaction took place for 5-15 min. and did not require any catalyst. Extended periods of reaction led to dextrins. In the presence of hydrogen peroxide, starch could be cross-linked with acetylene.2953... 

Figure 12.3 Basic process for isolating a high-quality tapioca/cassava starch. The numbers in parenthesis represent the mass balance (tons/day) and cyanide balance (kg/day) of a factory with the production of capacity 200 tons of tapioca/ cassava starch per day. (Modified from Sriroth et al.23 and Piyachomkwan et al.24)...

The quality of tapioca starches produced can be affected by fresh root quality, as well as the production practices of each factory. Nevertheless, commercial tapioca starches always comply well with industrial specifications which differ to some extent, depending on the manufacturers and end users. General specifications of cassava starch are summarized in Table 12.3. 

Table 12.3 General specification of native cassava starch...

Figure 12.6 Changes in granular structure of cassava starch extracted from roots (a) planted during the rainy period and harvested at 6 months (b) planted during the rainy period and harvested at 12 months (c) planted during the dry period and harvested at 6 months (d) planted during the dry period and harvested at 1 2 months, when observed by hot-stage microscopy at different temperatures.

Starch modifications can be classified as physical modifications, chemical modifications and genetic modifications.45 Physical modification of cassava starch involves application of shear force, blending and thermal treatment. A combination of thermal treatment and shear force has been widely used to produce many extruded products and snacks. Well-known physically modified cassava starch products are alpha starch or pregelatinized starch and heat-moisture treated starch. 

Heat-moisture treated starch, sometimes called Tao starch in Thailand, is prepared from cassava starch by heating moistened starch (—50% moisture content) at various temperatures and times. Heat-moisture treatment provides a modified starch that produces a less cohesive, shorter-textured paste with improved shear resistance and gel properties, as compared to the long, stringy, cohesive paste of native tapioca starch. 

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