Novel uses of modified cassava starch in the Asian food industry.

A study was carried out on the effect of temp. and pH on the cross-linking reaction of cassava starch with sodium trimetaphosphate. It was found that temp. of 45 plus or minus 2.0 and 50 plus or minus 2.0 degrees C and a pH range of 10.0-11.5 does not affect significantly Brabender viscosity of starch paste at 95 degrees C. In an aqueous starch suspension, by increasing the concn. of sodium trimetaphosphate and the reaction time, while keeping the temp. at 45 plus or minus 2.0 degrees C and pH at 10.0, the degree of cross-linking increased. Concurrently to the increase of cross-linking, the viscosity of the starch paste became more stable and its pasting temp. increased. The optimum viscosity and stability of the cross-linked starch were achieved by using 1.4 percent sodium trimetaphosphate and a 16 h reaction time. By recording paste properties, the increase in the extent of cross-linking with time was determined. By increasing the trimetaphosphate concn. the residual starch phosphate as well as the viscosity of the starch paste increased when held at 50 degrees C for 30 min and in a pH range of 3.0-5.0. Also, the increase in the extent of cross-linking brought about a decrease in the starch granules' swelling power. The viscosity pattern of cross-linked cassava starch paste, made from an 8 percent starch suspension, was very close to that of native mungbean starch. Hence, the results were applied in manufacturing mungbean noodles, i.e., cassava starch, cross-linked with the use of 2 percent trimetaphosphate, was used to partially substitute for mungbean starch. The organoleptic evaluation of mungbean noodles made from 50 percent of such cross-linked cassava starch, showed no significant difference from grade A mungbean noodles prepared from 90 percent mungbean starch and 10 percent native cassava starch. The price of cassava is about 5 times cheaper than mungbean starch. Thus, utilization of cross-linked cassava starch in mungbean noodle manufacturing can substantially reduce its cost of production.