GELATINIZATION OF STARCH IN AQUEOUS ALKALINE-SOLUTIONS

The effect of kind and concentration of alkali on the gelatinization o f maize, rice and wheat starches were thoroughly investigated. No gela tinization could be observed on using the carbonate and/or bicarbonate of sodium and potassium even on using their saturated solutions, whil e both sodium and potassium hydroxides undergo gelatinization. Gelatin ization of starch occurs immediately at a concentration of sodium hydr oxide of 1.2%, while clear gelatinized pastes could be obtained at 4% or more. Infra-red spectra of maize and rice starches before and after alkali treatment reveal that treatment of starch with sodium hydroxid e is accompanied by some physicochemical changes in the structure of s tarch. The theological properties as well as the apparent viscosity of the gelatinized starch pastes depend on the kind of starch as well as the nature and concentration of alkali used.