Effects of maize starch properties of heat-treatment with water-ethanol mixtures
1997
Kurakake, M. | Noguchi, M. | Fujioka, K. | Komaki, T.
Maize starch (1 part) was heated at 120 degrees C for 20 min in water-ethanol mixtures (5 volumes), in which the water content varied over the range 0-70%, and the product solvent-exchanged with acetone. On treatment with mixtures containing 40-60% water, the swelling power and solubility at 97 degrees C decreased and the differences between these values measured at 25 and 97 degrees C narrowed. The properties of starch treated with a mixture containing 30% water resembled those of heat-moisture treated starch. The values of deltaH and deltaS for swelling were greatly decreased by treatment in mixtures with a water content greater than 20-40% (O.39-0.63 mole fraction). Furthermore, the digestibility ratio of alpha-amylase (endo-type) to glucoamylase (exo-type) was at a maximum after treatment with a mixture containing 30% water. These findings suggest that rearrangements between the amylose and amylopectin in starch granules are occurring after treatment with mixtures containing more than 30% water. These changes in the starch granule are enhanced when the treatment temperature is increased to 100-130 degrees C.
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