Abstract
Deproteinized wheat starch (Act-WS) was prepared by twice digesting with actinase large granular wheat starch classified from wheat starch that had been extracted with 70% ethanol. A small amount of preoteinaceous component still remained in Act-WS. The effect of lysine (Lys), monosodium glutamate (GluNa), glycine (Gly) and alanine (Ala) on the thermal behavior of Act-WS, and the dispersion state of the swollen starch granules in the Act-WS paste was investigated. Consequently, Gly and Ala had little effect on the gelatinization temperature and viscosity, whereas GluNa and Lys markedly elevated these parameters. This increased viscosity with Lys contrasted the results for potato starch. Such charged amino acids as GluNa and Lys reduced the swelling and solubility, while Lys elevated the turbidity, median diameter and ratio of aggregates of the swollen granules. The increased viscosity was thus caused by forming aggregates with Lys, presumably through interacting with a starch-granule-associated protein.
