Contribution of Charged Amino Acids to Improving the Degraded Viscosit of Potato Starch Paste by a Retort Treatment and during Storage

Abstract

The effects of lysine (Lys), monosodium glutamate (GluNa), glycine (Gly) and alanine (Ala) on the viscosity, turbidity, morphological features, solubility of saccharides and molecular size distribution of the dissolved saccharides in retorted potato starch paste were investigated. Gly and Ala with zero net charge-containing pastes showed a large decrease in the viscosity due to collapse of the swollen starch granules by the retort treatment, whereas GluNa and Lys with a positive or negative net charge could inhibit such viscosity change and collapse of the starch granules. The turbidity of GluNa- and Lys-containing pastes evaluated by the absorbance at 500 nm was higher than that of Gly- and Ala-containing pastes. The dissolved saccharides for each retorted paste mainly consisted of low-molecular-weight molecules below M_r 600. GluNa and Lys could strongly suppress the increased viscosity and turbidity of the retorted paste during storage for 7 days at 5 and 55°C, although Gly and Ala had little effect. The charged amino acids could thus be applied to improving the viscosity and turbidity of the retorted starch paste by maintaining the swollen starch granules.