earticle

영어

Granular maize starch was treated with Thermus scotoductus 4--glucanotransferase (-GTase), and its physicochemical properties were determined. The gelatinization and pasting temperatures of -GTase-modified starch were decreased by higher enzyme concentrations. -GTase treatment lowered the peak, setback, and [mal viscosity of the starch. At a higher level of enzyme treatment, the melting peak of the amylose-lipid complex was undetectable on the DSC thermogram. Also, -GTase-modified starch showed a slower retrogradation rate. The enzyme treatment changed the dynamic rheological properties of the starch, leading to decreases in its elastic (G') and viscous (G") moduli. -GTase-modified starch showed more liquid-like characteristics, whereas normal maize starch was more elastic and solid-like. Gel permeation chromatography of modified starch showed that amylose was degraded, and a low molecular-weight fraction with Mw of 1.1 x 105 was produced. Branch chain-length (BCL) distribution of modified starch showed increases in BCL (DP>20), which could result from the glucans degraded from amylose molecules transferred to the branch chains of amylopectin by inter-/intra-molecular transglycosylation of -GTase. These new physicochemical functionalities of the modified starch produced by a-GTase treatment are applicable to starch-based products in various industries.