LAUSR

ABSTRACT Impact of high-speed jet (HSJ) treatment on morphology, crystalline structure, retrogradation, thermal and rheological properties of Arenga pinnata (Wurmb.) Merr starch (APS) was investigated. Decreasing with the number of HSJ treatment passes were the turbidity values of pastes (long-term retrogradation), the gelatinization enthalpy, and the crystallinity. Scanning electron microscopy showed APS granule structure was degraded into tiny round particle and thin sheet structures. X-ray diffraction illustrated that the C-type X-ray pattern was changed toward a weak A-type X-ray pattern. With further increases in the number of passes, the weak A-type pattern was changed to amorphous pattern. Dynamic oscillation analysis revealed that HSJ treatment significantly altered the viscoelasticity of APS. During a dynamic frequency sweep, G′ values and G″ at 10 Hz decreased from 589.9 Pa (HSJ0) to 194.9 Pa (HSJ8) and from 101.6 Pa (HSJ0) to 24.5 Pa (HSJ8), respectively, implying that HSJ treatment had a great influence on the elasticity of the APS gel. The results indicated that degradation of APS granular and crystalline structure was mainly involved and HSJ treatment was a potential physical modification technique.