Search

Native corn starch has a lack of characteristics such as low thermal stability, low resistance to shear force, and a high tendency to retrograde. To address this problem, it needs to be modified to improve its application in the food sector. Hydrothermal modification is one of the physical modifications by heating the starch above the gelatinization temperature with a limited water content. In this study, native corn starch was modified using various methods of hydrothermal modification which did not cause full gelatinization of starch and maintained starch granule integrity i.e., heat-moisture treatment (HMT), autoclave-heat treatment (AHT), microwave-heat treatment (MHT), and osmotic-pressure treatment (OPT). HMT, AHT, and MHT were modified by limited moisture content (30%) and then was heated using an oven, autoclave, and microwave, respectively, while OPT was heated in Na2SO42- solution using an autoclave. The results showed that the thermal modification did not alter the A-type crystallinity pattern of its native starch, but an amylose-lipid complex occurred resulting A + V-type crystallinity pattern. AHT starch has the highest V-type peak which indicated the highest amylose-lipid complex. The relative crystallinity increased after modification treatment except for OPT. The thermal modification increased thermal stability and increase the retrogradation ability of native corn starch. Parameters of thermal characteristics such as To, Tp, and Tc increased and Range of Tc – To decreased (except for HMT) after thermal modification. Solubility, water absorption capacity, gel strength, and syneresis of native corn starch tend to increase after modification. The best thermal modification of corn starch was OPT because it can produce the modified starch that not only had the highest thermal stability but also a lower retrogradation ability, the lowest swelling volume, higher water absorption capacity, and gel strength. Therefore, the hydrothermally modified corn starch could be applied to canned food, noodle, and bakery. [ABSTRACT FROM AUTHOR]

Crystalline pattern, granular morphology, physicochemical and pasting properties of banana starch and flour from three cooking banana cultivars (Kapas, Kepok and Nangka) and one dessert banana cultivar (Ambon) were compared. The result showed that cooking banana had a B-type crystalline pattern, while the dessert banana exhibited a C-type crystalline pattern. The flour exhibited higher crystallinity than the extracted starch. Nangka and Ambon starches possessed similar crystallinity (33–34%) while the crystallinity of Kapas starch (38.6%) was close to that of Kepok starch (39.4%). Elongated shape was typical of the starch granules of Kapas while spheroidal shape was seen in the rest of the cultivars. Cultivar did not significantly affect the swelling volume (SV) and solubility (except in Ambon cultivar) (p >.05) but determined water absorption capacity (WAC) and freeze-thaw stability (FTS) (p >.05). Ambon cultivar was the most stable to retrogradation while Kepok was the least stable which may be attributed to the different contents of amylose. Pasting properties, color and texture characteristics of starch were dependent on their cultivars and the presence of non-starch components. Non-starch contents increased the functional properties, pasting point and breakdown viscosity but decreased texture characteristics and setback viscosity. Kepok was the most resistant to gelatinization. Overall granule shape and starch crystalline type did not play any role in the different responses to the properties examined in the study but amylose content may have contributed to the freeze-thaw stability while crystallinity may have affected the starch pasting point. [ABSTRACT FROM AUTHOR]