Characterization and Studies on Physico-chemical properties of Sago Starch and its Oxidized Forms at Different Level Sago Palm Growth Stages

• Main Author: Awang Zulfikar Rizal, Awang Seruji
• Format: E-Thesis
• Language: English
• Published: Universiti Malaysia Sarawak(UNIMAS) 2016
• Subjects: QP Physiology
• Online Access: http://ir.unimas.my/id/eprint/30589/1/Characterisation%20and%20functional%20analysis%20of%20isochorismate.pdf; http://ir.unimas.my/id/eprint/30589/
• Institution: Universiti Malaysia Sarawak

The purpose of this study was to investigate the effects of growth stages of sago palm on the physico-chemical properties of oxidized sago starch. Sago starch of five different growth stages of sago palms namely Plawei, Plawei Manit, Bubul, Angau Muda and Angau Tua were extracted from top and bottom heights and oxidized with sodium hypochlorite in an aqueous alkaline medium. The characterization of physico-chemical properties of sago starch involved the determination of starch content, colour (L), clarity, carbonyl content, carboxyl content, viscosity, retrogradation profile, particle size and swelling factor analysis. From the study, it was found that the starch content increases as the palms matured from Plawei to Angau Muda and decreased at Angau Tua stage. The highest L values was recorded for the Plawei Manit top growth level (91.31%) with 5% chlorine level. The L of unmodified starch of 74.69% increased by 13.8% at Plawei top to 88.45% after the treatment through 5% chlorine level. At Bubul stage, the clarity improved from 6.10% to 49.76% after treatment with 5% chlorine level. The carbonyl and carboxyl content of oxidized sago starch increases significantly as the oxidation level increases at p<0.05 where top and bottom Plawei Manit showed a significant increase of carbonyl content at 5% chlorine level valued at 0.22% and 0.23%, respectively. These results showed the existence of the carbonyl and carboxyl group in the modified starch. Plawei top, Plawei Manit top, Plawei Manit bottom, Bubul top, Bubul bottom, Angau Muda top, Angau Muda bottom and Angau Tua bottom had a lower swelling power as compared to unmodified starch at oxidation level at 1%. The granules are found to be distributed based on height with most of the granules at top height are of smaller size while at the bottom height the starch has larger granules. The greatest granule size distribution was observed in the top height of Plawei top stage (19.51 to 39.35 μm). The peak viscosity decreases significantly with the increase of oxidation level for all growth stages from 751.5 AU to 219.5 AU as recorded at Plawei top stage. The enthalpies of gelatinization of the oxidized starch for all growth stages on both heights decreases as compared to their native starch. The retrogradation enthalpies were 60 - 70% lower as compared to the gelatinization and showed no specific trend of native and oxidized sago starch. The morphology of the oxidized sago starch was slightly rough. In conclusion, at Bubul stage the physico-chemical properties are comparable to Angau Muda stage and ready to be harvested for consumption and industrial applications.