Physico-chemical properties of starch in sago palm (Metroxylon sagu) at different growth stages

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dc.contributor.authorStages Adrina Tie Pei, Lang
dc.date.accessioned2014-11-14T07:49:14Z
dc.date.available2014-11-14T07:49:14Z
dc.date.issued2005
dc.descriptionMasteren_US
dc.description.abstractThis study aimed to characterise the physico-chemical properties of sago starch from base and mid heights of palms at different growth stages, namely, ‘Plawei’, ‘Bubul’, ‘Angau Muda’, ‘Angau Tua’ and ‘Late Angau Tua’. The starch content and the composition of associated components in the sago pith were determined as well. The characterisation of physico-chemical properties of sago starch involved determination of swelling factor, particle size and distribution profile, flow behaviour of the starch paste, pasting characteristics and retrogradation profiles analysis. The starch content was found to increase as the palms matured from Plawei to Angau Muda stages and decrease from Angau Tua to Late Angau Tua stages. The scanning electron micrographs of sago starch showed oval-shaped granules of 10 - 30 μm in different proportion. Variation was observed in the granule size of starch whereby the starch at base height of all the stages was larger in mean diameter than mid height. The pasting profile showed four different pattern of pasting curves from the combination of the mean results. No prominent variation was observed in the results of swelling factor, flow behaviour measurement and thermal properties of sago starch from the different growth stages. All the starch samples showed the highest swelling factor at 70 °C. The best fit curve of shear stress versus shear rate indicated all the samples fitted the Herschel-Bulkley model. The relationship between the log viscosity and log shear rate suggested that the starch dispersion is susceptible to shear-thinning or pseudoplastics behaviour. The thermal profile showed similar thermograms with To in the range of 70.2 - 73.1 °C, Tp of 75.1 - 77.0 °C, Tc of 97.4 - 101.4 °C and ΔHG of 17.5 - 19.2 Jg-1 in all the starch samples. Similarly, the thermograms of retrograded starch showed a broad endotherm occurring at transition temperatures of 25 - 29 °C and ΔHR of 8 - 9 Jg-1 lower than that of gelatinised starch. No significant difference was observed in the composition of associated components of sago pith from the different growth stages. The soluble carbohydrate ranged from 4.5 - 8.5 %. The phenolic compound was less than 1 % whereas the lignin content ranged from 9 - 22 %. The non-starch polysaccharides in the form of total, insoluble and soluble non-starch polysaccharides ranged from 57.5 - 105.4 %, 43.5 - 86.4 % and 12.4 - 23.9 %, respectively. In conclusion, the best stage for harvesting is Angau Muda stage whereas the variation in the physico-chemical properties of sago starch from base and mid heights of different stages will govern its application in the different industries according to the individual commercial needs.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/487
dc.language.isoenen_US
dc.subjectIndustrial technologyen_US
dc.subjectPhysicochemicalen_US
dc.titlePhysico-chemical properties of starch in sago palm (Metroxylon sagu) at different growth stagesen_US
dc.typeThesisen_US
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