Optimization of preparation treatment for Granular-Cold Water Soluble (GCWS) sago starch

• Main Author: Kuan, Yau Hoong
• Format: Academic Exercise
• Language: English
• Published: 2007
• Subjects: TX341-641 Nutrition. Foods and food supply
• Online Access: https://eprints.ums.edu.my/id/eprint/7543/1/ae0000001551.pdf; https://eprints.ums.edu.my/id/eprint/7543/
• Institution: Universiti Malaysia Sabah

An attempt was carried out to study the optimum treatment condition for preparation of GCWS sago starch. The variables studied were ethanol concentration (40%, 50% and 60%) and sodium hydroxide proportion (1 g, 2 g and 3g with respect to 1 g of starch). A two-factor three level Faced-Centered Cube (FCD) Design consisting of thirteen runs was employed to produce GCWS sago starches. The physicochemical, morphological, and functional properties of the GCWS sago starches were studied using Response Surface Methodology (RSM). In this study, the GCWS sago starches were qualitatively and quantitatively measured for the percent of cold water solubility, swelling power, water binding capacity, particle size distribution, apparent amylose content, starch paste clarity, freeze-thaw stability and the apparent viscosity. Sodium hydroxide exhibited more pronounced effect on most of the responses studied as compared to ethanol. Sodium hydroxide was found significantly increased the cold water solubility (P<0.05), swelling power (P<0.05) and water binding capacity (P<0.05). Ethanol was found to decrease the cold water solubility (P<0.05) and water binding capacity (P<0.05); indicates the restriction of excessive swelling. Sodium hydroxide also caused amylose leaching (P<0.05). Light microscopic examination and particle size distribution found evidences that the starch granules swelled to rupture at high sodium hydroxide proportion. Finding on clarity postulated that all the treated and native sago starches exhibited retrogradation during storage at room temperature and refrigeration temperature 4°C. However, the GCWS sago starch pastes showed higher viscosities (P<0.05) and better freeze-thaw stabilities (P<0.05) than the native counterpart. Cold water solubility and particle size distribution were used to obtain the optimum treatment combination. Based on the superimposed plots, the optimum conditions were 45% ethanol concentration and 285 g of sodium hydroxide. The GCWS sago starch produced under the optimum conditions was analyzed to validate the model. The experimental values obtained for cold water solubility and mean particle size were 52.18 ± 1.45% and 25.42 ± 1.24 µm respectively. The experimental values agreed well (P>0.05) with the predicted values. Thus indicating suitability of the model employed and the success of RSM in optimizing the GCWS sago starch preparation using alcoholic-alkaline treatment.