Effect of water content and mucilage on physico-chemical characteristics of Yam (Discorea alata Purpurea) starch

Published Date
November 2009, Vol.95(1):106–114, doi:10.1016/j.jfoodeng.2009.04.014

Title 
Effect of water content and mucilage on physico-chemical characteristics of Yam (Discorea alataPurpurea) starch

• Author 

• An-I Yeh ^a,,
• Tzu-Yin Chan ^a
• George Chao-Chi Chuang ^b,1,

• aGraduate Institute of Food Science and Technology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 106, Taiwan
• bDepartment of Hospitality Management, Mingdao University, 369 Wen-Hwa Road, Peetow, Chang Hua, Taiwan

Received 7 March 2008. Revised 10 April 2009. Accepted 18 April 2009. Available online 4 May 2009.

Abstract

Effects of water content and mucilage on physico-chemical characteristics of yam (Discorea alata Purpurea) starch have been investigated. Particle size analysis by laser light scattering showed the size of the isolated yam starch granules to be mostly in the range of 10–80 μm, and about 1% of starch granules was smaller than 1 μm. Decreasing water content from 90% to 40% did not significantly alter the onset temperature (T_o) and peak temperature (T_p), but raised the conclusion temperature (T_c). Mucilage exhibited greater storage modulus (G′) and smaller loss modulus (G″) than the isolated yam starch at water content of 90%. Water content also influenced the effect of mucilage on the rheological properties of starch–mucilage mixture, but did not significantly affect T_o and T_p. The swelling power measurement and scanning electron microscopy illustrated the presence of mucilage to retard the pasting of starch granules during heating.

Keywords

Yam starch

Mucilage

Swelling power

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• ⁎ 
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