The loss factor, tan d represents the ratio of energy lost to energy
stored during a cycle (Ferry, 1970). During prolonged heating,
starch suspensions show a rise in G’ and reach a maximum and then
decrease which may depend upon the swelling factor and breakdown
resistance (Singh et al., 2003). Starch gels showed G’ and G’’
values at 90 C in the range from 17 Pa to 25 Pa and 10e12 Pa,
respectively. Lii et al. (1995) reported a G’ value at 95 C of 39 Pa for
rice starch (20%, w/w) with amylose content of 0.99%. The decrease
in G’ upon heating may be attributed to the deformation/loss of
granular structure due to melting of remaining crystallites in
swollen granules (Eliasson, 1986). Keetels et al. (1996b) hypothesized
and attributed the decrease in G’ on prolonged heating to
loosen non-covalent bonds by disentanglement.