The rheological properties of pectin were determined by rheometer (AR1000, TA instruments, USA) with a 20 mm parallel plate. The solution for rheological tests was prepared by mixing pectin with distilled water (2%, w/w). The sample solutions were subjected to steady-shearing at 25
C with the shear rates ranged from 0.02-100 s
1
. Oscillatory measurements were used to determine the storage modulus (G
0
) and loss modulus (G
) of pectin solutions. Strain sweep (0.01e100% at 1 Hz) was applied to test the linear viscoelastic region of the samples. And the frequency dependence of G
0
and G
was determined by a frequency sweep (0.1e10 Hz at 1% strain) (