Intriguingly, when 0.7% and 1.0%(w/v) xanthan solutions were extruded into 0.7%(w/v) chitosan solution, increases of chitosan pH from 4.5 to 5.5, first significantly increased the degree of swelling before it reached the lowest SD at pH 6.2. This significant increase in the SD when chitosan pH was raised from4.5 to5.5 might be associated with the slight decrease in the charge density of chitosan (ionization degree ca. 0.9) that lessens the ionic linkages between the two polymers, rendering higher SDs.