Abstract:
This study investigates the formation and properties of compatible binary colloidal blends
between pre-gelatinized (uncomplexed and complexed with stearic acid) maize starches
(hydrophilic component) and commercial zein (hydrophobic component) with the aim of
creating a bipolymeric material with unique properties. The blends were formed under alkaline
condition (0.1 M NaOH) with 3:1, 1:1 and 1:3 starch: zein (w/w) ratios. The 3:1 starch-zein
blends showed best stability or compatibility. Blends made with starch complexed with stearic
acid had better stability than those with uncomplexed starch. Most of the blends were not freezethaw
stable except for 3:1 starch (complexed with stearic acid)-zein blend . The blends with
better stability had higher apparent viscosity , and a microstructure showing uniform mix of
starch – zein as observed by confocal laser scanning microscopy. The likely reason for the
compatibility of starch and zein is the change in surface activity of zein, possibly due to
deamidation, in 0.1 M NaOH as shown by the negative zeta potential values. The pre-gelatinized
maize starches also show negative zeta potential values. In conclusion, compatible binary
colloidal blends can be produced between pre-gelatinized maize starch and commercial zein
using 0.1 M NaOH.
