Abstract:

The purpose of this study was to improve the stability of sour soymilk and accordingly prolong its shelf-life by
the combined addition of pectin and carboxymethyl cellulose (CMC). The optimization of pectin and CMC concentration
for improved Turbiscan stability index was performed using combination of single-factor experiments and response surface
analysis. The results indicated that adding 0.12% pectin and 0.40% CMC to sour soymilk proved optimal. The particle size
distribution of the stabilized system indicated that the particles of sour soymilk were well dispersed within the range of 0.04–8 μm
with a mean particle size D(4,3) of 1.68 μm. The delta backscattering intensity indicated that the optimized complex
stabilizer could significantly reduce the thickness of sedimentation layer at the bottom and clarification layer at the top, and
lowered Turbiscan stability index to 1.34. Moreover, the apparent viscosity of sour soymilk was 5.35 mPa·s. In conclusion,
the optimized complex stabilizer can stabilize sour soymilk significantly. This study may provide experimental data to
develop sour soymilk with good stability.

Key words: sour soymilk, pectin, CMC, response surface methodology, particle size, stability index