Original Article | 2009, Vol.31, No.5, pp. 481-490
Optimization of prebiotics in soybean milk using mixture experiments
Phakkhateema Sugkhaphan and Kongkarn Kijroongrojana
pp. 481 - 490
Abstract
A mixture experiment was used to optimize prebiotic mixtures in soybean milk formulation. Inulin (I), galactooligosaccharides (GOS), and isomalto-oligosaccharides (IMO) were the prebiotic ingredients added (4% w/v) to soybean milk. Thirteen formulations of soybean milk were compared using the general descriptive analysis and the growth of probiotics (Bifidobacterium bifidum DSM 20456, Lactobacillus plantarum TISTR 875, and Lactobacillus acidophilus TISTR 1034). There were no significant differences (p>0.05) in all sensory attributes (color, thickness, beany flavor, sweetness, viscosity, sweetness aftertaste) among the samples. Various mixtures of the prebiotics had only a slight effect on the soybean milk color and viscosity (p<0.05). The best formulation was determined by the highest growth of the probiotic bacteria. GOS was the prebiotic that stimulated the highest growth in all probiotic strains as shown by its highest growth coefficient. The optimized formulation (0.11I + 0.62GOS + 0.27IMO), after fermentation with the probiotics, stimulated the growth of B. bifidum DSM 20456 from 6.58 to 7.54 log10 CFU/ml (after 48 hrs), L. plantarum TISTR 875 from 6.59 to 8.65 log10 CFU/ ml (after 24 hrs), and L. acidophilus TISTR 1034 from 6.83 to 8.44 log10 CFU/ml (after 24 hrs) and was not different when compared with glucose (p>0.05). The soybean milk supplemented with the optimized prebiotic mixture had higher (p<0.05) carbohydrates, total soluble solid, total solid content, and viscosity than the control (without prebiotic). However, it had a lower L* value (lightness) and a higher a* value (redness) than the control (p<0.05).
