Optimization of probiotic yogurt production containing Zedo gum

A Box-Behnken design (statistical design) was applied to optimize the survival of Lactobacillus acidophilus and Bifidobacterium bifidum in bio-yogurt containing a new exudative Zedo gum. The effect of incubation temperature, storage time, Zedo gum concentration and probiotic inoculation load on probiotics survival, viscosity, acetaldehyde content and other quality indices of yogurt were explored. With respect to probiotics survival, probiotic inoculation load was found to be the most important factor followed by storage time. Zedo gum didn’t show significant effect on probiotics survival (α≥0.05). Viscosity and syneresis of yogurt samples were improved by addition of Zedo gum. Acetaldehyde content, the most potent odorant in yoghurt, was measured using GC-FID. Acetaldehyde content of the samples was not affected by probiotics and Zedo gum but increased by storage time. The optimum conditions of bio-yogurt production were: probiotic inoculation load, 12.24 g/100 kg of milk; incubation temperature, 41.6 °C; storage time; 28.8 days; and Zedo gum concentration, 0.2%. Under such conditions, the predicted Lactobacillus acidophilus, Bifidobacterium bifidum counts, viscosity and acetaldehyde content were 108, 109.6 cfu/g, 3655 cP and 28.2 ppm.