---

The effect of apple and wheat fibers was studied on viability of Lactobacillus acidophilus in symbiotic yogurt and its physicochemical, sensory and rheological properties during 29 days storage at 5±1 ^ºC. The results of analysis showed that the number of Lactobacillus acidophilus in control and sample containing 0.5% fiber were reduced by 1 and 0.5 log cycle respectively and reached to 6 and 6.85 log cycle respectively at the end of storage period. But the sample containing 1% of fiber showed 0.25 log cycle increase in the number of Lactobacillus acidophilus at the same time and reached to 7.6 log cycle. This increase was higher in samples containing wheat fiber in comparison with those containing apple fiber (p<0.05). The samples containing fiber showed higher viscosity and lower syneresis in comparison with those not containing any fiber. The effect of wheat fiber on viscosity was higher than the effect of apple fiber (p<0.05). Increasing the amount of both fibers also caused samples to gain lower score for their color and taste. This decrease was obvious in samples containing apple fiber. Totally the samples containing 0.5% wheat fiber where known as best color and taste point of view between samples containing fiber. So it was concluded that using wheat fiber at the rate of 0.5% not only improved texture and chemical properties of yogurt but it could also provide the consumer satisfaction.  

---

In this study the effect of grape fiber and chitosan on Lactobacillus Fermentum viability, physicochemical and sensorial properties in yoghurt containing kiwi was investigated during storage, using response surface methodology (RSM). Amounts of grape fiber, chitosan and storage time were in the range of 0-1.2 %, 0-1 % and 3-21 day, respectively. The results indicated that with increasing the amount of chitosan, Lactobacillus Fermentum viability decreased, but it was increased by increasing grape fiber during storage significantly (P<0.05). Moisture and syneresis of samples reduced significantly by increasing the amounts of chitosan and fiber (P<0.05). According to sensory evaluation, increasing the amounts of chitosan caused decrease in color scores. Flavor scores decreased as grape fiber increased significantly (P<0.05). In conclusion, using 0.9 % grape fiber, 0.1 % chitosan, and 12 day storage were found as optimum conditions for producing probiotic kiwi fruit yogurt.