Physicochemical and Sensory properties of Probiotic Sweetened Sudanese Fermented Milk (Roub)

Abstract

This study was conducted at the Department of Dairy Science and Technology, College of Animal Production Science and Technology, Sudan University of Science and Technology to evaluate the effect of adding different levels of probiotic culture on the physicochemical and sensory properties of probiotic Sudanese fermented milk during storage. Six liters of fresh cow’s milk were purchased from dairy farm, College of Animal Production Science and Technology. The milk was pasteurized at 85°Cfor 30min then cooled to 45°C. The pasteurized milk divided into three equal portions. Three treatments were carried out. The first treatment was the control sample in which fermented milk drinks was processed by conventional yoghurt starter culture. In the second and third treatments 75% and 100% of probiotics culture of (L. acidophillus, L.casei and L.rhamnosus) were added respectively. The inoculated milk was incubated in all treatments at 40 °C until coagulation occurred. After that sugar solution added mixing with blender, packed into plastic bottles (250 ml capacity) in triplicates for each treatment. There after samples from different treatments were cooled in refrigeration at temperature (4°C). Chemical composition and sensory evaluation were carried out for the fermented milk samples in all treatments at intervals of 1, 5 and 10 days. The results indicated that significant variations (P<0.05) were observed in the fat%, acidity%, ash%, protein % and pH while total solids % showed no significant difference (P>0.05). However, the storage period had significant differences (P<0.05) on the acidity%, ash%, protein%, and pH while the fat and total solids content were not affected by storage period. The sensory characteristics of the fermented milk samples found to be not affected significantly (P>0.05) by the addition of starter cultures except the texture. The color and flavor affected significantly (P<0.05) by storage period.