Study the Effect of Sugar Beet Fibre on the Rheological and Physicochemical Properties and Viability of Lactobacillus acidophilus LA5 in Probiotic Frozen Yoghurt

Dietary fibres are considered as prebiotic agents which can improve the viability of probiotics in food products during shelf life and causing health benefits. In this study, the effect of sugar beet fibre (0, 0.7, 1.5 and 2%) on rheological, physicochemical and viability of LactobacillusacidophilusLA5 in frozen yoghurt during 60 days at -18°C was investigated. Increasing theamount of sugar beet fibre leaded to increasing consistency coefficient and apparent viscosity values while decreasing flow behavior index of ice cream mixes. The maximum amounts of consistency coefficient (103.9 pa.sn) and apparent viscosity (1.44 pa.s) and minimum amount of flow behavior index (0.5) were associated to the sample containing 2% sugar beet fibre. pH and acidity values of samples with sugar beet fibre obtained in the range of 5.36-5.44 and 0.71-0.74% respectively which had significant differences with the control (5.53 and 0.55%). Melting resistance of the samples increased with increasing the amount of sugar beet fibre and maximum amounts of melting resistance was obtained for the sample containing 2% sugar beet fibre (92% vs. 20.85 for the control). Based on obtained results, increasing fibre content in frozen yoghurt had no significant effect on decreasing the number of Lactobacillus acidophilusLA5 during storage but the maximum final population of this organism was associated to the samples containing higher amount of sugar beet fibre(7.9-8.02 log CFU/g).