Paper Title
Microbiological Quality of Probiotic Frozen Yoghurt Formulated Using Whole and Skimmed Milk and Different Types of Sweeteners

Abstract
The aim of this workwas to study the survival of probioticbacteria in frozen yoghurt formulated with milk having different fat contents (whole milk and skimmed milk) and different types of sweeteners (unrefined cane sugar and longan honey). Three strainsof probiotic bacteria were incorporated in the yoghurt making processing, using the typical yoghurt starters culture Lactobacillus bulgaricus and Streptococcus thermophilus. The probiotic strains included Bifidobacteriumbifidum B4140, Lactobacillus casei subsp. casei B1922, and Leuconostocmesenteroides TISTR473.Survival of probiotic strainswere investigated in the yoghurt and concentrated yoghurt used as a base for frozen yoghurt production, and in the frozen yoghurt stored at -20˚C for 30 days. Using the process and formulation in this study, L. casei subsp. casei B1922 demonstrated the highest viability(1010 CFU g-1) in all treatments (whole milk/skimmed milk, made with cane sugar and honey) of frozen yoghurt products. Bifidobacterium bifidum B4140, L. casei subsp. casei B1922 and L. mesenteroides TISTR473 had average survival percentages of 74.57-92.68, 85.39-96.70, and 87.97-95.92, respectively. The milk types (or the fat contents in the milk) and the types of sweeteners did not seem to have a significant effect on the survival of the probiotic L. casei B1922 and L. mesenteroidesTISTR473, buta possible effect of types of sweeteners on the survival of B. bifidumB4140 was noted (p ˂ 0.05; average survival percentage of 74.57±0.33).Overall, the frozen yoghurt production process using concentrated yoghurt made from either whole milk or skimmed milk and natural sweeteners reported in this study supported the survival and resulted in acceptably high numbers(≥6 log CFU g-1) of these probiotics in the products. The formulae developed in this study could be used as basic formulae for further development of probiotic frozen yoghurt products. Keywords - Functional Food, Frozen Yoghurt, Probiotics