Improvement of physicochemical and probiotic properties of frozen yoghurt by incorporating inulin and guar gum

Özet

Frozen yoghurt is considered as a healthy alternative for ice cream due to its probiotic properties. Inulin and guar gum are well known soluble dietary fibers used as gelling and stabilizing agents in food processing along with their prebiotic properties. However, not that much of investigations have been performed to evaluate their applications in frozen yogurts, particularly their   combination effect on physicochemical, probiotic and sensory properties of frozen yogurts.   Individual  (2.7% inulin and 0.3% guar gum) and combined (2.7% inulin with 0.3% guar gum) effects of inulin and guar gum  on pH, titratable acidity, melting rate, overrun, survival ability of probiotics and sensory attributes of frozen yoghurt were investigated in freezing (-18 ⁰C) storage for a period of 21 days. During the frozen storage, a reduction of pH and an increment of acidity were noticed for all the tested samples. This was more in samples treated with both dietary fibers. The overrun rate was increased in the presence of inulin and guar gum where guar gum had a greater impact.  In freezing storage, probiotic bacteria, Bifidobacterium (BB-12) and Lactobacillus acidophilus (LA-5) showed greater survivability in the presences of inulin and guar gum.  This was more prominenet when both dietary fibers were added.  Frozen yoghurt with combination of soluble dietary fiber (0.3 % guar gum and 2.7 % inulin) had the most appealing sensory characteristics.  It is evident from this study that inulin can be combined with guar gum appropriately to enhance quality attributes of frozen yoghurt including probiotic properties.