The effect of high methoxyl pectin and gellan including psyllium gel on Doogh stability

The influence of three stabilizers, psyllium seed hydrocolloid (PSH, 0.25% w/w), high methoxyl pectin (HMP, 0.25% w/w), and gellan gum (GG, 0.05% w/w) alone or in a binary mixture, on the phase separation during 21 days of storage, mean particle size and distribution, xi-potential, rheology, microstructure and sensory characteristics of an Iranian fermented milk drink "Doogh" was investigated. Results revealed that the stability of Dooghs prepared with binary combinations of HMP, PSH and GG was significantly higher than samples manufactured with each of these hydrocolloids alone. Use of a binary mixture of PSH and HMP with the lowest instability rate (6.08%) and the highest absolute negative xi-potential (-7.10 mV) led to a desirable effect on the critical sensory attributes. The maximum consistency coefficient under the power-law rheological model (R-2 > 0.97) was found for Dooghs formulated with GG alone. This study provides important data on the performance of different types of polysaccharides, which can be used in formulating acidified milk beverages systems.