Effect of psyllium husk powder on the viability of Lactobacillus casei in Doogh

The seed husk of psyllium (Plantago ovate Forsk) has a long history of use as a dietary fiber supplement and in traditional herbal medicine, it has been used for treating various disorders. It has an important role in lowering blood cholesterol and has potential to stimulate bacterial growth in digestive system. Therefore, in the present study psyllium husk powder (PHP) at amount of 0, 0.25, 0.5 and 0.75% was added to Doogh samples and its influence on viability of probiotic bacteria Lactobacillus casei was investigated. In addition, the amount of serum separation, pH and sensory properties of this product were studied. Results showed that in the presence of husk powder the growth of Lactobacillus casei has been increased insignificantly. The pH values of the all Doogh samples reduced during 14 days of storage but psyllium husk did not affect the pH even at 0.75% concentration. The addition of PHP increased the consistency, resulted in a reduction in the rate of phase separation. Sensory evaluation revealed that the sample containing 0.25% psyllium powder had more acceptability than others. According to the results, addition of PHP at amount of 0.25% in the presence of probiotic bacteria Lactobacillus casei for production functional Doogh product is recommended.