Formation of lamellar liquid crystal of spray dried probiotic powder - (May/21/2014 )

Dear all researchers, 

This is the first time I faced problem after spray dried the probiotic culture.

All these while the dried powder of probiotic can be dissolved completely in water, however after I changed the source of milk for probiotic cell culture, powder formed after spray drying was hardly to dissolve and apparent in lamellar liquid crystal. I have compare both type of milk ingredients and find out the recent use of milk contain soy lecithin, other than that everything same. 

Is there anyone can provide me advice on it? 

Thank you. 

Lecithin has very low solubility in water and forms lamellate crystals - so these are probably what you are seeing.  Most forms of Casein are also insoluble, but will form micellar structures in water (e.g. standard milk powder).  You may need some form of surfactant in the milk to get the lecithin to dissolve.