Storage stability of spray-dried yoghurt powder

Yoghurt powder spray-dried at the optimum conditions previously determined (outlet air temperature of 60.5 degrees C, inlet air temperature of 171 degrees C, feed temperature of 15 degrees C) was packaged in glass jars and aluminium laminated polyethylene (ALPE) pouches and stored at 25 degrees C and 50% RH for 90 days. The storage stability of yoghurt powder in terms of quality parameters (moisture content, water activity, titratable acidity, pH, colour change, thiobarbutyric acid (TEIA) value, Streptococcus thermophilus and Lactobacillus bulgaricus counts, total yeast and mould counts, overall sensory acceptability) was studied. Moisture content, water activity (a(w)), TBA value increased, whereas Str. thermophilus and Lb. bulgaricus counts decreased during storage. Change in colour and overall sensory acceptability of powder was affected by storage time.