Properties and microscopy analysis of encapsulated spray dried grey oyster mushroom (Pleurotus pulmonarius) powder culture from temperature effect

Spray drying technique is a useful innovation for liquid spore culture and an assurance of the powder form of culture can be revived is an important factor of drying. The effect of variuos inlet temperature (80, 90, 100, 110, 120, 130, 140 & 150oC) on encapsulated spores culture of grey oyster was studied and the powder properties (moisture content, water activity, hygroscopicity) were analyzed using two types of protectant materials (10% maltodextrin and 10% of Arabic gum). At 80oC, the highest moisture content obtained were 5.867% and 5.9333% and the lowest value were 3.267% and 3.333% at 150oC with maltodextrin and Arabic gum respectively. Meanwhile, water activity was also reduced from 0.346 to 0.449 for maltodextrin and 0.401 to 0.330 for Arabic gum with an increase of temperature. However hygroscopicity value was increased from 29.886 to 36.170% and from 21.094 to 45.366% for maltodetrin and Arabic gum respectively from the increase of temperature. The scanning electron microscopy images show that significant shrinkage in particles from their spherical shape was observed at temperature above 120oC. This study proved that the powder culture of P. pulmonarius was able to develop and hence there is a potential to be preserved in a longer period.