Sub-samples (0.1 g) of spray dried capsules of both A17 and B21, collected after spray drying were placed into a series of Eppendorf tubes with rubber septa and tightly closed before storing at 20 C for 8 weeks.
Cell survival was monitored every two weeks by taking two tubes (for each strain), dissolving in peptone water for 20–30 min and serially diluted and plated.
Cell survival was calculated as an average of four readings from two independent experiments and expressed as log CFU g1 for ease of comparison.