2.4.5. Effect of a pre-incubation regime on shelf-life
Due to lower than expected viabilities after a 6-month period at 40 _C in the previous experiment, we decided to test the importance of allowing conidial powders with high initial aw to equilibrate to lower O2/moisture levels within the package before exposure to high temperature regimes. Bb samples were kept over drierite or NaCl for 2 d at 25 _C, resulting in 0.020 ฑ 0.0008 and 0.740 ฑ 0.0018 aws, respectively. Then, conidia were transferred to foil pouches each with one RP-3A O2/H2O absorber sachet and pre-incubated for an additional 5 days at 25 _C (equilibration period) before storage at target temperatures (25, 40, and 50 _C). Alternatively, samples were kept over drierite or NaCl for 7 d at 25 _C, transferred to foil pouches with RP-3A sachets and immediately stored at target temperatures without a 5-d pre-incubation period at 25 _C. Each treatment was replicated four times and
assessment of conidial aw and germinations were carried out after 60 d at 50 _C, and 180 d at either 25 or 40 _C.