At aw 0.96, the surface was the most critical part of
the powder bed, as aw had already decreased during warming-
up, resulting in poor reduction of microbial numbers.
Nevertheless, areas with high remaining aw displayed complete
inactivation, at a detection limit of 1 log10CFU/g.
The natural background flora showed to be more sensible against IR heating: at aw 0.8, a reduction of 1–2 log10CFU/
g was obtained for treatments of 11 and 5 kW/m2, respectively,
whereas at aw 0.96, no microbial survivors were
observed in the paprika.