Abstract: A process for reducing viable microbial content of a substantially solid material which is susceptible to microbial spoilage or contamination, the process comprising: (a) entraining a biocidal substance in a carrier gas to form a biocidal gas mixture by adding a biocidal substance to a heated carrier gas; and (b) contacting exposed surfaces of the solid material with the biocidal gas mixture heated to an elevated temperature of at least about 10° C. above the dew point of the biocidal gas mixture for a sufficient period of time so that at least some microbes on the exposed surfaces are exposed to the biocidal substance in the biocidal gas mixture.