Typically xerotolerance is used with respect to matrix drying, where a substance has a low water concentration.
Mold growth on bread is an example of food spoilage by xerophilic organisms.
[citation needed] Complete dehydration based on the freeze-drying technique with effective protection inside a tight packaging system, strictly impervious to water and atmospheric gases (O2 and CO2), may be required for long-term preservation of food and pharmacochemical substances (antibiotics, vaccines…).
Freeze drying can limit the microbial activity on the long term, as long as the product remains perfectly dry in a hermetically sealed and intact package, but it is not a sterilisation technique per se, because after rehydration, even if many dehydrated cells suffer irreversible and lethal damages, some resistant spores and bacterial endospores can still be revived again, and multiplied, by means of microbiological cultures if the product was not initially sterilized by applying a proven technique.
Examples of xerophiles include Trichosporonoides nigrescens,[2] Zygosaccharomyces, and cacti.