Xerophilic fungi

The formation of methyl ketones can be rationalized by a modified f-oxidation of fatty acid precursors (18). This process, caused by some moulds, mainly deteriorates short chain fatty acids and leads to the so-called "ketonic-rancidity". Kinderlerer et al. (19-21) demonstrated the formation of methyl ketones and secondary alcohols by some xerophilic fungi isolated from coconuts. After deacylation and decarboxylation of the f-ketoacyl-CoA-intermediates the last step of the biogenetical sequence is the reduction of the corresponding methyl ketones. 

Pitt, J. I. (1975). Xerophilic fungi and the spoilage of foods of plant origin. In "Water Relations of Foods" (R. B. Duckworth, ed.), pp. 273-307. Academic Press, London. 

Hocking, A. D., Pitt, J. I. (1980). Dichloran-glycerol medium for enumeration of xerophilic fungi from low-moisture foods. Applied and Environmental Microbiology, 39,488. 

Storage temperature of food is less important than the presence of moisture, since fungi can grow and produce toxins over a wider span of temperatures than can any other microorganisms. Most species are able to grow at an aw of 0.8 to 0.88 while xerophilic types can grow at an aw of 0,65 to 0.75. A relative humidity of from 70 to 90% establishes suitable moisture equilibrium for initiation of mold growth and toxin formation in numerous food products. See also Activity Coefficient,... 

---