13.6   Risk factor Self-heating/Spontaneous combustion
13.6.1 Hydrolytic/enzymatic fat cleavage
13.6.2 Oxidative fat cleavage due to action of oxygen
13.6.3 Loss prevention measures
Fat- and oil-containing hygroscopic solids of organic origin with a low water content (WCC 2) and 2nd or 3rd order biotic activity (BA 2 or BA 3) have a tendency to undergo self-heating due to chemical, physical and biotic decomposition processes.
Self-heating describes the increase in temperature within an organic solid which, even in the absence of an ignition source, may result in spontaneous combustion, which occurs once the material's specific autoignition temperature has been reached without external heat input. Such goods include oil-bearing seeds/fruits and nuts (BA 2), feedstuffs of vegetable origin, e.g. pellets, fibers/fibrous materials, and feedstuffs of animal origin, e.g. fish meal (BA 3).
Causes and promoting factors of self-heating are primarily the goods' high oil content, as well as moisture, oxygen, high molecular weight, high fiber content, grain size and maturing time. Sunflower seeds, peanuts, babassu kernels, almonds, Brazil nuts, hazelnuts, walnuts, pistachio kernels and copra exhibit particularly high oil contents of > 50% (see Section 17.2).

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