∑ the temperature of the grainaround 40 ÎC;
∑ insectsare present.
In this case,the controlmeasures are chemical,suchas fumigation.
Wet-grain heatingis causedby microflora and is characterized by:
∑ the moisturecontent of grainhigherthanthe critical moisture;
∑ the temperature is higherthan40 ÎC and it can reach to 60 ÎC;
∑ no insects are present.
In this caseaeration is recommended, to lowerthe humidity and temperatureof
the commodity.
Chemical heatingis the continuation of the biological heatingand is caused
by the oxidationof the unsaturated fats. In this process,the heatproduced can
reachover100 ÎC, in somecasesup to 300 ÎC, whichmakesit possible that the
commodity will ignite.
Fig. 26.2 Moisturemigrationin storedgrainas a resultof hot-spotformationcausedby
insects.
Improvingthe control of insects in foodprocessing 413