MOLD GROWTH AND CONIDIATION IN CEREAL-GRAINS AS AFFECTED BY WATER ACTIVITY AND TEMPERATURE

The effects of different water activities (a(w)) and temperatures on g rowth of storage moulds (Aspergillus candidus and Penicillium implicat um) on maize and paddy rice grains were measured using ergosterol cont ent and dilution plating. The results showed that the mode of fungal g rowth depends on a(w). In all cases, conidiation occurred more readily at low a(w), whereas mycelial growth is more marked at higher a(w). T he xerotolerant, thermophilic characteristics of A. candidus were more clearly revealed by the ergosterol content, which reflected mycelial development, than by enumeration of spores formed. The ergosterol cont ent proved to be a better index of technological quality of cereals (a ssessed by acidity) than the number of fungal propagules. A 10-fold in crease in the number of spores corresponded to a doubling of the ergos terol content.