The effect of storage temperature and water activity on aflatoxin B accumulation in hull-less and hulled spelt grains.

Background: In concomitance with shifts in climate conditions in recent years, an increasingly frequent emergence of Aspergillus flavus and aflatoxins in cereals has been observed. In this study the effects of temperature (15, 23, 30 and 37 °C) and water activity (a ) (0.85, 0.90, 0.95 and 0.99) on aflatoxin B (AFB ) production by A. flavus isolate inoculated on hull-less and hulled spelt grains were investigated.

Results: The optimal conditions for AFB biosynthesis were reached at 30 °C and a value of 0.99 in the all tested samples (hull-less grains, dehulled spelt grains and hulls). The AFB accumulation was significantly higher in hull-less than in dehulled grains, that implicated a protective effect of spelt hulls. The levels of AFB were about 10-170 times higher in hulls than in grains. In order to determine the possibility of predicting the occurrence of AFB under different storage conditions mathematical models [second order polynomial (SOP) and artificial neural network (ANN)] were applied.

Conclusion: The achievement of such estimation facilitates further decisions on continuous monitoring of the potential hazard related to AFB contamination of stored spelt-based food. The knowledge of the storage temperature and a effects on the AFB content in spelt during the postharvest phase is of great practical importance. © 2019 Society of Chemical Industry.