The effect of storage temperature and water activity on aflatoxin B1 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 (aw ) (0.85, 0.90, 0.95 and 0.99) on aflatoxin B1 (AFB1 ) production by A. flavus isolate inoculated on hull-less and hulled spelt grains were investigated. RESULTS: The optimal conditions for AFB1 biosynthesis were reached at 30 °C and aw value of 0.99 in the all tested samples (hull-less grains, dehulled spelt grains and hulls). The AFB1 accumulation was significantly higher in hull-less than in dehulled grains, that implicated a protective effect of spelt hulls. The levels of AFB1 were about 10-170 times higher in hulls than in grains. In order to determine the possibility of predicting the occurrence of AFB1 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 AFB1 contamination of stored spelt-based food. The knowledge of the storage temperature and aw effects on the AFB1 content in spelt during the postharvest phase is of great practical importance. © 2019 Society of Chemical Industry.

The protective effect of hulls on the occurrence of Alternaria mycotoxins in spelt wheat.

BACKGROUND: Since there is an increasing demand on the world market for alternative crops suitable for organic production, spelt wheat (Triticum aestivum spp. spelta L.) is a highly attractive farming option. Alternaria species are widespread and infect a great variety of economically important crops. Certain species are known producers of mycotoxins. The aim of this study was to assess the protective effect of hulls covering the spelt kernels on Alternaria toxins. RESULTS: Alternariol (AOH) and alternariol monomethyl ether (AME) were evaluated in hulls and dehulled kernels after plant inoculation with one A. alternata and two different A. tenuissima isolates. Mycotoxins were determinated using high-performance liquid chromatography with dioade array detection. The detected levels of AOH and AME were four times higher in hulls compared to kernels in inoculation treatments. AOH was registered at levels ranging from 227 to 331 µg kg(-1) in dehulled kernels and from 433 up to 1647 µg kg(-1) in hulls. AME was predominant toxin detected in the range of 277 to 398 µg kg(-1) in dehulled kernels and from 1844 to 2183 µg kg(-1) in hulls, with highly significant difference to water control treatment. CONCLUSION: Obtained results indicate the significantly higher concentrations of Alternaria toxins in hulls than in dehulled kernels which implicate the possible protective effect of spelt wheat hulls.