Effects of temperature, water activity, and fungal isolate on ochratoxin A accumulation in oat grain inoculated with Penicillium verrucosum and development of a methodology to screen oat cultivars for ochratoxin A accumulation

Abstract

AbstractBackground and objectivesOchratoxin A (OTA) is one of the most prevalent mycotoxins in cereal grains. In temperate climates, Penicillium verrucosum is the primary OTA producer. Our objectives were (a) to determine the effects of various factors on OTA accumulation in oat grain inoculated with P. verrucosum and (b) to develop a method to screen oat cultivars for OTA accumulation.FindingsGrain samples from three oat cultivars were inoculated with three different isolates of P. verrucosum, incubated at two water activity levels (0.85 and 0.90 aw) and two temperatures (22.5 and 27.5°C) for 4, 7, and 10 weeks. A water activity of 0.90 and a temperature of 22.5°C provided the highest level of OTA accumulation. Isolate C1136‐1 was the highest OTA producer among the isolates of P. verrucosum studied. The longer the incubation period, the higher the OTA accumulation in oat grain samples was.ConclusionsThe P. verrucosum isolate, the water activity and temperature during incubation, and the incubation period, all had an effect on the level of OTA accumulation. Inoculating grains with isolate C84‐2 and incubating at 22.5°C and 0.90 aw for 7 weeks provided adequate conditions to screen oat cultivars for OTA accumulation.Significance and noveltyA new protocol was developed that can be used for discriminating among oat cultivars for level of OTA accumulation. It would ultimately help breeders and pathologists in selecting genotypes with reduced OTA accumulation.