EFFECT OF WATER ACTIVITY ON DISAPPEARANCE OF PATULIN AND CITRININ FROM GRAINS

Abstract
Sterile, ground barley, corn and wheat were adjusted to different water activities (aw) and intentionally contaminated with patulin and citrinin. Samples were incubated at 25°C at a relative humidity in equilibrium with their aw. Toxin levels were determined by thin‐layer chromatography (TLC) after different periods of incubation. Disappearance rates were greater in substrates with a higher aw. At aw= 0.70, estimates of half‐lives for patulin in barley, corn, and wheat were 12.7, 4.4 and 4.4 days, respectively; at an aw of 0.90, they were 6.8, 2.4 and 1.9 days. For citrinin, these values were 7.8, 15.5 and 11.9 days at aw= 0.70, and 1.8, 10.4 and 3.0 days at aw= 0.90. Because of these short half‐lives, grains that were responsible for a mycotoxicosis may, at the time of analysis, contain only low levels of these toxins.