The increase in fumonisin content in maize after drying was signalled by farmers and it was recently reported also in scientific papers. Because of the mandatory application of drying for a safe post-harvest management of maize, the physico-chemical effects on kernels and their fumonisin content need to be investigated. 6 maize hybrids collected in 2010 in Northern Italy were dried applying 2 different temperature X time combinations: 70°C x 24 hours and 95°Cx 9 hours. Fungal incidence, kernel chemical composition (proteins, fat content, starch) and free and hidden forms of fumonisins (FBs) were investigated pre- and post-drying treatments. Fungal incidence was significantly reduced after thermal application and water activity decrease; both combinations of “temperature x time” treatments were able to reduce more than 85% Fusarium spp. incidence, irrespective of hybrid considered. The dominant variation observed in fumonisin content in different hybrids was an increase, mainly in the free forms, therefore confirming farmers claims, with few exceptions. Regarding chemical composition, fat content decreased 26% and 14% after grain exposure to 70°C x 24 hours and 95°C x 9 hours, respectively. Proteins and starch content resulted unvaried, but a possible retrogradation of starch, and in particular in amylose, has been supposed upon heating. This speculation was based on the analytical results obtained applying 2 different analytical methods that gave comparable results before and significantly different after the drying treatment. The entity of this supposed retrogradation differed between hybrids and the variation of detectable fumonisins after drying is apparently strongly related to these changes in starch structure. Although these are hypothesis and not conclusive remarks, they are very relevant in practice and they confirms the variation in detectable FBs occurring upon drying treatment. The topic needs further investigation to ascertain physic-chemical changes in the matrix composition and their implication in fumonisin detectable amounts, possibly contributing to clarify the masking phenomena.
Giorni, P., Dall'Asta, C., Cirlini, M., Galaverna, G., Battilani, P., Effect of drying treatments on fungal incidence and fumonisin contamination in maize kernels, Abstract de <<World Mycotoxin Forum Conference>>, (Vienna, 10-12 November 2014 ), The World Mycotoxin Forum, Vienna 2014: 148-148 [http://hdl.handle.net/10807/61987]
Effect of drying treatments on fungal incidence and fumonisin contamination in maize kernels
Giorni, Paola;Battilani, Paola
2014
Abstract
The increase in fumonisin content in maize after drying was signalled by farmers and it was recently reported also in scientific papers. Because of the mandatory application of drying for a safe post-harvest management of maize, the physico-chemical effects on kernels and their fumonisin content need to be investigated. 6 maize hybrids collected in 2010 in Northern Italy were dried applying 2 different temperature X time combinations: 70°C x 24 hours and 95°Cx 9 hours. Fungal incidence, kernel chemical composition (proteins, fat content, starch) and free and hidden forms of fumonisins (FBs) were investigated pre- and post-drying treatments. Fungal incidence was significantly reduced after thermal application and water activity decrease; both combinations of “temperature x time” treatments were able to reduce more than 85% Fusarium spp. incidence, irrespective of hybrid considered. The dominant variation observed in fumonisin content in different hybrids was an increase, mainly in the free forms, therefore confirming farmers claims, with few exceptions. Regarding chemical composition, fat content decreased 26% and 14% after grain exposure to 70°C x 24 hours and 95°C x 9 hours, respectively. Proteins and starch content resulted unvaried, but a possible retrogradation of starch, and in particular in amylose, has been supposed upon heating. This speculation was based on the analytical results obtained applying 2 different analytical methods that gave comparable results before and significantly different after the drying treatment. The entity of this supposed retrogradation differed between hybrids and the variation of detectable fumonisins after drying is apparently strongly related to these changes in starch structure. Although these are hypothesis and not conclusive remarks, they are very relevant in practice and they confirms the variation in detectable FBs occurring upon drying treatment. The topic needs further investigation to ascertain physic-chemical changes in the matrix composition and their implication in fumonisin detectable amounts, possibly contributing to clarify the masking phenomena.
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