Fumonisin occurrence in wheat and wheat by products

CENDOYA E.; NICHEA M.J.; MONGE, MARÍA DEL PILAR; CHIACCHIERA S.M.; RAMIREZ M.L.

Freising

Conferencia; International Commission on Food Mycology Conference 2019 Food- and Airborne Fungi ? Challenges for Food Safety and Supply; 2019

International Commission on Food Mycology

Wheat is the most important cereal consumed by the Argentine population. It can be milled to produce flour and semolina mostly used for bread, pasta or other bakery products elaboration. It is remarkable that wheat flour consumption per capita in Argentina was estimated at 86 kg/habitant/year in 2016. The main pathogen associated with Fusarium Head Blight (FHB) wheat disease in common and durum wheat in Argentina is Fusarium graminearum, also deoxynivalenol (DON) has been reported in both types of wheat. However, when F. graminearum was not the main specie isolated from wheat, the predominant Fusarium sp. was F. proliferatum, and durum wheat grains were contaminated with fumonisins (FBs). Fumonisins are toxic fungal metabolites that have been epidemiologically associated with esophageal cancer and neural tube defects in some human populations. A survey was carried out to determine FBs contamination in 135 common and 40 durum wheat samples in the main wheat production area of Argentina using HPLC-MS/MS. Also, FBs occurrence was analyzed in 46 wheat-based products obtained from local supermarkets. Considering that F. proliferatum could be the responsible for fumonisin presence in wheat and wheat-based products, two ecophysiological surveys were made using srains isolated from wheat, grown in a wheat based-media and in irradiated wheat grains. Moreover, relative FUM8 and FUM19 genes expression was analyzed under different aW and temperature using a wheat-based media. As a result 93% of total wheat grains samples showed FBs contamination, with levels ranging from 0.15 to 1304.39 ng/g, being FB1 the fumonisin most frequently found. Most samples were contaminated with FB1 and FB2. Four and 9 common and durum wheat samples, respectively, showed no contamination with fumonisins, while 9% and 7.5% of common and durum wheat samples, respectively, showed levels higher than 1000 ng/g. All wheat-based products were contaminated with FBs (levels ranging from 0.04 to 18.94 ng/g, median: 1.43 ng/g). A large number of samples had higher levels of FB2 than FB1. Optimal aW levels for F. proliferatum strains growth rate ranged from 0.995 to 0.96 at 25?30 °C, when aW was lower than 0.90 strains were not able to grown. The máximum amounts of FBs were obtained at higher levels of aW (0.995, 0.99 and 0.98) and 25 or 15 °C depending on the substrate and the strain. FB production profiles for each particular strain were related to incubation temperaturas. FUM genes expression at 25 °C correlated with FBs production, regardless the aw, while at 15 °C FBs production was lower than at 25 ºC, but FUM genes were expressed as at 25 °C. This is the first report on natural FBs presence in common wheat grains and wheat-based products in Argentina. Also, the present study provide very useful guidelines for facilitating effective management of predicting risk for growth and mycotoxin production during ripening, harvesting and storage of wheat.