Effect of moisture on wheat grains lipid patterns and infection with Fusarium graminearum

LEONEL MAXIMILIANO ORTEGA; LILIAN ROMERO; CANDELA MOURE; GABRIELA GARMENDIA; DIANA RAMÍREZ ALBUQUERQUE; VIRGINIA FERNÁNDEZ PINTO; SILVANA VERO; ALCONADA TERESA

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 306

0168-1605

Suitable conditions of temperature and humidity are required to maintain wheat grains quality, but duringprocessing and storage, the grains can be exposed to adverse environmental conditions and presence of infectious fungi. Fusarium graminearum, the main causal agent of Fusarium head blight on wheat, affects cropyields and grain quality by alteration of their biochemical components and mycotoxin contamination, whichreduces the possibilities of wheat end use and compromises food safety. Lipid degradation by hydrolytic, oxidative and microbial deterioration is the predominant cause of the loss of sensory acceptability, nutritional valueand baking quality. The aim of this research was to determine the influence of adverse environmental conditions?as the increasing moisture ? on lipid patterns of whole wheat flours contaminated with F. graminearum inrelation to the infection degree. In vitro cultures of F. graminearum were carried out on wheat grains underdifferent degrees of relative humidity (11, 50, 75 and 100%) throughout 45 days of incubation at 28 °C. Thefungal biomass measured by q-PCR increased proportionally with the humidity. A decrease in the signals ofsaturated (palmitic and estearic) and unsaturated (oleic, linoleic and linolenic) fatty acids, analyzed as fatty acidmethyl esters (FAMEs) by GC?MS, was observed in relation with the humidity and infection degree. The degradation rate of the lipids was high during the first 15 days of incubation, reaching the fatty acids content,values around 20?40% of those found in the control. From that moment on, the rate of degradation was sloweror even null. It was observed that in all treatments, the linolenic acid reached the highest degradation ratio incomparison with the other fatty acids, which may be caused by the action of lipoxygenases. The lipase activityand the content of deoxynivalenol were also determinate on the flours. The lipase activity increased until day 25of incubation reaching twice the initial value. The deoxynivalenol content also increased along incubation whilefatty acids decreased. Our results demonstrated that the magnitude in the signal of fatty acids in whole wheatflours varied in relation to the degree of humidity and fungal infection of the grains from which they wereobtained. Otherwise, lipids and their oxidation products are related with the pathogenesis and production ofmycotoxins. These observations highlight the importance of an adequate manipulation of wheat grains on theprocessing chain to prevent quality changes and mycotoxins contamination.