Alternaria and Fusarium across malting barley process: a comprehensive study of mycotoxins and quality effects

Abstract

This study aimed to evaluate the incidence and biomass of Alternaria and Fusarium and their mycotoxins during the malting process, as well as their impact on barley grains and malt quality. Barley samples from different geographical regions of Argentina and two genotypes were subjected to micro-malting. Mycotoxins were quantified in grains and subsamples collected at different stages of the malting process using HPLC-MS/MS, while fungal biomass was determined by qPCR. Tenuazonic acid and deoxynivalenol were the main mycotoxins produced. However, alternariol and 15-acetyl-deoxynivalenol were also present in high proportion. The results show low mycotoxin content in the early stages of the process, followed by an increase in later stages, with higher concentrations in malts compared to grains. Alternaria mycotoxins exhibited the highest concentration in malt, while Fusarium mycotoxins were most abundant in the rootlets. Fungal biomass displayed a similar pattern to mycotoxins, increasing as malting progressed, but with a decrease in F. graminearum biomass in malts. The incidence decreased for Alternaria across the malting process but increased for Fusarium in malt, equalling the incidence observed in grains. A negative statistically significant correlation was noted between A. tenuissima sp.-grp. and wort extract. Moreover, significant positivecorrelations were identified between both protein percentage and soluble protein and tenuazonic acid and alternariol. B-hordein was the hordein fraction with higher degradation in malt and with a high negative association with fungal biomass and incidence in grains. These findings are particularly relevantgiven the high mycotoxin concentrations detected in malt, surpassing the legislative limits or indicative values established for grains.