Impact of Fusarium Head Blight on Wheat Flour Quality: Examination of Protease Activity, Technological Quality and Rheological Properties

Wheat infections caused by Fusarium represent a global agricultural problem that reduces grain yield and negatively impacts wheat’s technological and rheological quality. Although fungal proteases or an increase in endogenous proteases due to Fusarium infection could negatively influence wheat storage proteins and dough performance, little research has been performed on either of these topics. The primary objective of this study was to identify the effect of Fusarium infection on protease activity in 25 wheat cultivars grown in two distinct locations in eastern Croatia. Apart from proteolytic activity, this paper describes the impact of Fusarium head blight (FHB) infection on the technological quality parameters of wheat flour and the dough’s rheological properties. The first treatment consisted of naturally grown, healthy wheat without fungicides, while the second treatment utilized wheat varieties subjected to intense FHB infection. Protein and wet gluten content in wheat grain and flour of uninfected cultivars were heavily influenced by testing location, soil type, and quality. Fusarium infection increased the activity of nonspecific proteases by 43% in flour samples from Osijek and 125% in flour samples from Tovarnik. Estimates of effect size showed that FHB infection had twice as big an effect on protease activity in Tovarnik as in Osijek, and a similar trend was found for dough softening. Moreover, the infection significantly impacted wheat cultivars’ extensograph values, indicating a lower resistance to stretching, extensibility, and total stretching energy in infected flour samples, indicating that dough functionality and volume loss can be attributed to exogenous fungal proteases. Still, the magnitude of the effect varied depending on the growth location and the cultivar’s traits. Multivariate data analysis identified three clusters of wheat cultivars, each with varying degrees of the Fusarium infection’s effects. Some cultivars displayed consistent protease activity and flour quality across sites. In contrast, others showed variability in their responses due to environmental conditions. To conclude, genetic resistance could provide adequate control of FHB, guaranteeing the successful protection of wheat quality. However, the possibility of confounding factors influencing genetic and cultivation conditions must be considered, and further research is needed to understand their interaction.