Wheat Fusarium Protease Specificity and Effect on Dough Properties

Area of Science:

• Agricultural Science
• Food Science
• Plant Pathology

Background:

• Fusarium infection poses a global threat to agriculture, impacting grain quality beyond deoxynivalenol (DON) production.
• Fusarium species produce proteases that degrade starch and protein, compromising wheat processing and gluten functionality.
• Canada Western Red Spring (CWRS) wheat quality is particularly susceptible to protease-induced damage, affecting its end-use performance.

Purpose of the Study:

• To assess the impact of Fusarium protease on the functionality of CWRS wheat.
• To quantify protease activity in Fusarium-damaged kernels (FDK) and its effect on wheat dough properties.
• To evaluate the adequacy of current Canadian wheat grading standards in addressing protease-related quality degradation.

Main Methods:

• Spiking FDK-free base wheat with FDK to create samples with varying levels of Fusarium infection.
• Analyzing protease activity in flour extracts using beta-casein digestion assays.
• Conducting extensigraph tests to measure dough resistance and extensibility.
• Performing baking tests to assess loaf volume and dough stability.

Main Results:

• Elevated beta-casein cleavage was observed in FDK-spiked flour extracts, indicating significant protease activity.
• Fusarium protease activity was inversely related to dough resistance (Rmax), with higher protease levels reducing gluten strength.
• Baking tests showed that even low levels of FDK (3%) could lead to loaf collapse, despite similar initial loaf volumes.
• The extent and severity of Fusarium infection directly correlated with protease damage.

Conclusions:

• Fusarium protease significantly impairs wheat dough functionality and baking performance, independent of DON levels.
• Current Canadian wheat grading tolerances for FDK may not fully mitigate protease-induced damage.
• Consideration of non-DON-producing Fusarium strains is crucial for maintaining wheat quality and protecting functionality in grading systems.