Dynamic Deterioration Pattern of Soybean Meal Contaminated by Fusarium graminearum

As a major contaminant fungus in grains and by-products, Fusarium graminearum rapidly colonizes and proliferates, posing safety risks to feed commodities. In this study, artificial inoculation was adopted to simulate F. graminearum contamination in soybean meal. Dynamic changes in fungal population, protein secondary structure, microstructure and volatile organic compounds (VOCs) were systematically monitored across a 54-day storage period. Soybean meal exhibited a three-phase deterioration pattern: latent infection (0–30 d), accelerated spoilage at day 36, and severe deterioration (42–54 d). Fungal conidia counts increased sharply before declining moderately with extended incubation. Ordered protein conformations (α-helix and β-sheet) underwent continuous degradation and converted into disordered β-turn and random coil structures, accompanied by gradual disruption of the compact microstructure of soybean meal. In total, 99 VOCs spanning 13 chemical classes were identified throughout the contamination timeline. Combining orthogonal partial least squares discriminant analysis (OPLS-DA) and Pearson correlation analysis, five volatile biomarkers tightly associated with F. graminearum spoilage were screened: four upregulated fungal metabolites and one downregulated endogenous flavor compound. This work characterizes the dynamic deterioration profiles and volatile fingerprint of F. graminearum-inoculated soybean meal under controlled laboratory conditions, delivering preliminary laboratory evidence to support the future development of potential spoilage monitoring approaches.