Descriptive Consensus Pathway Analysis Identifies Matrix-Dependent Metabolic Patterns During Wheat-Germ Fermentation

Wheat germ is a nutrient-rich cereal by-product with potential for valorization through fermentation. This study employed 1H NMR metabolomics to characterize the soluble metabolomic profiles of whole soft wheat germ (WWG) and industrially defatted durum wheat germ (DWG), with or without 20% semolina supplementation, fermented using a defined mixed starter culture. Samples were analyzed before fermentation (T0) and after sourdough propagation (TF). Metabolomic data were evaluated through exploratory multivariate analysis, metabolite-level comparisons, and Consensus Pathway Analysis (CPA), a framework integrating metabolite coverage, contrast magnitude, network topology, and reference-framework representation. WWG-based systems exhibited broader fermentation-associated metabolite redistribution than DWG-based systems, particularly involving carbohydrates, organic acids, and fermentation products. CPA highlighted pathway associations related to central carbon metabolism and amino acid- and nitrogen-related processes. Differences between WWG- and DWG-based formulations persisted throughout fermentation, while semolina supplementation was associated with distinct responses in the two wheat-germ matrices, which is consistent with matrix-dependent metabolomic patterns. Because each formulation was represented by a single fermentation experiment, the findings should be regarded as exploratory and hypothesis-generating rather than statistically generalizable. Nevertheless, CPA provided a structured approach for organizing metabolomic observations and identifying candidate biochemical relationships for future investigation. Overall, this proof-of-concept study suggests that wheat-germ matrix characteristics may contribute to shaping fermentation-associated metabolomic profiles and provides a framework for future studies on the biotechnological valorization of wheat-germ processing fractions.