The Germination Paradox in Sorghum: A Review

Sorghum (<i>Sorghum bicolor</i> L. Moench) is a climate-resilient cereal with significant potential as a functional food due to its distinctive polyphenolic profile, including rare 3-deoxyanthocyanidins (3-DXAs). Broader utilisation of sorghum is limited by low protein digestibility and the presence of anti-nutritional factors, such as condensed tannins and phytates. This review consolidates current evidence on germination as a bioprocessing strategy to address these limitations and enhance the bioactivity of sorghum polyphenols. Germination activates endogenous hydrolytic enzymes, such as phytases and esterases, and upregulates the phenylpropanoid pathway through phenylalanine ammonia-lyase, which promotes the release of cell wall-bound phenolic acids and the de novo synthesis of flavonoids. A "germination paradox" is identified, in which qualitative shifts toward lower-molecular-weight, more bioaccessible aglycones enhance antioxidant and anti-inflammatory efficacy, even when total phenolic content fluctuates. The review also examines the effects of germination on digestive release, transepithelial transport, and colonic microbial transformation of phenolics. Finally, genotype- and process-dependent optimisation windows, typically 48-72 h, are delineated to balance anti-nutrient reduction with phytochemical retention, providing a basis for the development of germinated sorghum-based functional foods and nutraceuticals.