Functional Plant Substrates in Sourdough Fermentation: Hops, Kombucha, and Grape Pomace

Sourdough fermentation represents a cornerstone of traditional and modern baking, offering enhanced flavour, texture, and nutritional benefits. With the increasing demand for sustainable and functional food products, plant-derived substrates have emerged as transformative tools in artisanal and industrial bread production. These ingredients address critical challenges such as microbial stability, shelf life, and sensory quality while contributing unique biofunctional properties like antioxidant activity and antimicrobial effects. Despite their promise, challenges such as bitterness from hops, phenolic inhibition in grape pomace, and the scalability of kombucha starters underscore the need for precise optimization strategies. Emerging biotechnological approaches, including encapsulation, synthetic biology, and genetic engineering of microbial strains, are explored as solutions to maximize the efficiency and consistency of these substrates. This review provides a roadmap for integrating plant-derived fermentation substrates into sustainable baking practices, with implications for meeting consumer preferences and advancing functional food innovation.