Mechanistic insights into encapsulation systems enhancing probiotic thermotolerance: A cross-system review

Thermal processing poses significant challenges for maintaining the viability of probiotics in heat-treated foods, such as pasteurized, ultra-high-temperature treated, or baked products. Encapsulation has emerged as a promising strategy to mitigate heat-induced damage, though the mechanisms behind its protective effects remain insufficiently understood. This narrative, critical review examines the mechanisms of thermal injury to probiotics, including membrane destabilization, protein denaturation, water migration, osmotic imbalance, and oxidative stress. It also outlines how encapsulation modulates heat transfer, water mobility, and interfacial stability. The structural features and protective pathways of various encapsulation systems—such as microcapsules, hydrogels, emulsions, conjugates, and composite systems—are synthesized and compared, highlighting differences in thermal behavior and reported protective outcomes. Cross-system comparison identifies restricted water mobility, reinforced matrix and interfacial structures, and potentially altered heat-transfer pathways as recurring features associated with improved thermotolerance. Their effectiveness, however, varies with carrier structure, probiotic strain, and heating regime. Industrial application faces challenges in processing compatibility, scalability, regulatory concerns, and sustainability. Future research directions focus on standardized evaluation methods, multi-omics approaches, predictive modeling, and the development of adaptive, clean-label encapsulation materials. Overall, effective thermo-protection appears to depend on interactions among carrier microstructure, probiotic strain, and processing conditions rather than on material type alone, supporting more rational design of heat-resistant probiotic delivery systems.