Biological control of fungal spoilage in fruit: Mechanisms, microbial interactions, and implications for food quality

Fungal spoilage is a leading cause of postharvest losses in fruit, resulting in quality deterioration, economic losses, and food waste throughout the supply chain. Conventional control using synthetic fungicides faces increasing challenges from resistance development, environmental concerns, and regulatory restrictions. Biological control agents (BCAs) offer a sustainable alternative, but their commercial adoption requires deeper understanding of their mechanisms and reliable integration into postharvest systems. This review synthesizes recent advances in next-generation BCAs, emphasizing the science-based selection of antagonistic yeasts, bacteria, and microbiome-derived isolates. Beyond nutrient and space competition, we examine complementary mechanisms including antibiosis mediated by antimicrobial metabolites and volatile organic compounds, mycoparasitism involving cell wall-degrading enzymes, and host defense priming through jasmonate, salicylate, and ethylene signaling pathways. To address performance variability in commercial settings, we evaluate integrated strategies combining BCAs with physical treatments (heat, UV-C, modified atmospheres), food-grade additives, and advanced formulation technologies such as microencapsulation and nanotechnology-enabled delivery that enhance viability, stress tolerance, and controlled release. Finally, we discuss the need for validation under supply-chain conditions, microbiome-informed design of stable bioactive consortia, and integration of BCAs into a preharvest-to-postharvest management framework. By connecting fundamental microbial mechanisms to practical applications, this review provides a framework for developing sustainable, residue-free strategies to reduce postharvest spoilage and maintain fruit quality.