Designer Enzymes: Food-System-Oriented Biocatalysts for Mitigating Mycotoxin Contamination and Reducing Postharvest Grain Loss.

Mycotoxin contamination remains a major challenge to food and feed safety, agricultural productivity, and postharvest resource utilization. Although numerous mycotoxin-transforming enzymes have been discovered and increasingly improved through protein engineering, only a limited number have progressed from laboratory characterization to practical food or feed applications. This translational gap arises because catalytic efficiency alone does not address matrix interference, processing stress, scalable production, formulation, degradation-product safety, and application-specific regulatory requirements. This review critically examines the development of enzyme-based detoxification across major mycotoxin classes, including aflatoxins, deoxynivalenol and related trichothecenes, zearalenone, ochratoxin A, and fumonisins, while explicitly distinguishing the deployment requirements of food and feed systems. Building on evidence from natural enzymes, engineered variants, matrix studies, animal evaluations, and commercially advanced systems, we use the term "Designer Enzymes" to describe a literature-derived, deployment-oriented engineering concept in which intended-use conditions are defined before optimization and used to guide molecular, manufacturing, formulation, safety, and regulatory decisions. A five-dimensional framework encompassing Mechanistic Understanding, Predictive Design Integration, Multi-Objective Optimization, Deployment Readiness, and Safety and Regulatory Preparedness is used as a qualitative diagnostic tool to identify translational bottlenecks rather than as a formally validated numerical scoring system. Representative systems targeting ZEN, DON, AFB1, OTA, and fumonisins are compared to illustrate their contrasting trajectories from mechanistic discovery to practical deployment. Structure-guided engineering, AI-assisted mutation prioritization, stability optimization, Design-Build-Test-Learn workflows, synthetic biology, multi-enzyme systems, scalable production, formulation, and existing pilot-scale or commercial translation are further evaluated according to the specific bottlenecks they are intended to address. Overall, this review argues that the future of enzymatic mycotoxin detoxification depends less on maximizing technological complexity than on integrating mechanistic evidence, application-specific performance, manufacturability, degradation-product safety, and regulatory readiness. The Designer Enzyme concept therefore provides a structured roadmap for directing promising detoxification enzymes toward credible, safe, and scalable food and feed applications.