Tailoring polyhydroxybutyrate by molecular weight regulation: Green synthesis, food-grade performance and innovative ketogenic applications.

Polyhydroxybutyrate (PHB) is a biodegradable polyester produced by microorganisms. Precise regulation of its molecular weight (Mw) and molecular weight distribution (MWD) is the core breakthrough for achieving high-value and scenario-based applications of PHB in the food industry. Based on critical analysis, this paper systematically discusses the advantages, disadvantages, and industrial adaptability of three core technologies for precise PHB Mw regulation: biosynthesis regulation, chemical/enzymatic modification regulation, and AI-assisted synthetic biology modification. This study investigates the comparative mechanical properties, degradability, food safety and cost-effectiveness of PHB and other mainstream biodegradable materials, including polylactic acid (PLA) and polybutylene succinate (PBS). The study identifies the distinct competitive advantages of PHB in applications such as high-barrier packaging, edible films and gut-targeted functional carriers. The paper focuses on the advantages, existing bottlenecks and proposed solutions for PHB with different Mw gradients in food packaging, eco-friendly processing aids, food preservation, functional carriers and ketogenic functional foods, highlighting their application advantages, existing bottlenecks and proposed solutions. It emphasised key elements for industrial implementation, including low-cost production processes, compatibility with food industry equipment, and food-grade safety standards and quality control systems. Finally, the paper examined emerging trends in the field, including AI-assisted precision regulation, smart food packaging and precision nutrition delivery systems. The present paper establishes a comprehensive logical framework comprising "technology comparison, application bottlenecks, solutions and future trends". This provides both theoretical guidance and technical support for the standardised and large-scale application of PHB in the food industry, thereby driving the sector's transition towards green and sustainable practices.