Carbon quantum dots from spent citrus peel for biodegradable antimicrobial pectin food packaging

Overview

This technology converts spent citrus peel—a low-value byproduct generated during industrial pectin production—into functional carbon quantum dots (CQDs), fluorescent carbon-based nanomaterials just 1–10 nm in size. These CQDs are then incorporated into pectin to fabricate biodegradable, antioxidant, and antimicrobial active food packaging films. The approach transforms an underutilized waste side stream into a value-added material while establishing a circular pectin-based packaging platform. The resulting films are designed to extend the shelf life of perishable foods such as raw salmon by inhibiting foodborne pathogens and limiting oxidative spoilage, offering food producers a sustainable alternative to conventional synthetic packaging.

Technical specifications

How it works and key features:

• CQDs are produced via a one-step water-based hydrothermal treatment of citrus biomass, a scalable and environmentally benign synthesis route
• Prior published work with tangerine peel-derived CQDs demonstrated an average particle size of 8.2 nm and strong antimicrobial activity against both diarrheal and emetic Bacillus cereus strains
• At a concentration of 2400 μg/mL, these CQDs significantly inhibited both B. cereus types in packaged tofu and supported shelf-life extension compared with untreated controls
• The current program optimizes CQD synthesis specifically from industrial spent citrus peel feedstock, including feed loading, yield, and batch-to-batch reproducibility
• Optimized CQDs are characterized for physicochemical properties and evaluated for antioxidant and antimicrobial activity before being blended into pectin
• Prototype CQDs/pectin films are fabricated and assessed for key packaging properties (mechanical, barrier, and functional performance)
• Antimicrobial performance and shelf-life extension are validated in raw salmon as a real-world food packaging application
• Scale-up feasibility is tracked throughout the program by monitoring process yield, resource demand, and batch consistency

Technology readiness level

The core CQD synthesis from citrus biomass has been demonstrated in published research, including laboratory validation of antimicrobial activity and shelf-life extension in packaged tofu. The technology is currently at approximately TRL 3–4: the underlying method is proven at laboratory scale, and the current 12-month program advances it toward prototype demonstration by adapting synthesis to industrial spent-peel feedstock, optimizing production parameters, and validating active pectin films in a perishable food application.