A Transferable Quantitative Framework for Extracting Engineering-Relevant Descriptors from Biological Protective...

Area of Science:

• Biomimetics and Materials Science
• Surface Engineering
• Bio-inspired Design

Background:

• Citrus peel serves as a natural protective layer, offering insights for material science.
• Understanding biological protective surfaces can guide the development of novel engineering materials.
• Existing research lacks a quantitative framework for translating biological surface properties into engineering design principles.

Purpose of the Study:

• To develop a transferable quantitative framework for extracting engineering-relevant descriptors from biological protective surfaces.
• To use these descriptors as design templates for creating biomimetic counterparts.
• To investigate citrus peel as a model for natural protective surfaces.

Main Methods:

• Mechanical testing (cutting, puncture, compression) and gravimetric analysis of peel density and thickness.
• Scanning Electron Microscopy (SEM) at magnifications from 100× to 10,000×.
• Automated image processing pipeline including scale-bar detection, segmentation, and Grey-Level Co-occurrence Matrix (GLCM) texture analysis.

Main Results:

• Principal Component Analysis effectively separated flavedo and albedo regions across all magnifications.
• Grapefruit exhibited the densest cell-bounded surface segment (CBSS) and highest oil-gland density.
• Bitter orange had the largest CBSS area and thickest peel; mandarin showed the most oriented flavedo film; lemon displayed the most open albedo.

Conclusions:

• Citrus peel's structure provides a layered descriptor space: dense surface relief and thick cellular bulk.
• These metrics offer distinct bioinspired design priors: surface films for selective-permeability membranes and cellular cores for impact-absorbing panels.
• A modified-atmosphere packaging (MAP)-compatible biomimetic film is proposed, requiring further gas-permeability verification.