Stabilization mechanisms of suberin dispersions using amphiphilic galactoglucomannans

Food and consumer packaging relies heavily on fossil-derived polymers to provide moisture, oxygen, and grease barriers. However, their non-renewability and limited degradability motivate the development of sustainable alternatives. Suberin is a promising renewable barrier material due to its hydrophobic and crosslinked structure, but its poor dispersibility in water limits its application in aqueous formulations. Here, functionalized galactoglucomannans (GGM) were developed as amphiphilic macromolecular stabilizers for suberin dispersions. GGM was esterified with 1,1'‑carbonyldiimidazole-activated fatty acids to produce derivatives with three alkyl chain lengths (C9, C14, and C18) and three targeted degrees of substitution (0.05, 0.15, and 0.30). Surface tension measurements showed that GGM-C9 at 1% exhibited the highest surface activity, reducing surface tension to 37.5 mN/m compared with 50.0 mN/m for GGM-C14 and 56.9 mN/m for GGM-C18. All formulations exhibited shear-thinning behavior, with viscosity at 1 s^-1 ranging from 951 mPa·s for GGM-C9-L to 3778 mPa·s for GGM-C18-H. Turbiscan analysis showed that optimized melt dispersions achieved Turbiscan Stability Index values of approximately 1 after 4 days, indicating high colloidal stability. These findings demonstrate that GGM-fatty acid derivatives provide tunable interfacial activity, shear-thinning flow behavior, and long-term stabilization of suberin dispersions, highlighting their potential as bio-based stabilizers for sustainable packaging coatings.