Argon cold plasma treatment induces structural and physicochemical modifications of guar gum for enhanced functional...

Argon cold plasma (ACP) treatment is an eco-friendly approach to modify guar gum (GG), a plant-derived polysaccharide with significant food industry applications. This study investigated the impact of ACP treatment (10 W, 2-8 min) on GG's structural, physicochemical, and functional properties. ACP treatment decreased the molecular weight (Mw) with increased treatment time, from 2.82 × 10⁵ (GG) to 1.64 × 10⁵ Da, after 8 min, attributed to reactive plasma species cleaving glycosidic bonds. The mannose/galactose (M/G) ratio peaked at 2.55 after 4 min, attributed to main-chain degradation, but decreased with prolonged treatment, resulting from side-chain disruption. Structural analyses confirmed the preservation of GG's core chemical structure, and revealed increased surface roughness, increased porosity, and reduced aggregation. Thermal stability improved and solubility increased, which correlate with a lower average Mw and enhanced hydrogen bonding. Rheological tests showed shear-thinning behavior and reduced apparent viscosity, consistent with molecular chain depolymerization. Notably, ACP-treated GG had enhanced emulsifying capacity and stability in soy protein isolate (SPI) emulsions, attributed to improved interfacial adsorption and a narrower oil droplet distribution. These findings demonstrate that ACP treatment effectively modifies the physicochemical properties of GG, thereby positioning it as a promising functional enhancer for food emulsification.