Leucaena Leucocephala Gum Exudate: A Novel Natural Stabilizer for Enhancing the Physical Stability of Acidified Milk-Orange Juice Beverages

The growing consumer demand for natural, clean-label food ingredients has intensified the search for novel, sustainable hydrocolloids. This study comprehensively characterizes the exudate gum from Leucaena leucocephala and investigates its efficacy as a stabilizer in the technologically challenging system of acidified dairy beverages. Gum was collected from three distinct agro-ecological regions in Zimbabwe, purified via aqueous extraction and ethanol precipitation, and subjected to extensive physicochemical, functional, and rheological analysis. The purified gum was identified as a high-purity (90-94% carbohydrates), acidic (pH 4.5-4.7) polysaccharide with low protein (2.2-3.0%) and fat (<0.4%) content. Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of carboxylate groups and a typical polysaccharide profile. Rheological assessment revealed concentration-dependent viscosity and pronounced shear-thinning behavior, indicative of a structure-breaking network under shear, a desirable property for beverage stabilization. In a milk-orange juice model system, the incorporation of L. leucocephala gum at a 0.2% (w/w) concentration resulted in a statistically significant (p < 0.05) reduction in sedimentation rate, enhancing physical stability over a 14-day refrigerated storage period compared to the unstabilized control. Critically, sensory evaluation using a 9-point hedonic scale demonstrated that the gum at optimal concentrations (0.1-0.2%) imparted no detrimental effects on color, aroma, taste, or mouthfeel, with overall acceptability scores statistically equivalent to the control. These findings posit L. leucocephala gum exudate as a highly promising, natural, and effective stabilizer for clean-label acidified dairy beverages, offering a viable value-added application for a renewable and underutilized biological resource.