The Physicochemical Properties of TEMPO-Mediated Oxidized Xanthan Gum and Their Contribution to the Stability of Acidified Milk Drinks

Acidified milk drinks (AMDs) are susceptible to protein aggregation and phase separation during production and storage, and xanthan gum (XG) is limited in application due to poor compatibility with milk proteins under acidic conditions. This study sought to improve the stabilizing performance of XG in AMDs through TEMPO-mediated oxidation. A series of oxidized xanthan gum (OXG) with different oxidation degrees were prepared by the TEMPO/NaClO/NaBr system, whose physicochemical properties were characterized, and the stabilizing effect and mechanism in AMDs were investigated. The results showed that high-degree OXG significantly improved the stability of AMDs, with the centrifugal sedimentation rate reduced from 8.93% to 2.22% and the zeta potential decreased from -32.6 mV to -37.9 mV, achieving a stabilizing effect comparable to that of sodium carboxymethyl cellulose (CMC). OXG could form uniform protein-polysaccharide aggregates with milk proteins, which may help inhibit phase separation. This study confirms that TEMPO oxidation can directionally regulate the structure and physicochemical properties of XG, enhancing its stabilizing effect in AMDs, which provides a new technical approach and theoretical basis for polysaccharide modification and the stabilization of acidic protein drinks.