Effect of High‐Intensity Ultrasound on Structural and Functional Properties of Buttermilk and Its Application in Ice Cream

Buttermilk, a by‐product of butter manufacturing, is rich in proteins and milk fat globule membrane (MFGM) components with valuable techno‐functional properties; however, it remains underutilized in the dairy industry. This study investigated the impact of high‐intensity ultrasound (HIUS, 20 kHz) on the structural and functional properties of buttermilk and evaluated its application in ice cream formulation. Buttermilk solutions were subjected to HIUS at different amplitudes (20%, 40%, and 60%) and durations (5, 10, and 15 min). Protein structural changes were characterized by free sulfhydryl content and Fourier transform infrared (FTIR), while functional properties, including solubility, viscosity, fat absorption capacity (FAC), and emulsifying indices, were assessed. Moderate HIUS treatments (20‐5, 20‐10, 20‐15, and 40‐5) significantly increased thiol exposure ( p < 0.05), whereas more intense conditions appear to promote protein association. However, most functional properties showed no significant differences with the control; the only exception was FAC, which showed significant improvement in almost all cases ( p < 0.05). Accordingly, FTIR spectra confirmed rearrangements in protein secondary structure and enhanced protein–lipid and protein–lactose interactions. Compared to the control and a sample with nonsonicated buttermilk, the ice cream with HIUS‐treated buttermilk (20% amplitude for 5 min) exhibited lower overrun (~8%) and improved meltdown resistance, attributed to its denser and compact microstructure by confocal microscopy. Sensory evaluations showed that all three ice cream formulations received favorable ratings and no significant differences among them, on the 9‐point hedonic and labeled affective magnitude (LAM) scales. However, the HIUS‐treated buttermilk ice cream showed slightly lower scores, mainly for texture and overall liking, which may be associated with ultrasound‐induced changes and reduced air stabilization capacity. Overall, under the conditions studied, HIUS treatment enhances specific functionalities of buttermilk and demonstrates potential for improving frozen dairy products. Optimization of ultrasound parameters and HIUS‐treated buttermilk doses is recommended to maximize functional benefits while minimizing negative effects on product quality and consumer acceptance.