Condensed tannins as co-wall materials in soybean oil microencapsulation: A strategy for lipid protection

Soybean oil is widely used in ruminant nutrition due to its high energy density and elevated unsaturated fatty acid content; however, its susceptibility to ruminal biohydrogenation and oxidation limits its nutritional efficiency, driving the development of technological strategies to protect lipids. In this context, condensed tannins (CT) have emerged as promising functional components for application in microencapsulated systems. This study evaluated the use of CT as a co-wall material, in combination with gum arabic, whey protein isolate, and soy protein isolate for the spray-drying microencapsulation of soybean oil, with a focus on microstructure modulation and lipid core protection. The microparticles were characterized for microencapsulation efficiency, oxidative stability, antioxidant activity, and morphology. The formulations exhibited high microencapsulation efficiency (84.89–96.67%) and low peroxide values (0.71–1.73 meq O₂/kg), reflecting primary lipid oxidation (hydroperoxides), indicating effective oxidative protection of the oil. Antioxidant activity showed no linear relationship with total phenolic content, suggesting that reactivity is influenced by interactions between CT, proteins, and polysaccharides, which may affect the release of phenolic compounds from the encapsulating matrix. Scanning electron microscopy micrographs revealed predominantly spherical particles and morphological differences consistent with those of the wall composition, supporting CT’s role as a matrix structuring agent. Overall, the results demonstrate that CT incorporation modulates the microstructure and system performance, reinforcing its potential as a co-wall material in lipid microencapsulation systems for ruminant nutrition applications.