Spray-drying microencapsulation of citral with soy protein-soy polysaccharide Maillard reaction products: stability and release characteristics

Soy polysaccharide is a new source of hydrocolloids that demonstrated some unique functions, such as improving the emulsifying property of proteins. Citral is an essential oil that shows promise as an alternative to antibiotics for livestock such as chickens. However, lack of effective delivery methods has limited its application in livestock production. The objectives of this study were to develop and characterize, in vitro and in vivo, a citral product encapsulated with a soy protein-soy polysaccharide Maillard reaction product (SPPMP) through spray drying technology. During initial formulation screenings, SPPMP significantly outperformed the physical mixture of soy protein and soy polysaccharide (SPP). A formulation comprising 10.4% SPPMP and 13% citral was selected for further evaluation. When tested in the simulated gastrointestinal system, the SPPMP-microparticles retained over 75% of citral after the gastric phase and released the citral completely during the intestinal phase. The release of citral from the SPPMP- and SPP-microparticles in the simulated gastrointestinal system followed the zero-order kinetics at the early phase (0–180 min), and a first order non-linear BoxLucasl kinetics at the later phase (>180 min). The release kinetic parameters were significantly better for SPPMP-microparticles compared to SPP-microparticles (p < 0.05). When tested in vivo, a threefold increase in citral concertation was detected in the intestinal digesta obtained from chickens fed with SPPMP-microparticles compared to chickens fed with non-encapsulated citral. Good long-term stability of citral in SPPMP-microparticles was observed. The current study demonstrates that SPPMP is a suitable encapsulation wall material for intestinal delivery of citral and potentially other similar hydrophobic compounds.