Template-based preparation of W/O/W-type spray-dried probiotic microcapsules using pectin-zein pickering emulsion

Probiotics are vital to human health, yet their viability is susceptible to adverse conditions during food processing, storage, and the digestive process. Currently, spray-dried emulsified microencapsulation technology is widely employed for the preservation of probiotics and the development of related products. Nevertheless, challenges persist, including low encapsulation efficiency, premature release, and low probiotic survival rates. Herein, a water-in-oil-in-water (W/O/W) Pickering emulsion (PE-ZPe) stabilized by pectin-zein complex nanoparticles (PEC-ZNP) was developed as a template for encapsulating Bifidobacterium longum, thereby achieving high survival rates and targeted release. Results from FTIR, XRD, CLSM, and LF-NMR indicated that PEC and ZNP form a more stable outer aqueous interface layer through electrostatic interactions, hydrogen bonding and hydrophobic interactions. The prepared PE-ZPe exhibited excellent storage stability and tolerance to the gastrointestinal environment. The shear-thinning properties of the emulsion enabled it to pass smoothly through the nozzle during spray drying, effectively preventing blockages. Following spray drying, the PE-ZPe microcapsules exhibited a low moisture content, significantly reduced sticking or clumping. Their stable bilayer core-shell structure effectively minimised the logarithmic reduction in Bifidobacterium longum. Results from storage and simulated gastrointestinal experiments indicate that the viable count of Bifidobacterium longum within the microcapsules remained consistently above 1 × 10⁶ CFU/g at 4 °C for 28 days, confirming their targeted release in the intestinal environment. In summary, this study has successfully addressed the key challenges associated with traditional spray-drying methods for probiotic microencapsulation, including poor stability, these findings provide valuable insights for the development and scalable production of probiotic products.