Probiotic viability during gastrointestinal transit is critical for their functional efficacy but is compromised by acidic pH and enzymatic degradation. This study developed a buckwheat protein–shellac (BW–SH) co-folded complex to stabilize W/O/W double emulsions for protecting Lactiplantibacillus plantarum during gastrointestinal transit. Co-folding with shellac not only enhanced BW’s functionality as an emulsion stabilizer but also facilitated the formation of a pH-driven BW–SH complex through hydrogen bonding and hydrophobic interactions, as confirmed by UV, fluorescence, and FTIR spectroscopy. The optimized BW–SH complex (BWS-1, pH 9) exhibited a fibrillar morphology (TEM) and a highly negative ζ-potential (−61.4 ± 1.17 mV). pH-shifting with shellac effectively improved the emulsifying activity and stability of BW. Double emulsions stabilized by the BW–SH complex achieved a higher encapsulation efficiency (95.56%) and viable cell count (7.5 log CFU/mL, vs. 4.0 log CFU/mL for free cells) after in vitro gastrointestinal digestion, demonstrating that the oil layer and BW–SH interfacial adsorption synergistically protected the probiotics. Microscopic imaging further revealed pH-dependent structural retention, with gradual disintegration correlating with sustained probiotic viability. Overall, this study provides a scalable strategy for probiotic delivery using grain protein–shellac hybrids, addressing key challenges in functional food and nutraceutical applications. • BWS complexes stabilized W/O/W emulsions with improved structural integrity. • Shellac co-folding markedly increased L. plantarum survival during GI digestion. • pH 9–driven BWS complexes exhibited fibrillar morphology and high ζ-potential. • BWS emulsions achieved high encapsulation and sustained probiotic release.
Guo et al. (Sun,) studied this question.