Multilayer Double Emulsion Encapsulation of Limosilactobacillus reuteri Using Pectin-Protein Systems

The development of bakeable foods supplemented with probiotics requires novel strategies to preserve the functionality of probiotic cells during thermal and gastrointestinal stress conditions. The objective of the present study was to evaluate the protective effect of multilayer double emulsions (W1/O/W2) stabilized with pectin-protein complexes on the viability of Limosilactobacillus reuteri (Lr) under thermal treatment (95 °C, 30 min), storage (4 °C, 28 d), and simulated gastrointestinal conditions. Emulsions were prepared with whey protein isolate (WPI) or sodium caseinate (Cas) as outer aqueous phase emulsifiers, followed by pectin coating and ionic gelation with calcium. All emulsions were stable and exhibited high encapsulation efficiency (>92%) with initial viable counts of 9 log CFU/mL. Double emulsions coated with ionically gelled pectin showed the highest protection against heat stress and gastrointestinal conditions due to the formation of a denser layer with lower permeability, regardless of the type of protein used as an emulsifier. At the end of storage, Lr viability exceeded 7 log CFU/mL in cross-linked pectin-coated microcapsules. These microcapsules maintained >6 log CFU/mL after thermal treatment, while viability remained >6.5 log CFU/mL during digestion and >5.0 log CFU/mL after consecutive heat treatment and simulated digestion. According to these results, the combination of double emulsion, multilayer formation and ionic crosslinking emerges as a promising microencapsulation technique. This approach offers enhanced protection for probiotics against extreme thermal and digestive conditions compared to previous studies that only use double emulsions. These findings support the potential application of this encapsulation method for the formulation of functional bakeable products.