Synergistic effects of pH and nano-calcium carbonate on sodium alginate gels and their application for encapsulation, protection, delivery and yoghurt of probiotics

Utilisation of advanced encapsulation technology is imperative for the enhancement of probiotic survival throughout processing, storage, and digestion. In this study, the gel was physically modified based on the pH sensitivity of nano calcium carbonate (NC) and sodium alginate (SA). The resistance of Bifidobacterium lactis BL-99 under modified gel encapsulation was evaluated. Findings indicated that NC-SA exhibited a denser cross-linked network structure, presented enhanced strength, elasticity, viscosity, and water-holding capacity, and demonstrated a 95.28% encapsulation efficiency of BL-99. In comparison to the SA gel, the survival rate of BL-99 encapsulated by the NC-SA modified gel was observed to be enhanced by 14.1% under pasteurisation. Moreover, the number of viable cells after 6 h of simulated gastrointestinal digestion remained above 8 Log CFU/g. Furthermore, the NC-SA gel was applied to the yoghurt, and it was found that BL-99 was still able to maintain above 7 Log CFU/mL with a survival rate of 86.99% (21 days, 4 °C). This study confirmed the potential of the NC synergistic system pH-modified SA gel to protect probiotic activity. It is, therefore, expected that this technology will be applied in acidic liquid food matrices. • NC-SA gel has dense network structure and excellent gel properties. • The encapsulation rate of BL-99 by NC-SA-modified gel reached 95.28%. • NC-SA gel can improve the survival rate of BL-99 in pasteurisation. • The biomass of encapsulated BL-99 was 78.9% after 28 days of storage. • The encapsulated BL-99 in yoghurt maintained >7 log CFU/g after 21 days.