Water-in-water Pickering emulsion: A fascinating microculture apparatus for embedding and cultivation of Lactobacillus helveticus

Currently, the cultivation of lactic acid bacteria is mainly carried out by improving the fermentation process and culture conditions, which was difficult to ensure the survival quantity and culture efficiency. The primary purpose of this work was to construct water-in-water (W/W) Pickering emulsion as a microculture for probiotics. The W/W Pickering emulsion consisting of maltodextrin (MD) and hydroxypropylmethylcellulose (HPMC) was constructed by using microcrystal celluloses (MCC) as the Pickering stabilizers. The effects of MCC concentration, NaCl concentration, MRS broth concentration, and pH value on the formation and stability of W/W Pickering emulsion have been investigated. The stability of W/W Pickering emulsions was driven by the electrostatic repulsion provided by the MCC. The stability of the emulsion was reduced by increasing NaCl and MRS broth concentrations, primarily because their charge shielding effect weakened the electrostatic repulsion between the MCC particles. The W/W Pickering emulsion had higher stability in a weakly acidic environment. The results from another trial revealed that Lactobacillus helveticus CICC 22,536 had little influence on the stability of the W/W Pickering emulsion when it was encapsulated in the emulsion. Moreover, Lactobacillus helveticus was able to be cultured in the emulsion, and the numbers of Lactobacillus helveticus after being cultured for 16 h were increased to 1.1 × 109 CFU/mL. These findings indicated that the W/W Pickering emulsion provided a new approach and an attractive platform for the cultivation of probiotic bacteria.