Encapsulating role of β-cyclodextrin in formation of pickering water-in-oil-in-water (W1/O/W2) double emulsions containing Lactobacillus dellbrueckii

Abstract

Lactobacillus dellbrueckii cultured in MRS and harvested in the late log phase was entrapped in the inner aqueous phase of a water-in-oil-in-water (W1/O/W2) Pickering emulsion stabilized by inclusion complexes having d32 of 3.6 μm formed from β-cyclodextrin (β-CD) and the results were compared to the corresponding double emulsions with Tween-80 as the secondary emulsifier. The stability of emulsions prepared at various primary emulsion contents and emulsifier concentrations was investigated. Emulsion morphology was observed by polarization microscopy and size distributions of dispersed droplets were examined to establish emulsion stability. The solid-like property of the test W1/O/W2 emulsions was found to dominate based on the oscillatory experiments results (G′>G″). The precipitated fraction obtained upon centrifugation of the emulsion phase was structurally characterized using 1H nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM) and the solid inclusion complex formation between β-CD and double emulsion contents was confirmed. The existence of L. dellbrueckii in β-CD containing emulsions was evidenced by Fourier transform infrared (FTIR) spectroscopy in ATR geometry and fluorescence microscopy. Moreover, the survival of the entrapped cells (initial number = 8.17 log CFU/ml) increased significantly with use of β-CD compared to Tween-80. It is concluded that the double emulsion prepared using β-CD protected L. dellbrueckii and the experimental findings of the present study are a fundamental guide for practical applications in food industry.