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

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 (W1O/W-2) Pickering emulsion stabilized by inclusion complexes having d(32) of 3.6 mu m formed from beta-cyclodextrin (beta-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 W-1/O/W-2 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 H-1 nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM) and the solid inclusion complex formation between beta-CD and double emulsion contents was confirmed. The existence of L dellbrueckii in beta-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 beta-CD compared to Tween-80. It is concluded that the double emulsion prepared using beta-CD protected L dellbrueckii and the experimental findings of the present study are a fundamental guide for practical applications in food industry. (C) 2016 Elsevier Ltd. All rights reserved.