Microencapsulation of Bifidobacterium bifidum F-35 via modulation of emulsifying technique and its mechanical effects on the rheological stability of set-yogurt

Abstract

Microencapsulation of B. bifidum F-35 was carried out through emulsification technique in order to increase the microbial load while maintaining the rheological functions of set-yogurt. To produce single-layer (SL) microcapsules of whey protein, the pH was adjusted to 6.4 within Transglutaminase-induced gelation. Sodium alginate was processed as the external layer using calcium-induced gelation (pH 5.5) to produce the double-layer (DL) microcapsule. Scanning electron microscopy revealed that SL and DL microcapsules had sizes of 10 and 280 μm, respectively. The highest microbial load was clearly visible in the DL sample. According to texture profile analysis, the DL sample had the highest levels of gumminess, chewiness, and adhesiveness. The free sample outperformed the encapsulated samples in terms of springiness and cohesiveness. Although the SL sample had the highest viscosity, it produced a deformed gel when firmness was measured. In terms of firmness, the DL sample performed quite well. The viability of encapsulated B. bifidum F-35 in DL was higher than SL microcapsules during storage. Microencapsulation of B. bifidum F-35 with whey protein and sodium alginate is a promising technique that could improve the rheological properties of set-yogurt as a popular vehicle for bioactive ingredients.

Keywords: Bifidobacterium bifidum; Emulsification technique; Microencapsulation; Set-yogurt; Sodium alginate; Whey protein.

Fig. 1

Scanning electron photomicrograph of whey protein microcapsule MC_WP (SL)

Fig. 2

Scanning electron photomicrograph of whey protein-sodium alginate microcapsule MC_WP−AL (DL)

Fig. 3

Total viable counts of lactic acid bacteria (log CFU g⁻¹) in set-yogurt during 14 days at 4 ± 1 °C

Fig. 4

Total viable counts of B. bifidum F-35 (log CFU g⁻¹) in set-yogurt during 14 days at 4 ± 1 °C