Encapsulation in alginate–skim milk microspheres improves viability of Lactobacillus bulgaricus in stimulated gastrointestinal conditions

Abstract

Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) was encapsulated in alginate–skim milk microspheres. Characteristics of encapsulated L. bulgaricus, such as pH stability, bile stability, storage stability and release property, were studied in this paper. The viability of free L. bulgaricus was not observed after 1 min in simulated gastric fluids (SGF) at pH 2.5 or 2.0. Compared with that of free L. bulgaricus, the viability of encapsulated L. bulgaricus only decreased 0.7 log CFU/g and 2 log CFU/g after 2.0 h incubation in SGF at pH 2.5 and pH 2.0, respectively. L. bulgaricus was also sensitive to bile solution. The viability of free L. bulgaricus was fully lost after 1 h incubation in 1 and 2% bile solution, while the viability of encapsulated L. bulgaricus was only lost 2 log CFU/g and 2.6 log CFU/g in 1 and 2% bile solution at the same time, respectively. Encapsulated L. bulgaricus could be completely released from microspheres in simulated intestinal fluid (pH 6.8) within 2 h. The viability of encapsulated L. bulgaricus retained around 8 log CFU/g when stored at 4°C for 30 days. The current encapsulation technique enables a large proportion of L. bulgaricus to remain good bioactive in a simulated gastrointestinal tract environment.

Keywords::

• encapsulation
• alginate
• skim milk
• probiotics
• stability

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. This study was financially supported by the Xinmiao Talent Programme of Zhejiang Province (2012R421003).

Notice of CorrectionThe Early Online version of this article published online ahead of print on 7 December 2012 contained an error on page 1. The author list “LIN-XIA PAN¹, XIU-JUAN FANG¹, ZHEN YU¹, YANG XIN¹, XIAO-YING LIU¹, LU-E SHI¹*, & ZHEN-XING TANG^2,3” should have read “LING-XIA PAN¹, XIU-JUAN FANG¹, ZHEN YU¹, YANG XIN¹, XIAO-YING LIU¹, LU-E SHI¹*, & ZHEN-XING TANG^2,3*”. This has been corrected for the current version.