Optimization of composite cryoprotectant for freeze-drying Bifidobacterium bifidum BB01 by response surface methodology

Abstract

Freeze drying has been well applied in the preparation of high-efficiency probiotic powders. However, the process is generally accompanied by probiotic viability deficiency, which is the bottleneck for further application. To improve the viability of Bifidobacterium bifidum BB01 during freeze-drying, we optimized the cryoprotectant of B. bifidum BB01 by response surface methodology (RSM) with a Central Composite Design (CCD). In this study, two values of B. bifidum BB01 with different protectant factors were investigated, including freeze-drying survival rate and the viable counts of per unit weight of freeze-dried powder. The optimized cryoprotectants were obtained as follows: glycine of 5.5%, sodium bicarbonate of 0.8%, xylo-oligosaccharides of 7%, arginine of 4.5% and skim milk of 25%. The survival rate and the viable counts of per unit weight of powder were 90.37 ± 1.9% and (2.78 ± 0.13) × 10¹¹cfu·g⁻¹, respectively, both close to the predicted value (88.58% and 2.71 × 10¹¹ cfu·g⁻¹). Our research demonstrated that RSM was successful in optimizing composite cryoprotectant for freeze-dried powder of B. bifidum which can as well protect the probiotic cells.

Keywords:

• Composite cryoprotectant
• Bifidobacterium bifidum
• freeze drying
• response surface methodology

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was partly supported by key industry innovation chain project of Science and Technology Department of Shaanxi Province2018ZDCXL-NY-01–01 the science and technology project of Xi’an city10.13039/5011000083872017050NC/NY007(1)The work was funded by the key industry innovation chain project of Science and Technology Department of Shaanxi Province [No.2018ZDCXL-NY-01–01], the science and technology project of Xi’an city [2017050NC/NY007(1)].