Application of probiotic bacteria in production of yoghurt preserved under high pressure†

†Presented at the 42nd EHPRG conference, Lausanne, Switzerland, September 1–4, 2004.

Abstract

The aim of this study was to determine the possibilities of using probiotic bacteria Lactobacillus acidophilus and Bifidobacterium ssp., as an additive to pressurized yoghurt. A pressure of 550 MPa/15 min/18 °C was applied. After pressurization, the probiotic bacteria in a lyophilized form and inactivated in milk were added. Yoghurts were stored for 4 weeks at a temperature of 4 °C. The pressure caused the complete reduction of Lactobacillus delbrueckii ssp. bulgaricus and reduction of the number of Streptococcus thermophilus by 1–2 orders of magnitude, and a small increase of the pH value. Therefore, by applying high pressures, the antibacterial activity of yoghurt is reduced. The addition of probiotic bacteria restores the lost properties. During the storage, the progressive reduction of live bacterial cells was observed. The number of L. acidophilus and Bifidobacterium ssp. was maintained on the level of 10⁶–10⁷ CFU/g till the end of the storage period.

†Presented at the 42nd EHPRG conference, Lausanne, Switzerland, September 1–4, 2004.

Keywords:

• Yoghurt
• High pressure
• Probiotic bacteria

Acknowledgements

The work was supported by National Grant (2004–2007) from State Committee for Scientific Research.

Notes

†Presented at the 42nd EHPRG conference, Lausanne, Switzerland, September 1–4, 2004.