Growth and survival of Bifidobacterium in soy beverage

Abstract

The objective of the research study was to assess the potential use of soy beverage as a medium for the growth and survival of Bifidobacterium and, also, to determine the effect of added sugars on the survival thereof. The study was divided into two stages: at the first stage, the growth and survival of Bifidobacterium strains were studied in fermented and unfermented soy beverage. At the second stage, the effect of added sugars (glucose and oligofructose) was investigated on the growth and survival of a selected Bifidobacterium strain in the soy beverage. The soy beverage was inoculated with a 5 % (v/v) inoculum of the 24-hour culture of the Bifidobacterium population, its count being between 8.7 and 9.2 log cfu/ml depending on the strain applied. In the unfermented samples, after 7 days of refrigerated storage thereof, the number of cells significantly decreased to a value of 5.8 - 4,1 cfu/ml. However, after fermentation (37 °C/24 h), the number of Bifidobacterium cells increased by approximately 2 logarithmic orders, except for the sample with the A6 strain added. The selected strain of B. longum BIM B-647 was characterized by a high biomass production (already after 15 h fermentation) > 8.7 log cfu/ml. The addition of oligofructose significantly impacted the increase in the number of B. longum BIM B-647 cells in the soy beverage during fermentation and it also caused the stationary phase during cold storage of the samples to extend. The soy drink is a good carrier for the Bifidobacterium and it can be used to produce new probiotic foods.