Effect of oligofructose on the microflora of an ABT-type fermented milk during refrigerated storage

The aim of this research was to investigate the influence of oligofructose on the microbial flora of a probiotic fermented dairy product during refrigerated storage. Oligofructose-supplemented and control fermented acidophilus-bifidus-thermophilus (ABT) milks were produced using a fast fermentation starter culture as the source of Lactobacillus acidophilus (A), bifidobacteria (B), and Streptococcus thermophilus (T), and were then stored at 4°C for 42 d. Microbiological analyses and acidity measurements were performed at weekly intervals. Our results showed that the presence of oligofructose at 1.0 to 5.0% (w/v) did not significantly influence (p > 0.05) the survival of either S. thermophilus or L. acidophilus during storage. The viable counts of bifidobacteria fell more sharply than did those of lactobacilli and streptococci; however, the addition of oligofructose had a significantly beneficial effect (p<0.05) on their viability. No spoilage organisms were detected at any sampling time, indicating the high degree of sanitation during processing and packaging of the fermented milk products. In conclusion, the commercial oligofructose product tested was found to have prebiotic properties for bifidobacteria and, thus, it is suitable for improving the viability of bifidobacteria in refrigerated fermented dairy foods.