RESUMO
The bifidogenic effect of an infant formula supplemented with inulin and fructooligosaccharides (4.0 g/l) was examined clinically and in vitro, and compared that of mature breast milk. In a 28-day clinical study, fecal samples of 21 infants, divided into two groups: one receiving the infant formula and the other breast milk, were microbiologically and biochemically examined. In the in vitro investigation, microbiological and biochemical changes in the infant formula and breast milk induced by the action of bifidobacteria isolated from infant feces were examined. There were no significant differences in the fecal numbers of lactobacilli, total aerobes, anaerobes or yeasts and fungi. In contrast, the bifidobacteria numbers in the stools increased significantly during the study in the infants receiving the supplemented formula. The comparative in vitro test showed that the bifidogenic effect was similar for infant formula and breast milk in terms of the number of bifidobacteria. Consumption of infant formula with added inulin and fructooligosaccharides stimulated the bifidogenic effect, both clinically and in vitro. The in vitro test can quickly and objectively determine the bifidogenic effect of infant formula and indicate their quality. However, a clinical test is necessary to determine the acceptance and biological value of infant formula.
RESUMO
INTRODUCTION: The aim of this paper was to examine and to compare microbiological parameters of bifidogenesis as important indicators of bifidogenic effect in infant formulas, with and without inulin supplement as a prebiotic; we also evaluated the rationale for inulin supplementation in order to improve biofidogenesis. MATERIAL AND METHODS: Feces of healthy, breast-fed infants were used to examine and to isolate the accumulated culture of Bifidobacterium spp. Human milk and infant formulas (with or without inulin supplement) were used to examine the effect of substrate to bifidogenic effect. Pure chicory inulin was used as a natural prebiotic for the supplementation of infant formulas in concentration of 0.4 g and 0.8 g to 100/ml of substrate. In vitro effects of bifidogenesis were observed in all substrates by determining microbiological parameters at the beginning (index 0) and at the end of the experiments, after 48 hours (index 48). We observed and compared two microbiological parameters of bifidogenesis: the total number of bifidobacteria and dry biomass. Phase-contrast microscopy was used to identify Bifidobacterium spp. in accumulated mixed culture. The process of bifidogenesis was controlled by light transmission microscopy in light filed. Total number of Bifidobacterium spp. was determined by the method of serial dilution. Dry biomass was gravimetrically measured. Bifidogenic effect was calculated for each substrate. Dry biomass from the human milk substrate was used as a reference value. RESULTS: The obtained mean value of bifidogenic effect of standard milk formula was lower for 29% compared to mean value of bifidogenic index of human milk. The mean value of bifidogenic index of infant formula supplemented with 0.4 g and 0.8 g of inulin respectively was statistically significantly higher compared to the mean value of bifidogenic effect of human milk (>38% and >104%, respectively). CONCLUSION: The rationale for supplementation of infant formulas with inulin was confirmed.