Abstract
A study was conducted to evaluate the effect of inulin from Asparagus falcatus and Taraxacum javanicum on growth of Lactobacillus acidophilus (La-5) and Bifidobacterium animalis (Bb-12) in skim milk. Commercially available chicory inulin and chicory fructooligosaccharides (FOS) were used as positive controls. Skim milk (13% (w/v)) samples supplemented with different concentrations (0.5, 1, 2, 3 and 5%) of AF or TJ inulin, 5% Chicory inulin and 5% FOS, inoculated with mix culture of La-5 and Bb-12 (1:1), were incubated at 37 oC for 24 hours. The skim milk samples prepared the same way, but without adding inulin were used as negative controls. Optical density and pH of the milk samples were checked during 0, 6, 12 and 24 hours of incubation. Selective enumeration of La-5 and Bb-12, at 6 hours of incubation, was done using MRS-sorbitol agar and Beerens agar, respectively. The AF and TJ inulin showed enhanced bifidobacterial growth in skim milk, similar to chicory inulin. The growth promotion effect of AF and TJ inulin on bifidobacteria was maximal at 3% inulin concentration. None of the inulin types or FOS significantly influenced the La-5 growth in skim milk. The pH values of fermented milk samples were significantly (P<0.05) lower in inulin or FOS supplemented skim milks compared with the control. AF and TJ inulin showed clear bifidogenic properties in skim milk, indicating their potential use as alternative inulin sources for the Food Industry.