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R.G. CRITTENDEN, L.F. MORRIS, M.L. HARVEY, L.T. TRAN, H.L. MITCHELL AND M.J. PLAYNE. 2001.

Aims: To employ an in vitro screening regime to select a probiotic Bifidobacterium strain to complement resistant starch (Hi-maize™) in a synbiotic yoghurt.

Methods and Results: Of 40 Bifidobacterium isolates examined, only B. lactis Lafti™ B94 possessed all of the required characteristics. This isolate hydrolysed Hi-maize™, survived well in conditions simulating passage through the gastrointestinal tract and possessed technological properties suitable for yoghurt manufacture. It grew well at temperatures up to 45°C, and grew to a high cell yield in an industrial growth medium. In addition to resistant starch, the organism was able to utilize a range of prebiotics including inulin, and fructo-, galacto-, soybean- and xylo-oligosaccharides. Pulse field gel electrophoresis of restriction enzyme cut chromosomal DNA revealed that B. lactis Lafti™ B94 was very closely related to the B. lactis Type Strain (DSM 10140), and to the commercial strains B. lactis Bb-12 and B. lactis DS 920. However, B. lactis Lafti™ B94 was the only one of these isolates that could hydrolyse Hi-maize™. This phenotypic difference did not appear to be due to the presence of plasmid encoded amylase. Bifidobacterium lactis Lafti™ B94 survived without substantial loss of viability in synbiotic yoghurt containing Hi-maize™ during storage at 4°C for six weeks.

Conclusions:Bifidobacterium lactis Lafti™ B94 is a promising new yoghurt culture that warrants further investigation to assess its probiotic potential.

Significance and Impact of the Study:In vitro screening procedures can be used to integrate complementary probiotic and prebiotic ingredients for new synbiotic functional food products.