The potential use of hydrolysed konjac glucomannan as a prebiotic

Konjac glucomannan hydrolysate was derived enzymatically from konjac flour under optimal conditions. A number of culture strains of lactobacilli and bifidobacteria were grown on De Man, Rogosa and Sharpe (MRS) media supplemented with the hydrolysate. This hydrolysate stimulated the growth of all strains examined. Colony sizes of those strains grown on konjac hydrolysate were significantly (P = 0.001) bigger than those grown on pectin or xylan hydrolysates. Bacterial growth profiles were also conducted on nutrient agar (MRS or modified MRS agar containing konjac hydrolysate) using single strains of lactobacilli or bifidobacteria (Lactobacillus acidophilus, Lactobacillus casei or Bifidobacterium adolescentis), single pathogen cultures (Escherichia coli or Listeria monocytogenes) or mixed bacterial cultures (from chicken breast extract). Although the growth of lactobacilli inhibited the growth of pathogens (single or mixed culture) the pathogens could not grow on the konjac hydrolysate as a sole carbon source. Microbial growth profiles using konjac hydrolysate or inulin in UHT milk were also investigated. The results showed that the numbers of colony forming units (cfu) obtained from milk containing the konjac hydrolysate were significantly (P = 0.01) higher than those containing inulin. It is suggested that the unique properties of konjac hydrolysate make it universally valuable as a prebiotic which can be applied to a wide range of foods, feeds and healthcare/pharmaceutical products. (c) 2007 Society of Chemical Industry.