Olof Mårtensson

The effect of yoghurt culture on the survival of probiotic bacteria in oat-based, non-dairy products

The survival of the probiotic strains Lactobacillus reuteri ATCC 55730, Lactobacillus acidophilus DSM 20079 and Bifidobacterium bifidum DSM 20456, all of human origin, were investigated in three different oat-based, non-dairy products (Adavena M40, MG20 and G40). The products were fermented by the three strains with and without the presence of a commercial yoghurt culture (V2). Samples were stored at 6 degreesC up to 30 days. In general, the oat-based products were shown to be a suitable support for these intestinal bacteria. L. reuteri ATCC 55730 had the highest viability in all of the products investigated. After 30 days the cell viability of L. reuteri ATCC 55730 was 10(8) CFU ml(-1) in all three oat-based products. Lower viability was seen when the strains were grown in the presence of the yoghurt culture compared to when they were grown as pure cultures. These products also exhibited a lower pH value in comparison to products fermented with the pure cultures. The milisation of the main fermentable carbohydrates in the products varied across the bacterial strains. A decrease in beta-glucan content was seen for the products fermented by the B. bifidum DSM 20456 strain. This work shows that these oat-bases with different mono- and disaccharide composition can be used to support the growth of human intestinal bacteria and also maintain high cell viability during cold storage.

Comparison of growth characteristics and exopolysaccharide formation of two lactic acid bacteria strains, Pediococcus damnosus 2.6 and Lactobacillus brevis G-77, in an oat-based, nondairy medium

The fermentation characteristics of two strains of lactic acid bacteria (LAB), Lactobacillus brevis G-77 and Pediococcus damnosus 2.6 were compared in an oat-based, nondairy milk medium (Adavena® G40). Viscosity and ropiness were the main growth parameters studied. Both strains are reported to produce an exopolysaccharide (EPS) with a -glucan structure; in addition, the L. brevis strain produces also an EPS with an -glucan structure. Both strains were able to ferment and produce EPS in the oat-based, nondairy medium to the extent that an obvious change was observed in terms of viscosity and ropiness during the fermentation period. These results show the potential of both LAB strains as possible starter cultures in new kinds of fermented, nondairy milk products. (Less)

Effects of fermented, ropy, non-dairy, oat-based products on serum lipids and the faecal excretion of cholesterol and short chain fatty acids in germfree and conventional rats

Three fermented, ropy, non-dairy, oat-based products were evaluated for their effect on serum lipids, faecal cholesterol and faecal short chain fatty acids in germfree and conventional rats. Three different exopolysaccharide (EPS) producing lactic acid bacteria strains were used to ferment the non-dairy oat-base (Adavena ® G40) (Ceba Foods AB, Lund, Sweden). Two commercial non-dairy products based on oats (Mill Milk™) (Ceba Foods AB, Lund, Sweden) and rice (Rice Dream ® ) (Imagine Foods, London, UK) were used as non-ropy and unfermented controls. All the standardized feeds were sterilized before being fed to the animals. Adult, germfree and conventional AGUS rats,

Characterization of the properties of Pediococcus parvulus for probiotic or protective culture use.

Pediococcus parvulus 2.6 (previously Pediococcus damnosus 2.6, here confirmed as P. parvulus by 16S DNA sequencing) displayed antibacterial activity toward several bacterial species, including isolates found as contaminants in oats, herein genetically identified as Bacillus cereus. No inhibition of Listeria monocytogenes was found under the conditions used. Antibacterial activity was retrieved after ammonium sulfate or acetone precipitation showed it to be peptide mediated. P. parvulus 2.6 has previously shown good technological properties in oat-based products. This, together with the currently found inhibition of food spoilage microorganisms like B. cereus, makes it suitable as a food protective culture. Survival trials of P. parvulus 2.6 at conditions mimicking the gastrointestinal tract were prompted by previously found cholesterol-lowering effects in humans after consumption of oat products cofermented by using P. parvulus 2.6 and Bifidobacterium spp. Viability was measured with in vitro, gutlike simulations at 37 degrees C. High survival was shown under two of three conditions (gastric juice, bile, and small intestine juice), defined as main obstacles of the gastrointestinal tract. The critical step was bile exposure. At a concentration of 20%, viability was low, but 0.3% bile (mean concentration in the intestine) did not have a major influence on growth. Viability of P. parvulus 2.6 was significantly decreased in gastric juice at pH 1.5 (with pepsin), but it was not significantly affected at pH 2.5, and was also improved at a lower pH in 20% oat milk. Viability was judged sufficient for colonization at gutlike conditions, qualifying the strain for further probiotic studies.