Lactic acid bacteria fermentations in oat-based suspensions

Olof Mårtensson

Research output: ThesisDoctoral Thesis (compilation)

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Abstract

This thesis deals with the fermentation characteristics of lactic acid bacteria (LAB) in oat-based suspensions, with formulation work of fermented products based on oat and with nutritional studies of these products. Changes in structure in terms of viscosity and ropiness were studied when exopolysaccharide (EPS)-producing LAB strains, namely, Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772, Lactobacillus brevis G-77 and Pediococcus damnosus 2.6 were grown in these oat-based suspensions. Differences in structure were seen after growth of EPS-producing bacteria, resulting in higher viscosity and ropiness in these products. The formulation work of fermented products was carried out by using commercial yoghurt cultures with and without the presence of an EPS-producing strain. The products developed were found to have sensory acceptance and good bacterial survival during storage. The bacterial survival of three probiotic strains, Lactobacillus reuteri ATCC 55730, Lactobacillus acidophilus DSM 20079 and Bifidobacterium bifidum DSM 20456, was also studied in different oat-based suspensions with and without the influence of a yoghurt culture during 30 days of storage. The highest survival was seen for the Lactobacillus reuteri strain. The co-fermentation in the presence of a yoghurt culture gave a lower pH in the final products and decreased the survival rates for all strains. The nutritional effects of fermented, oat-based products were investigated by using germfree and conventional rats and by performing a clinical study on 56 healthy subjects. Physiological parameters such as changes in serum cholesterol, faecal excretion of cholesterol, and amount of faecal short chain fatty acids (SCFA) were studied. In addition, changes in the faecal flora were investigated in the human subjects. No changes in the serum cholesterol levels or faecal excretion of cholesterol were seen in the rat models when the animals were fed on different, fermented oat-based products. A diffeent feacal SCFA pattern was seen in the conventional rats fed on the oat-based diets than in the group fed on rice. A lipid lowering effect was seen in the human subjects eating a fermented, ropy, oat-based product for five weeks, which gave a dietary intake of 3.5 g native beta-glucans from oat per day. An increase in total bacterial count and Bifidobacterium subsp. was also seen in faecal samples from these subjects.

In conclusion, there is a potential for the development of fermented, non-dairy, oat-based products with a "ropy" structure containing soluble fibres of both native and microbial origin and with the lipid lowering effect that is generally associated with an intake of oat.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Biotechnology
Supervisors/Advisors
  • [unknown], [unknown], Supervisor, External person
Award date2002 Jun 13
Publisher
Print ISBNs91-89627-09-1
Publication statusPublished - 2002

Bibliographical note

Defence details

Date: 2002-06-13
Time: 10:15
Place: Lecture hall C of Center for Chemistry and Chemical Engineering, Getingevägen 60, Lund

External reviewer(s)

Name: Salovaara, Hannu
Title: Professor
Affiliation: Department of Food Technology, University of Helsinki, Finland

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Article: Lactic acid bacteria in an oat-based non-dairy milk substitute: Fermentation characteristics and exopolysaccharide formation.Olof Mårtensson, Rickard Öste and Olle Holst (2000).Food Science and Technology/LWT 33, 525-530.

Article: Texture promoting capacity and EPS-formation by lactic acid bacteria in three different oat-based media.Olof Mårtensson, Rickard Öste and Olle Holst (2002).European Food Research and Technology 214, 232-236.

Article: 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, non-dairy medium.Olof Mårtensson, Maite Dueñas-Chasco, Ana Irastorza, Rickard Öste and Olle Holst(Submitted)

Article: Formulation of an oat-based fermented product and its comparison with yoghurt.Olof Mårtensson, Carina Andersson, Kenneth Andersson, Rickard Öste and Olle Holst (2001).Journal of the Science of Food Agriculture 81, 1314-1321.

Article: A fermented, ropy, non-dairy oat product based on the exopolysaccharide-producing strain Pediococcus damnosus.Olof Mårtensson, Johan Staaf, Maite Dueñas-Chasco, Ana Irastorza, Rickard Öste and Olle Holst (2002).Advances in Food Sciences 24, 4-11.

Article: The effect of yoghurt culture on the survival of probiotic bacteria in oat-based, non-dairy products.Olof Mårtensson, Rickard Öste and Olle Holst (2002).Food Research International (in press).

Article: The effect of fermented, ropy, non-dairy, oat-based products on serum lipids and the faecal excretion of cholesterol and short chain fatty acids in germfree amd conventional rats.Olof Mårtensson, Maite Dueñas-Chasco, Ana Irastorza, Olle Holst, Mats Rudling, Elisabeth Norin, Tore Midtvedt and Rickard Öste.(submitted)

Article: Changes in plasma lipids and faecal Bifidobacterium spp. in humans after consumption of fermented, non-dairy, oat-based products for 5 weeks.Gunilla Önning, Olof Mårtensson, Adele Mbou Lambo, Maria Biörklund, Maite Dueñas-Chasco, Ana Irastorza, Olle Holst, Elisabeth Norin, Gjalt Welling, Björn Åkesson and Rickard Öste.(Manuscript)

Subject classification (UKÄ)

  • Industrial Biotechnology

Keywords

  • beta-glucans
  • probiotics
  • prebiotics
  • bacterial survival
  • Food and drink technology
  • Livsmedelsteknik
  • oats
  • ropiness
  • lactic acid bacteria
  • ropy

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