title: Production of folate in oat bran fermentation by yeasts isolated from barley and diverse foods.
abstract: OBJECTIVE
  The focus of the research was to identify yeasts from barley kernels in order to study their folate production capability while maintaining high viscosity caused by soluble fibres in oat bran fermentation.
  
  
  RESULTS
  The 65 isolated yeasts were characterized by API carbohydrate utilization tests, and assays for extracellular enzyme activities were the following: amylase, beta-glucanase, cellulase or CMCase, lipase, protease and xylanase. Yeasts were identified by partial DNA sequencing of the 25S D1/D2 and ITS1-5.8S-ITS2 regions. They belonged to the genera Aureobasidium, Cryptococcus, Pseudozyma and Rhodotorula. Folate production was determined from supernatant and cells grown in a rich laboratory medium or directly from oat bran solution inoculated with the appropriate yeast. Food yeasts, Saccharomyces cerevisiae, Candida milleri, Kluyveromyces marxianus and Galactomyces geotrichum, were used for comparison. Most of the yeasts isolated from barley destroyed the solid, viscous structure of the oat bran solution, indicating that they degraded the viscosity-generating soluble fibres, considered to be nutritionally advantageous. The best folate producers were S. cerevisiae, followed by Pseudozyma sp., Rhodotorula glutinis and K. marxianus. The yeasts maintaining high viscosity were used together with lactic acid bacteria (LAB) Streptococcus thermophilus or Lactobacillus rhamnosus to ferment oat bran solution. None of the yeasts isolated from barley, contrary to S. cerevisiae and C. milleri, produced together with LAB significant amounts of folate.
  
  
  CONCLUSIONS
  Fermentative yeasts together with LAB are potential for use in developing novel high folate content healthy foods and snacks from oat bran.
  
  
  CONCLUSIONS
  High soluble fibre content and high natural folate content but low energy content food and snack products with pleasant fermentation aroma provide possibilities for new developments in the food industry.
authors.affiliation: Department of Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Korhola
authors.forename: R
authors.initials: R
authors.lastname: Hakonen
authors.forename: K
authors.initials: K
authors.lastname: Juuti
authors.forename: M
authors.initials: M
authors.lastname: Edelmann
authors.forename: S
authors.initials: S
authors.lastname: Kariluoto
authors.forename: L
authors.initials: L
authors.lastname: Nyström
authors.forename: T
authors.initials: T
authors.lastname: Sontag-Strohm
authors.forename: V
authors.initials: V
authors.lastname: Piironen
mesh_terms: D018554:Avena; D004043:Dietary Fiber; D005285:Fermentation; D005492:Folic Acid / Q000096:biosynthesis*; D005516:Food Microbiology; D001467:Hordeum / Q000382:microbiology*; D052201:Lacticaseibacillus rhamnosus / Q000378:metabolism; D048249:Streptococcus thermophilus / Q000378:metabolism; D015003:Yeasts / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D004043:Dietary Fiber; D005492:Folic Acid
keywords: barley; folates; lactic acid bacteria; oat bran; yeast