Enrichment of conjugated linoleic acid in oats (Avena sativa L.) by microbial isomerization.
A method for microbial isomerization of oat linoleic acid to conjugated linoleic acid (CLA) was developed. The method includes hydrolysis of oat lipids in aqueous flour slurries by the endogenous oat lipase. Then, the flour slurry containing free linoleic acid is utilized as a substrate for the isomerization reaction carried out by resting cells of Propionibacterium freudenreichii ssp. shermanii. The isomerization reaction progressed most effectively when, after the lipid hydrolysis period, the pH of the slightly acidic oat slurry was elevated to 8.0-8.5 and maintained at this range. With slurries containing 5% (w/v) oat flour, the amounts of CLA formed per dry matter were up to 10.1 mg/g corresponding to 102 mg/g lipids or 0.44 mg/mL slurry. Increments in the flour content up to 15% increased the volumetric production of CLA to 0.85 mg/mL. The proportion of the cis-9,trans-11 isomer was 80% of the total CLA formed. CLA could be concentrated into the solid material of the oat slurry by acidification.
Vahvaselkä
Marjatta
M
Laboratory of Biochemistry and Microbiology, Helsinki University of Technology, P.O. Box 9400, FIN-02015 HUT, Finland. Marjatta.Vahvaselka@hut.fi
Lehtinen
Pekka
P
Sippola
Soili
S
Laakso
Simo
S
D018554:Avena / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007536:Isomerism; D019787:Linoleic Acid / Q000378:metabolism; D044243:Linoleic Acids, Conjugated / Q000737:chemistry* / Q000378:metabolism*; D008049:Lipase / Q000378:metabolism; D050356:Lipid Metabolism; D011424:Propionibacterium / Q000378:metabolism*
D044243:Linoleic Acids, Conjugated; D019787:Linoleic Acid; D008049:Lipase