Microbial enrichment of blackcurrant press residue with conjugated linoleic and linolenic acids

Aims The aim of the study was to investigate the isomerization of linoleic (LA) and linolenic acids (LNAs) into their conjugated isomers byPropionibacterium freudenreichiiDSM 20270 and utilize this feature for microbial enrichment of blackcurrant press residue (BCPR) with health-beneficial conjugated fatty acids. Methods and Results First, the ability ofP. freudenreichiito isomerize 0 center dot 4 mg ml(-1)of LA and LNA was studied in lactate growth medium. Free LA and alpha-LNA were efficiently converted into conjugated linoleic (CLA) and alpha-linolenic acid (alpha-CLNA), being the predominant isomersc9,t11-CLA andc9,t11,c15-CLNA, respectively. The bioconversion of alpha-LNA byP. freudenreichiiwas more efficient in terms of formation rate, yield and isomer-specificity. Thereafter, free LA and LNAs obtained from hydrolysed BCPR neutral lipids, by lipolytically active oat flour, were subjected to microbial isomerization in BCPR slurries. In 10% (w/v) slurries, a simultaneous enrichment inc9,t11-CLA andc9,t11,c15-CLNA of up to 0 center dot 51 and 0 center dot 29 mg ml(-1)was observed from starting levels of 0 center dot 96 mg LA ml(-1)and 0 center dot 37 mg alpha-LNA ml(-1)respectively. Conclusions This study shows that growing cultures ofP. freudenreichiiDSM 20270 are able to simultaneously enrich BCPR with health-beneficial conjugated isomers of LA and alpha-LNA. Significance and Impact of the Study This study demonstrates that microbial isomerization technique can be utilized to enrich lipid-containing plant materials with bioactive compounds and thereby enable valorization of low value plant-based side streams from food industry into value-added food ingredients.

Automated summary

This study demonstrates that Propionibacterium freudenreichii DSM 20270 can simultaneously enrich blackcurrant press residue with health-beneficial conjugated isomers of LA and alpha-LNA. The microbial isomerization technique can be utilized to enrich lipid-containing plant materials with bioactive compounds, enabling valorization of low value plant-based side streams from the food industry into value-added food ingredients.