Application of magneto‐responsive Oenococcus oeni for the malolactic fermentation in wine

Abstract

A new method for magnetic separation of the magnetized lactic acid bacteria (LAB) Oenococcus oeni at a desired stage of the malolactic fermentation (MLF) in wine was developed. The method includes the bonding of functionalized magnetic nanoparticles to the bacterial surface in the suspension, the application of the “magneto‐responsive” bacteria (MRB) in the fermentation process and their magnetic separation from the wine using high‐gradient magnetic separation (HGMS). The controlled attachment of the superparamagnetic amino‐functionalized silica‐coated maghemite nanoparticles (aMNPs) to the O. oeni was developed. The MRB were applied in the MLF and separated from the fermentation process at a certain stage using the HGMS. From the results it was found that the magnetization of the bacteria using aMNPs attached to the cell surface had no influence on the O. oeni metabolism. The O. oeni with the attached magnetic nanoparticles were efficiently removed from the fermentation media using HGMS, which resulted in a complete stop of the fermentation process.