Cold treatment

A nanofiltration process for purifying an essential oil for a fragrance, flavour or cosmetic ingredient by removing synthetic pesticide or fungicide impurities, comprising the following steps:

• (i) providing a selectively permeable thin film composite (TFC) nanofiltration membrane, wherein the membrane consists of a top layer and a more porous chemically different layer, wherein the top layer comprises a material selected from the group consisting of polyoctylmethylsiloxane, poly[1-(trimethylsilyl)-1-propyne], poly(2,6-dimethyl-1,4-phenylene oxide), polyacrylonitrile, polymer of intrinsic microporosity (PIM-1), polystyrene-b-poly(ethylene oxide) diblockcopolymer, poly(sodiumstyrenesulphonate) (PSS) or polyvinylsulphate (PVS) and mixtures thereof
• and wherein the TFC nanofiltration membrane has a molecular weight cut-off of between 150 g/mol and 1200 g/mol;
• (ii) providing a flowable input of essential oil, with a solvent component;
• (iii) separating the flowable input by transferring it across the surface of the membrane to form a retentate and a permeate, such that the concentration of one or more components of the permeate is reduced compared to the flowable input;
• wherein the flow rate through the membrane is at least 8 kg [permeate]/h*m2 [membrane];
• and wherein the permeate is decoloured in comparison to the flowable input, such that the lightness value L* of the permeate is increased in comparison to the flowable input to ΔL* greater than or equal to 1 and the chromaticity C* of the permeate is decreased in comparison to the flowable input to ΔC* less than or equal to −2, according to the CIELAB colour measurement system, as specified by the International Commission on Illumination;
• (iv) collecting the permeate and removing the solvent.