Methods and compositions are provided for producing purified oil from an organism, whether these organisms are wild type, selectively bred or genetically modified, and are suitable for the large scale production of an oil product. The organism may be an animal, a plant or a microorganism such as yeast, bacteria or algae. The organism is processed to create a biomass which can be extracted to remove the lipids contained within the biomass. The extraction produces a crude extract rich in lipids and containing residual contaminants. These contaminants are removed by contacting the crude extract with a composition that comprises a nanomaterial. Subsequently an oil product is recovered which is substantially free from residual contaminants, such as pigments.