The term Lake is derived from the Arabic word lac; from the lac beetle. Lakes are formed by the precipitation of a pigment with a salt, resulting in an oil-dispersible compound that can be easily mixed with a dry medium. For example, aluminium-based lakes are pigments formed by the precipitation of a substance such as a synthetic, water-soluble food dye with aluminium hydroxide in the form of an aluminium salt.
The addition of colours to foods has been observed since Egyptian times and are used primarily to make food seem more appealing to consumers. Lake food colours differ from food dyes in that they are insoluble in water. Combining the pigment with salt, makes Lakes more stable than dyes alone, resulting in greater colour fastness. They also benefit from flavourlessness, meaning they do not alter the taste of their substrate, making them perfect for consumable products.
Lakes are ideal for colouring oil-based foods, or products lacking enough moisture to dissolve dyes. They are therefore widely used in the pharmaceutical industry for coated tablets and cosmetics, as well as in the food industry in hard sweets, candy and chewing gum. They are popular for their versatility, stability, and oil-solubility and additionally come in a wide range of colours.
Their stability makes them suitable for products with long self-lives such as cosmetics, such as lipstick, where pigments are expected to maintain their vibrancy for several years. Aluminium lakes are also a popular additive in personal care products such as soaps, shampoos, and creams. Their stability allows them to be used without over-coating.
Most household disinfectants used for airborne pathogens contain hazardous substances, such as ozone or hydrogen peroxide, which are harmful to human health as they can cause respiratory problems. They can also contain metallic nanoparticles, which have been shown in some cases to be carcinogenic. This has resulted in research into new disinfection methods for airborne pathogens and has only accelerated during the pandemic.
Researchers at Purdue University have developed a novel way to use food colour dyes to kill pathogens in the air. They discovered that the food dyes can be used to generate singlet oxygen (an unstable form of molecular oxygen), which has long been known to denature pathogens. If the use of food dye-based methods is approved, it could be used as a safe way to disinfect public spaces and hospitals. Most health care workers are infected while removing PPE. The researchers are currently developing an aerosol system that can be installed in a disinfection chamber, to make the removal of PPE safer.