Like kids having trouble coloring inside the lines, grown-up developers can face difficulties keeping their colors within the desired matrix. In these cases, a technologist’s best choice may be to jump into the “lakes.”
Navigating the regulations
According to Title 21 of the Code of Federal Regulations (CFR), Part 70, Subpart A, Section 70.3 (l), “The term lake means a straight color extended on a substratum by adsorption, co-precipitation, or chemical combination that does not include any combination of ingredients made by simple mixing process.”
Further, 21 CFR, Part 82, Subpart B, Section 82.51 (a1) describes the production of lakes as “...made by extending on a substratum of alumina (suspension in water of precipitated aluminum hydroxide), a salt prepared from one of the certified water-soluble straight colors hereinbefore listed in this subpart by combining such color with the basic radical aluminum or calcium.”
In plain English, “lakes” are water-soluble FD&C dyes that are combined with an insoluble material, typically alumina hydrate. “The exact controlling of the specific process parameters is crucial to guarantee batch to batch consistency in the key lake characteristics, such as shade, flowability and dispersability,” says Thomas Lampe, director of marketing, Sensient Food Colors N.A., St. Louis.
Lakes are identified in ingredient listings by three-part names: (1) the listed name of the color from which the lake is prepared; (2) the name of the basic radical combined in such color; (3) the word “lake.” For example, the name of a lake prepared by extending the aluminum salt prepared from FD&C Blue No. 1 upon the substratum would be FD&C Blue No. 1—Aluminum Lake (21 CFR Part 82, Subpart B, Section 82.51 (2b)).
Technically speaking, any dye can be turned into a lake. Legally speaking, only six synthetic colors have lake counterparts approved by FDA: FD&C Yellow No. 5; FD&C Yellow No. 6; FD&C Red No. 40; FD&C Blue No. 1; FD&C Blue No. 2; and FD&C Green No. 3. One natural color, carmine, also has an approved lake version.
“FD&C Green 3 is not offered in a lake form because one can make a blend of FD&C Yellow 5 Lake and FD&C Blue 1 Lake and yield the same shade at a much lower price than producing FD&C Green 3 Lake,” says Penny Martin, manager, technical services, Sensient Food Colors N.A.
Superior performance
Avoiding color migration is the major reason to use lakes. A water-soluble colorant will move whenever and wherever water moves. Lakes impart their pigments to foods, not by solubilization, but by evenly dispersing colored particles, some as small as 0.5 microns, throughout the product.
By adding lakes to a dry mix, technologists can achieve a completely homogenous blend. Dispersion methods are a key consideration for developers, and may vary with the form of the lake used.
“Lakes tend to agglomerate as a dry powder, and require shear to optimally disperse throughout a system,” Martin says. “If a liquid can be used in the system, most companies prefer to use dispersion forms of lakes. A dispersion form of lakes is generally a liquid food-grade carrier, such as sugar syrup, to which lakes have been homogeneously dispersed at varying levels.” Other carriers, such as glycerin or propylene glycol can be used.
For fat-based systems, lakes may be dispersed into an oil. Applications for oil dispersion include chocolates, compound coatings, icings and cookie fillings.
Chewing gum provides an example of a perfect application for lakes. Dispersing the lake into the gum matrix provides homogenous coloration, despite limited amounts of water that would hinder color development of a dye. During chewing, the color remains locked inside the gum matrix, instead of leaching out into the consumer’s saliva.
Colored noodle products face a similar challenge as chewing gum, with a similar solution. Water-soluble dyes may provide excellent coloration to pasta in a package. However, the color will leach out during boiling, resulting in faded noodles on the plate and oddly tinted water in the pot.
Using lakes to color ice cream mix-ins gives manufacturers more flexibility of addition time and temperature, by eliminating the chance of color bleeding that can occur with mix-ins colored with water-soluble colorants.
The insoluble substrate of alumina hydrate that lends lakes their dispersion characteristics also imparts increased opacity to confections. “The opacity contributed by the lakes enhances elegance of coated confections.” Martin says. “Coated confections colored with lakes are more attractive, with more-even color coverage than coated confections colored with FD&C dyes.”
I think hur-on to something
Almost any product in which complete dispersion is achievable is a candidate for coloration with lakes. However, usage levels for lakes are approximately ten times the level needed for the corresponding FD&C dye. Typical usage rates range from 0.05% to 0.30%, depending on the desired shade and intensity. Product composition—moisture, solids, fat content, etc.—can affect usage levels, but not directly. Martin says that opacity has the greatest impact on usage level. “These items affect the lake usage if they change the opacity,” she says. “The more opacity, the more color one will need to add to achieve a given desired strength and shade.”
The lake’s particle size can also affect the finished product color. A smaller particle thoroughly dispersed in the matrix results in a more intense color due to the increased surface area of the particles.
Speaking from a technical standpoint, developers can apply lakes to any system in which FDA allows colorants and will allow uniform color distribution. There are some arenas in which lakes cannot compete. “They are pigments and are not soluble, so they are not suitable for most beverage systems,” Martin says. “Also, they will become free dye in foods with a pH less than about 4.5 and greater than about 7.5. Acids and alkali both break lakes into their free dye components.”
R. J. Foster has over a decade of experience in research & development and technical service in the food industry. He is a freelance writer specializing in technical communications, and can be reached at askrjfoster@sbcglobal.net.