Table 514

Contrasting Properties of Lakes and Dyes

Properties

Lakes

Dyes

Solubility

Insoluble in most solvents

Soluble in water, propylene glycol, glycerin Dissolved in material to be colored Around 90% 0.01-0.05% 10-200 mesh

Variable but good in general

Method of imparting coloring By dispersion

Content of pure dye Rate of use Particle size

Stability (light and heat) Coloring strength Shade

Usually 0.5-30 |im Better than dyes

Not proportional to pure dye content Proportional to dye content Varies with pure dye content Constant

Constant

Source: Adapted from Stern (1988).22

formation is pressed and washed with water to a predetermined salt concentration. In the laking process, FD&C dye is dissolved and alumina hydrated with water. Lake is formed by dye precipitation onto the substrate by effect of the addition of the aluminum salt solution. The product is collected, dried, and milled. The tinctorial strength of lakes improves with smaller particle size and increasing number of particles. However, lake particles tend to coalesce to the detriment of product appearance. This problem is minimized by using dispersions.22

The FDA has established several specifications for lakes prepared from previously certified colors: soluble chlorides and sulfates (as sodium salts), not more than 2.0%; inorganic matter, insoluble HCl, not more than 0.5%; etc.22

A lake is named by combining the name of the dye used in its preparation and the words aluminum and lake: for example, FD&C blue No. 1 aluminum lake. The properties of lakes contrast to those of dyes (Table 5.14).22 Lakes are used to color the outside of the product (such as an opaque candy) or a fat-based product (such as chocolate). Dispersions of lakes are available in different carriers, which are related to their practical application: oil bases for coatings, crackers, snack foods, and wax products; propylene glycol or glycerin for bubble gums, hard candies, sugar coatings, and sugar syrups (the most popular for candies and gums). Lakes are widely used in beverages, bakery products, icings, confectionery coatings, gelatin specialties, ice cream, sherbet, hard candy, and pet foods. Lakes are also used to produce the bright attractive colors of chewing gum by eliminating dye staining. As can be observed, the spectrum of uses of FD&C lakes is as diverse as the dyes.223233

As can be deduced, the selection of a product (lakes or dyes) and its presentation is of huge importance to the quality of the final product. In addition, formulators have introduced other strategies to improve colors stability, such as the encapsulation process, the introduction of a protective coating that isolates two regions in the product (e.g., candy with a high acid center), and the introduction of other additives (e.g., antioxidants).

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