Use of coloring agents
(I) Blending
Since food products have ever-changing requirements for color tones, colorants can be mixed and blended in different proportions to meet the coloring needs of food production. Theoretically, the three basic colors of red, yellow and blue (ternary colors) can be blended to produce a variety of different shades (three-color principle).
Precautions when mixing colorants:
When coloring, do not use colorant powder directly, but use solvents to formulate (the main consideration is its uniform distribution in the food).
When preparing, weigh accurately, dissolve the colorant, and then dilute it to a solution of 1~10% concentration for use. If water is used as the solvent, distilled or deionized water is preferred.
Prepare the solution without metal utensils as far as possible. Do not use more than the standard amount, so as not to avoid the food too brightly colored and unnatural.
Use as you prepare. Because the coloring solution is left for a long time, the light is not stable enough coloring agent will occur discoloration phenomenon, and higher temperatures when the coloring agent solution water evaporation speed up, resulting in increased pigment concentration and produce a “concentration effect”. Such as carmine aqueous solution will become black after long-term placement.
(B) solvent and solubility
In food production, the most important solvents are water, alcohol (ethanol, glycerol) and vegetable oil. The pigments normally used, with the exception of color pigments and β-carotene, are water soluble.
Factors affecting the solubility of pigments are:
1, temperature. Generally temperature increases, solubility increases;
2, pH. pH decreases, colorants have a tendency to form pigment acids and make the solubility decrease;
3, water hardness. High water hardness tends to produce insoluble color precipitate;
4, salts. When the concentration of salts is high, salt precipitation can occur;
5, the nature of the solvent
Specific performance:
Various pigments dissolved in different solvents, can produce different shades and intensity, especially when using two or several kinds of pigment color combination, the situation is more significant.
For example, a certain proportion of red, yellow, blue mixture, in aqueous solution in the hue of yellow, while in 50% alcohol is more reddish hue. All kinds of alcohol due to the different alcohol content, the dissolved color tone is also different, so it is necessary to according to its alcohol content and the intensity of the tone of the need to spell color.
Food in the coloring is wet, when the water evaporates, gradually drying, the pigment will also be more concentrated in the surface layer, resulting in the so-called “concentrated impact”, especially when this food and the affinity of the pigment is lower, more significant.
Color combination of various pigments in the stability of sunlight is different, fading speed is also different, such as indigo fading faster, lemon yellow is not easy to fade. Because of the many factors affecting the color tone, in the application of the specific practice must be flexible.
(C) Adhesion
There are two kinds of coloring: pigment dissolved or dispersed in liquid or sauce-like food; stained on the surface of the food.
The staining of the same pigment on different dyeing substrates is different, and the staining of different pigments on the same dyeing substrate is not the same, such as erythrosine on the protein substrate staining is better, while lemon yellow is worse.
(D) Firmness
Firmness is the color stability of the dyed material or pigment resistance to changes in the surrounding environment. Firmness of the pigment is an important indicator of the quality of the pigment.
Firmness depends mainly on the chemical nature of the pigment and the nature of the dyed material. However, the use of improper pigment varieties or improper operation is also easy to reduce the firmness. Firmness is a comprehensive standard, with the following indicators.
1、Heat resistance 2、Acid resistance
3, alkali resistance 4, oxidation resistance
5、Reducibility 6、Ultraviolet (sunlight) resistance
7、Salt resistance 8、Bacteria resistance
