Knowledge of the use of colorants, color protectors and bleaches

Knowledge of the use of colorants, color protectors and bleaches
01
Colorants
Color and luster are important sensory indicators for evaluating the quality of food;
Whether the color is normal or not is an important basis for judging the quality of food;
Food with pleasing color can win a good first impression.
Colorant is to make the food color and improve the color of food substances.

I. Food and Color
The color of food and its acceptability.
It is the first feeling
It is one of the indicators to judge whether the quality of food is good or bad freshness
The value of food ingredients is determined by their color and luster
However, in food processing, the natural pigments in food will be discolored or faded, so in order to restore or improve the color of food, it is necessary to use coloring agents.
Color and luster give flavor associations. The ability of a food product to be attractive and give a sense of taste in terms of color largely determines the marketability and evaluation. Common colors act on the senses in the following general ways:
Green and blue: give a person a fresh, refreshing feeling, mostly used in alcohol, convenience dishes, beverages and other foods. But there is a raw, cool, sour feeling, so non-vegetable canned food, snacks and pastries, etc. generally do not use these colors.
Red: give people a strong taste of mature and delicious feeling, and more bright and eye-catching, can stimulate the consumer’s desire to buy, so many candies, pastries, etc. are used in this type of color.
Orange: is a mixture of yellow and red color, both red and yellow advantages of the two colors, giving a strong sense of sweetness, maturity and mellowness, beverages and canned food and other foods are used.

Coffee color: it gives a feeling of unique and strong flavor. Coffee, chocolate, beverages, pastries, beer and tea are often used.
Yellow: gives a person the feeling of aroma, ripe and delicious, appetite, baked goods, canned fruits and margarine and other foods are often used.
Second, coloring agent classification
(A) food synthetic coloring
Food synthetic coloring is an artificial chemical synthesis of organic pigments. At present, the world allows the use of synthetic pigments are almost exclusively water-soluble pigments, in addition to their respective color precipitates.
Color precipitation is by water-soluble pigments precipitated in the permitted use of insoluble substrate (usually Al2O3) prepared by the special coloring agent, suitable for a variety of powdered foods, snack foods, gummies, candies (especially with titanium dioxide formulated as a suspension of coated or sliced confectionery) and a variety of pressed food.
China’s permitted use of synthetic food coloring are: amaranth red, carmine, erythrosine, new red, seductive red, lemon yellow, sunset yellow, bright blue, indigo and their respective aluminum precipitates, as well as β-carotene, sodium copper chlorophyll and titanium dioxide.
(ii) Edible natural colors
Edible natural pigments are from natural substances, the use of certain processing methods to obtain organic coloring agents, there are many varieties.
Plant pigments: such as green (chlorophyll), orange (carotene), red or purple (anthocyanin);
Animal pigments: e.g. red pigments in muscle, carotenoids in shrimp and crab skin;
Microbial pigments: e.g. erythroxanthin.
Advantages: security than synthetic pigments, so the recent development is rapid, countries licensed to use the varieties and the amount are increasing.
Disadvantages: pigment content and stability are not as good as synthetic products.
Development trend: Although the use of synthetic products in the permitted range and the amount of use, will not bring harm to human health, but in the reverence for natural and return to nature today, the use of chemicals is declining year by year, and natural coloring agents are becoming more and more popular.

Third, the use of colorants
(I) Blending
Because of the varied requirements of food on the tone, so in order to meet the coloring needs of food production, colorants can be mixed in different proportions to blend the desired tone. 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 the temperature increases, the 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
Since most of the food processing, heat treatment, so the coloring agent is required to have a certain degree of heat resistance. The heat resistance of colorants is related to coexisting substances such as sugar, salt, acid and alkali. When coexisting with the above substances, it will change color and fade.
Lemon yellow, sunset yellow heat resistance is stronger; indigo, carmine heat resistance is weaker.
Most of the general foods are in the acidic range, such as fruit foods, candy, drinks, lactic acid fermented foods and vinegar foods, etc. Colorants may form pigment acids in the acidic environment and easily discolor or precipitate, so the colorants are required to have a certain degree of acid resistance.
The acid resistance of indigo is weak; the acid resistance of lemon yellow and sunset yellow is strong.
Adding alkaline puffing agent cake food, in addition to high-temperature processing, there are alkaline substances, which requires a certain degree of alkaline resistance of the pigment.
Lemon yellow has a strong alkali resistance; carmine has a weak alkali resistance.
Therefore, the coloring agent is required to have better antioxidant properties, anthracene pigment antioxidant is stronger, azo pigments or other pigments are generally weaker, which nature of fruit juices, margarine and so on have a greater impact.
Colorants added to food can be subjected to reduction and fade. This phenomenon can be in the fermented food processing, or in food manufacturing, storage and other processes due to the role of microorganisms and can also be caused by metal containers (iron, aluminum, etc.) and acid reaction, or metal containers and salt potential difference.
In addition, ascorbic acid and sulfites and other additives also have a reducing effect. Anthracene pigments are quite stable, while indigo and azo pigments are unstable.
The use of translucent film packaging food, ultraviolet light can deteriorate the quality of food. The UV resistance of colorants varies considerably depending on the nature of the water used to manufacture the food (pH, hardness, heavy metal ion content, etc.) and the type of substances that coexist with the pigment. Indigo is less UV resistant; lemon yellow and sunset yellow are more UV resistant.
For pickled products, salt resistance is required for colorants due to the high salt used. Lemon yellow in the salt concentration of 20 ° Be above is still more stable; indigo in 1 ~ 2 ° Be that is not stable.
The stability of different colorants to bacteria is different. Lemon yellow, sunset yellow is more resistant to bacteria; indigo is weaker.
Comparison between edible synthetic pigments and edible natural pigments
(I) Synthetic food coloring
In recent years, with the rapid development of the chemical industry, synthetic coloring agents are widely used due to the following advantages:
① bright colors ② stable nature ③ high firmness
③ high firmness ④ arbitrary mixing ⑤ low cost ⑥ easy to use
Due to the current synthetic colorants

Since there is now a great deal of debate on synthetic colorants and regulations are frequently modified in various countries, it is vital to keep track of the use of synthetic colorants in various countries for the food trade.
(ii) Edible Natural Colors
Natural colorants have a long history of use. Natural products give people a sense of security, and there is great interest in natural coloring.
There are over 2,000 species of colored non-toxic plants in nature with a wide variety of colors.
Natural coloring:
① Stable to light, heat and oxidation
② not easily affected by metal ions or other chemicals
③ harmless to the human body
Advantages of consuming natural coloring:
① Generally speaking, the safety is higher than consuming synthetic colorings;
② Some kinds are nutrients themselves (such as -carotene), or have certain pharmacological effects (peanut coat red, mulberry red, etc.);
(iii) The imitation of the color of natural substances and the naturalness of the coloring chromatogram is better.
Disadvantages of eating natural coloring:
① poorer dyeing, firmness, in the processing and circulation process is susceptible to external influences;
② poor color mixing, poor solubility of different pigments, it is difficult to mix any color;
③ product differences. Due to different raw materials, origin or processing methods, the production of the same variety of colorants, in the composition, nature is difficult to be completely consistent. Such as chlorophyll extracted from vegetables and sand from silkworms, in the chromatography of certain differences, the reason lies in the maximum absorption wavelength of the two chlorophyll (lmax) is different.
After extraction, purification and other processing of pigment products, may be in the nature and chemical structure of the change, so the natural products itself does not guarantee absolute safety. Accordingly, our country stipulates:
Toxicological test is not required: no change in the chemical structure during the production process and the concentration of the natural pigments used does not exceed the original state.
Toxicological evaluation is required: natural pigments whose concentration is greater than the original state or whose chemical structure has been changed in the production process.
The pigment products obtained after extraction, purification and other processing may change in nature and chemical structure, so the natural products themselves do not guarantee absolute safety. Accordingly, our country stipulates:
Toxicological test is not required: no change in the chemical structure during the production process and the concentration of the natural pigments used does not exceed the original state.
Toxicological evaluation is required: natural pigments whose concentration is greater than the original state or whose chemical structure has been changed in the production process.