Introduction to Common Natural Dyes: What are They?

The utilization of natural food dyes is witnessing a surge in popularity. People are getting concerned about their health more, which is why we are starting to focus on the topic of food coloring.

At present, food coloring is broadly divided into two categories: one is artificial chemical food synthetic pigments, most of these pigments are azo types of compounds, the human body has certain toxic side effects; the other is derived from natural plant roots, stems, leaves, flowers, fruits and animals, microorganisms and other edible pigments. These naturally sourced colorants are commonly referred to as "Natural Food Dyes."

Let us explore some of the common natural food dyes:

1. Chlorophyll:

It is a diol ester condensed from chlorophyllic acid, chlorophyll alcohol and methanol, which is a porphyrin compound that binds four pyrrole nuclei to form four pyrrole rings, and its chelating central metal ion is the Mg ion. Studies have shown that chlorophyll in plants mainly contains chlorophyll a and chlorophyll b. They are insoluble in water, but soluble in organic solvents such as alcohol, acetone, and petroleum ether.

Chlorophyll is abundantly present in the leaves of higher plants, fruits, and algae, and constitutes a pivotal component of plant chloroplasts. Within organisms, it forms essential bonds with proteins and plays a crucial role in imparting green coloration to most leafy vegetables and immature fruits. Furthermore, chlorophyll has been attributed with various biological benefits, including its role in blood supplementation, hematopoiesis promotion, cellular activation, and antimicrobial and anti-inflammatory properties. Recent scientific reports have even discovered its potential to restrain the production of cancer cells.

Foods rich in chlorophyll include: kale, alfalfa sprouts, spinach, broccoli, and lettuce, among others.

2. Hemoglobin:

Hemoglobin acts as the cofactor for oxygen transport in the blood and muscle chromoprotein. It represents a critical component of animal-based foods and is notably influential in the coloration of meat. Upon strong oxidation, hemoglobin can exhibit a green hue, explaining the phenomenon of meat turning green during extended storage. Heme, a component of hemoglobin, has demonstrated remarkable efficacy in the treatment of anemia, particularly iron-deficiency anemia.

Heme-rich foods encompass animal-based products such as pork, beef, animal liver, and animal blood.

3. Carotenoids:

Carotenoids constitute a broad category encompassing numerous isomers and derivatives found in plants. They are characterized by their vivid colors and are aptly named for their initial discovery in carrots.

Scientific investigations have unveiled the potential health benefits of increased carotenoid intake, including the reduction of age-related conditions such as senile prostatism and retinal macular degeneration. Consequently, natural carotenoids have received approval for use as anti-radiation health supplements. Diverse molecular structures characterize different carotenoids, with over 600 identified by the end of the 20th century.

Carotenoid-rich foods include: carrots, pumpkins, tomatoes, citrus fruits, corn, shrimp, crab, and various fresh fish species.

4. Anthocyanins:

Anthocyanins belong to the flower pigment, in the form of glycosides (anthocyanosises) in the cytosol of plants and are the main cause of the coloration of plant flowers, leaves, stems, and fruits. The red water-soluble pigments contained in fruits and vegetables are mainly anthocyanins, such as the purple color of eggplant, the red color of strawberries the purple-red color of grapes, etc., which is also the main component of flower color. Anthocyanins consist of a glycosidic ligand and sugar in their structural formula and are generally water-soluble.

Anthocyanins are also prevalent in various flower species. Their chemical properties exhibit considerable instability, with color variations occurring in response to changes in pH, transitioning from red at pH 7 or below, to purple at pH 8.5, and violet-blue at pH 11 or greater. Exposure to oxygen, light, or elevated temperatures can induce browning in foods rich in anthocyanins, and care should be taken to prevent discoloration caused by contact with iron during food processing.

Foods containing anthocyanins: purple potatoes, black rice, purple corn, purple kale, eggplants, perilla leaves, carrots, and beets.

In conclusion

The visual appeal of food, characterized by harmonious and vibrant colors, can significantly enhance the sensory experience and appetite stimulation. It is important to emphasize that natural food colors offer a higher level of safety compared to synthetic alternatives. Therefore, a prudent approach to food production involves a judicious selection of natural colorants, aligning with both visual aesthetics and nutritional science.