World Cotton Day | Is cotton a flower? Only white? Only for quilts? Things you don’t know about cotton

In 2019, four cotton producing countries in sub-Saharan Africa, namely Benin, Burkina Faso, Chad and Mali, proposed to the WTO to designate October 7 as World Cotton Day.

Is cotton a flower?

Cotton is a plant of the Malvaceae family, the genus Gossypium, native to subtropical regions, and is heat-loving, light-loving, and drought-tolerant. The cotton we usually refer to is not the real "flower", but the fruit of cotton.

When the real cotton flower first blooms, it is milky white, and then gradually turns pink, red, purple, and the color becomes darker and darker. It is a typical flower that changes color. Since each flower may bloom at different times, there may be several different colors of flowers on the same cotton plant at the same time. Other flowers that change color like cotton include hibiscus, morning glory, etc.

After the cotton flower withers, it will produce small fruits called cotton bolls. Because it looks like a peach, it is also called cotton boll. Inside the cotton boll is a cotton seed. The cotton seed has fuzz on its surface, filling the cotton boll. When the cotton boll matures, it splits open, revealing the fuzz inside. This is what we usually call cotton.

Is cotton only white?

Nowadays, most common cotton is white, but in fact, there are also colored cotton in nature, and the ancestors of cotton were also colorful. However, due to the small yield and short fiber length of colored cotton, it does not meet the requirements of the textile industry, and colored cotton is not as easy to dye as white cotton, so it has not been widely planted and promoted.

However, colored cotton can reduce the printing and dyeing steps in the textile process, reduce pollution to the environment, and also reduce the potential harm of chemical dyes to human health.

As people pay more and more attention to environmental and health issues, the world's major cotton producing countries have stepped up their research and development of colored cotton. Scientists have cultivated new varieties of colored cotton through gene transfer technology, which has significantly improved the quality of colored cotton.

Currently, brown and green colored cotton has been used in actual textile and production.

Not long ago, the cotton molecular genetic improvement innovation team of the Cotton Research Institute of the Chinese Academy of Agricultural Sciences successfully enriched betalain in cotton fibers and created pink cotton fibers, providing a new idea for using genetic engineering methods to cultivate multiple types of colored fiber cotton. The study first optimized the codons of three key genes related to betalain synthesis, and obtained a new cotton material rich in betalain using the cotton variety "China Cotton Research Institute 49" as the receptor. This study was the first to introduce betalain into cotton and stably express it. It was a preliminary exploration of synthetic biology research using cotton as a base organism, laying the foundation for the creation of new types of colored cotton.

What else can cotton be used for besides filling quilts?

01Cotton flowers can be used to make honey

Cotton honey is formed by bees collecting nectar secreted by nectar glands in cotton leaf veins, bracts and flowers. Unlike other honeys, cotton honey does not only come from open buds.

Cotton is a special nectar plant. This is because there are large and small veins distributed in the leaves of cotton. There is a nectar gland under the main vein, and there are also nectar glands under the bracts. Before flowering, the nectar glands under the veins will start to secrete honeydew first, followed by the nectar glands under the bracts. During this period, the honey collected by bees is nectar, and when the cotton blooms, the honey collected is cotton nectar. There is a difference in quality between the two.

02 Cotton wool can be made into "pearls"

In addition to being made into clothing for warmth and protection from the cold, cotton wool can be compressed to make cotton pearls. After being plastic-sealed, it is waterproof and can be artificially dyed to meet the needs of different types.

Since the inside is a compressed cotton ball, cotton pearls are very light and easy to wear compared to ordinary pearls. Even if jewelry designers use extremely large cotton pearls to design more exaggerated jewelry shapes, they don’t have to worry about the weight when wearing them. The rough grainy and textured effect on the surface, after being plated with a layer of charming pearlescent layer, has a more vintage and retro feel.

04Cotton linter is an important strategic material

After ginning, there are still short fibers on the cotton seeds (wool seeds). These short fibers are stripped off with a linting machine, which is cotton linter. Cotton linter is an important raw material for light and chemical industries such as national defense, textiles, chemical fibers, and papermaking, and is an important strategic material.

The first-grade cotton linters are 12-16mm long and can be used to produce textiles such as cotton blankets and fleece clothes, as well as high-grade paper such as wax paper and coated paper. The first-grade cotton linters used in banknote printing paper are the first-grade cotton linters.

The cotton content of RMB is 95%. The raw materials are produced in Shihezi, Xinjiang, and the highest quality local cotton linters are used. Cotton linters have long fibers, and with a small amount of plant pulp, the printing paper is tougher, thicker, and has a strong coloring power. It is precisely because of this that RMB has the characteristics of not being rotten in water, wear-resistant and corrosion-resistant, and can be stored for a very long time. Moreover, the paper is tough and fold-resistant, and it will make a louder sound than ordinary paper when shaken.

Type II linters, 3-12 mm in size, can be made into cellulose nitrate, which is used to produce smokeless powder or solid fuel for rockets.

The three types of short fibers below 3 mm can be used to produce viscose fiber and acetate fiber.

05Cotton seeds can be made into skin care products

Cottonseed oil refined from cotton seeds is not only used in the food industry, but it is also an important active ingredient in skin care products.

Cottonseed oil is rich in high-quality vitamins, fatty acids and sterols. Vitamin E has a strong antioxidant effect. Every 100g of cottonseed oil contains 86.45mg of vitamin E, making it a star antioxidant product in nature. Vitamin F can prevent the harmful effects of X-rays to a certain extent, and prevent and treat acne.

At the same time, unsaturated fatty acids have moisturizing properties, which can prevent dry skin and dehydration, and maintain skin elasticity. Sterols can help delay aging, promote metabolism, and regulate human hormone levels. These ingredients are combined in perfect proportions and complement each other, making cottonseed oil unique in skin care properties.

The kernel and seed coat of cotton seeds also contain high levels of gossypol, a polyphenol compound common to all cotton plants. Free gossypol is toxic to humans, which is why crude cottonseed oil is forbidden. However, in medicine, it can be used to produce drugs for treating diseases such as uterine fibroids.

06Cotton waste: making biodegradable plastic

When cotton fibers are stripped from cotton seeds using cotton gins, a lot of cotton lint waste is created. Much of it is simply burned or put into landfills.

Researchers at Deakin University in Australia have developed a system that uses cheap, environmentally friendly chemicals to dissolve cotton linter fibers and other waste. The resulting liquid organic polymer is then used to make plastic films.

The material is biodegradable and could be used in the cotton farming industry, such as wrapping bales or packaging seeds and fertilizers. It could even become part of a full-cycle agricultural process. The plastic film is cheaper to manufacture than other similar petroleum-based products.

In addition, scientists from the National University of Singapore have also discovered a new use for cotton waste, which can be converted into insulating and absorbent aerogel.

Comprehensive sources: China Science and Technology Museum, CCTV News Weibo, Yangtze Evening News, China Biotechnology Network, BTV News, Science, etc.