Cotton's Protein Content: Fact Or Fiction?

Cotton is a natural fibre that comes from the cotton plant. It is the most widely produced natural fibre in the world and is frequently spun into thread and used to make soft, breathable textiles. Cotton fibres are made of cellulose, a polymer made of glucose. However, cottonseed, which accounts for about 13% of world oilseed production, contains oil and protein in large quantities. Cottonseed proteins have a high content of ionisable amino acids and have been studied for their potential use in medical applications such as wound dressings.

Cotton fibres are made of cellulose

Cotton is the most widely produced natural fibre in the world. It is a natural cellulose fibre, with cotton fibres made up of 90-94% cellulose.

Cellulose is a polymer made up of glucose, a type of sugar. Glucose is produced in the leaves of the cotton plant through photosynthesis, which uses energy from sunlight to turn carbon dioxide and water into glucose. The glucose molecules are then linked together by enzymes to form cellulose.

Cotton fibres are made up of cellulose, which is a major component of the cell walls of all plant cells. Cotton fibres are essentially the dried-out remains of long and thick cell walls.

Cotton fibres are made up of cellulose, which is a type of carbohydrate. Most animal fibres, in contrast, are made up of proteins. Synthetic fibres, such as nylon and polyester, are made from long chains of hydrocarbons, usually derived from crude oil.

Cotton fibres are composed of cellulose, which is a macromolecule or polymer. The cellulose in cotton is made up of long chains of glucose molecules linked by C-1 to C-4 oxygen bridges, with the elimination of water (glycoside bonds). The repeating unit in the cellulose polymer is anhydro-beta-cellobiose.

The cellulose in cotton differs from wood cellulose in having a higher degree of polymerisation and crystallinity. Cotton cellulose has a higher degree of crystallinity, meaning its fibre molecules are closely packed and parallel to one another. This gives cotton greater strength.

Cotton fibres are held together by hydrogen bonds between the hydroxyl groups of adjacent cellulose molecules. These hydrogen bonds are most prevalent in the parallel, closely packed molecules in the crystalline areas of the fibre. The hydroxyl groups also act as sorption sites for water molecules, allowing cotton to absorb water.

Cotton is not a thermoplastic fibre, so it does not have a glass transition temperature and remains flexible at very low temperatures. At high temperatures, cotton decomposes rather than melts.

Cotton fibres have a unique morphology, with a cuticle, primary wall, winding layer, secondary wall, lumen wall, and lumen. The cuticle is a waxy outer layer that protects the fibre. The primary wall is the original thin cell wall, made up of a network of fine cellulose fibrils. The winding layer is the first layer of secondary thickening, with fibrils aligned at 40 to 70-degree angles to the fibre axis. The secondary wall is the main portion of the fibre, made up of concentric layers of cellulose. The lumen wall separates the secondary wall from the lumen, a hollow canal that runs the length of the fibre.

Cottonseed proteins have potential in human nutrition

Cotton is a plant that has been cultivated in 70 different countries for centuries as a fiber crop. Cottonseed accounts for about 13% of world oilseed production, although oil production accounts for only about 15% of the commercial value of the cottonseed crop. Cottonseed is crushed to extract oil and to produce cake that is chiefly used for ruminant livestock. As it contains gossypol, a toxic compound, this cake cannot be used for human consumption. Cottonseed proteins make up 30–40% w/w of the cottonseed kernel. Other important cottonseed components include lipids, soluble carbohydrates, cellulose, minerals, phytates, and polyphenolic pigments. The protein components are mainly globulins (60%) and albumins (30%), with much lower proportions of prolamins (8.6%) and glutelins (0.5%).

Cottonseed proteins have a high content of ionizable amino acids (aspartic and glutamic acids, arginine, histidine and lysine) and a low content of sulfur amino acids. These proteins are more soluble at a basic pH than at an acidic pH, and have an isoelectric point of around 5. Cottonseed proteins are readily denatured by thermal treatment above 80°C, leading to loss of solubility and nutritional value.

The global cottonseed production in 2019/2020 is estimated to be ~44.84 metric million tons (MMT). Cottonseeds contain 17–22% oil, and after oil extraction, cottonseed meal (CSM) is obtained as a coproduct. CSM has the potential to produce ~10 MMT proteins, which could fulfil the annual protein requirements of more than half a billion people globally. The cottonseed protein fraction contains the highest content of salt-soluble protein (globulins: 33–63.7%), followed by water-soluble (albumins: 20.8–32.2%) and alkali-soluble (glutelins: 9.2–28%) proteins. As evidenced by a recent review, most African and Asian countries have a higher severity of malnutrition and are ranked 90–119 in the Global Hunger Index, 2018. Nevertheless, these are the highest cotton-producing nations of the world, producing more than 1000 tons of cottonseed annually. Hence, the successful and efficient utilization of cottonseed as a protein source could be a game changer in mitigating malnutrition in the most severely affected countries.

Cottonseed proteins have film-forming properties

Cotton is a plant that has been cultivated in 70 different countries for centuries, primarily for its fibres. Cottonseed, which accounts for about 13% of world oilseed production, is also a valuable commodity. Cottonseed proteins make up 30–40% w/w of the cottonseed kernel and have

Cotton fibres are not made of protein

Cotton is a natural fiber that comes from the cotton plant. It is the most widely produced natural fiber on Earth. Cotton fibers are made of cellulose, which is a type of carbohydrate. Cotton fibers are not made of protein.

Cotton is a soft fiber that grows around the seeds of the cotton plant. It is frequently spun into thread and used to make soft and breathable textiles. Cotton is a natural fiber, and its fibers are the purest form of cellulose, which is nature's most abundant polymer.

Cellulose is a polymer made of glucose, which is produced through photosynthesis in the leaves of the cotton plant. The glucose molecules are linked together by enzymes, forming the cell walls of the cotton plant. Cotton fibers are essentially dried-out remains of these extraordinarily long and thick cell walls.

While cotton fibers themselves do not contain protein, cottonseed, which accounts for about 13% of world oilseed production, is rich in protein. Cottonseed proteins constitute 30-40% of the cottonseed kernel and are mainly composed of globulins and albumins. However, cottonseed is not suitable for human consumption due to the presence of gossypol, a toxic compound.

In summary, cotton fibers are not made of protein. They are composed of cellulose, a type of carbohydrate, and are derived from the cotton plant. Cottonseed, on the other hand, contains a significant amount of protein but is not fit for human consumption due to the presence of toxic substances.

Cotton has protein interactions with wound dressings

Cotton is a natural fiber that comes from the seed coat of cotton plants. It is composed primarily of cellulose, a type of carbohydrate, with smaller amounts of water, protoplasm, pectins, waxes, fatty substances, and mineral salts. While cotton itself does not contain proteins, it does interact with proteins when used in wound dressings.

Cotton is widely used as a wound dressing material due to its softness, low cost, and ability to absorb moisture. However, its hydrophilic nature can also cause issues, as it may absorb water from the outside environment, leading to inconvenience for patients who need to avoid getting the dressing wet. Additionally, the hydrophilic nature of cotton provides a suitable environment for the growth of pathogenic bacteria, potentially leading to wound infections and impeding the healing process.

To address these challenges, researchers have been working on modifying cotton dressings to enhance their antimicrobial and healing-promoting properties. One approach is to create a multilayer electroactive composite cotton dressing, such as Ag/Zn@Cotton/Paraffin, which has been shown to have antibacterial activity against S. aureus and E. coli. This dressing uses electrical stimulation (ES) to promote wound healing by generating an electric field when it comes into contact with wound exudate.

Another area of exploration is the interaction between cotton and specific proteins in wound fluid, such as albumin and elastase. Albumin is the most prevalent protein in wound fluid, and it can bind significantly to the fibers of wound dressings, especially in highly to moderately exudative wounds. Elastase, on the other hand, is over-expressed in chronic non-healing wounds, where it interferes with the normal healing process by digesting tissue and growth factors. By understanding how these proteins interact with cotton fibers, researchers can design more effective wound dressings, particularly for chronic wounds.

In summary, while cotton itself does not contain proteins, its interactions with proteins are important in the context of wound care and wound dressing development. These protein interactions can impact the effectiveness of cotton dressings and guide the creation of modified cotton dressings with enhanced antimicrobial and healing properties.

Frequently asked questions