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  • 8 March 2023

12. Hemp: A multi-purpose plant

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  • Abstract
    Hemp (Cannabis with THC<0.3%) has a large variety of applications ranging from textile to building material. Did you know that hemp fibers are one of the strongest natural fibers? They are also sustainable and versatile! Harvested via a process called “retting”, they can have a high flexibility or be very stiff depending on the organization of the layers inside the fibers. Hemp fibers are very durable, breathable, hypoallergenic and able to absorb moisture. Some applications of hemp fibers include paper production, concrete-like material (hempcrete), textiles such as towels and clothes and insulation material. Cultivation of hemp is very sustainable because of the natural resistance of hemp to mold and other pests. Other parts of hemp also have many applications. Hemp oil can be used for cooking but also for biofuel production! Hemp seeds instead can be eaten raw or cooked and are rich in nutrients. Overall, hemp is a multi-purpose plant with a versatile use in industry, and we are recently rediscovering most of its application!

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The Daily Adrian

12. Hemp: A multi-purpose plant
March 8th, 2023

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Whenever we think of Cannabis, the first thing that comes to mind are its psychoactive effects. However, Cannabis is a multi-purpose plant, and its applications go far beyond the recreational and medical use of the plant flowers (newsletter 11). Many parts of Cannabis, or rather its less psychoactive form known as hemp, can in fact be used to create textiles, cosmetics, concrete-like material and so much more! In this article we’ll have a short look at some of these applications.

Industrial Hemp

Hemp, also known as industrial hemp, is a variety of Cannabis sativa with no psychoactive properties and low amounts of THC (<0.3%) [1]. While this may sound disappointing for recreational users of Cannabis at first, ancient humans were able to grow and harvest hemp fibers for clothes, ropes and fishing nets already 10000 years ago, with the oldest evidence found in China [2]. 

Hemp fibers

Hemp fibers are still considered today one of the strongest natural bast fibers and are progressively gaining popularity in recent times as a sustainable alternative to synthetic fibers [3]. Hemp fibers are mostly composed of cellulose, a polysaccharide also present in the cell wall of plants, as well as other compounds such as hemicellulose, lignin, pectin, and wax [4]. The fibers are organized in a multi-layered structure, and depending on the microstucture of the layers, hemp fibers can have a high flexibility or be as still as glass fibers. This makes hemp fibers very versatile in its applications [3, 4, 5]. They are currently used in industry to produce products such as clothes, paper, fiberboard and animal bedding [3,4,5].

To extract hemp fibers, the stems of the hemp plant are cut down and left to dry. Once dried, the fibers are separated from the stems in a process called “retting” [4,5,6]. This involves soaking the stems in water to loosen the fibers via the action of fungi, bacteria and other microorganisms. Then, the stems are separated and cleaned and ready to be processed! Once the fibers are extracted, they can be used to make a variety of products. The long, strong fibers are often used for reinforcement in building materials. The soft fibers instead are more used for textiles and paper [4,6]. 

Hemp fibers have numerous advantages over other types of fibers. Studies have shown that hemp fibers can be three times stronger than cotton fibers [4,5,6], making them a great choice for clothing and textiles that require high durability such as boots, jackets, sportswear and work clothes. Also, unlike many synthetic fibers, hemp fibers are very breathable and hypoallergenic, which means that hemp-made clothing is great for warmer climates and for people who can have allergic skin reactions. In addition, hemp is also very good at absorbing moisture. It is estimated that hemp fibers can absorb up to 20% of their weight in moisture [7]. This means that hemp has good properties for the production of textiles that require high absorbency, like towels and bathrobes. The high strength of hemp fibers also reflects on hemp paper, which is more durable than traditional paper made from trees. For construction instead, the high stiffness of hemp fibers has been used to produce natural insulation material and hempcrete, a hemp-based building material with very similar properties as concrete [4,7].

Lastly, one of the most significant benefits of hemp fibers is their sustainability when compared to other textile crops. Hemp is a fast-growing plant with a natural resistance to mold, meaning that its cultivation requires a very low amount of pesticides, herbicides, and fertilizers to grow [1,3,4]. Additionally, hemp fibers are biodegradable, making hemp an excellent choice for individuals and companies that aim to reduce their environmental impact. 

Hemp seeds

Hemp seeds and hemp-derived food products have also gained popularity in recent years. Hemp seeds are a rich source of protein, fats, fiber, and various minerals such as magnesium, zinc, and iron. Hemp seeds can be eaten raw, roasted, or ground into other products like flour (used for pasta, bread and cakes) and protein powders, which can be added to smoothies, baked goods, and other recipes [7]. In addition, hemp milk can be made by blending hemp seeds and water, and it is a good non-dairy source of omega-3 fatty acids, protein, and other nutrients! Lastly, by blending hemp seeds and oil into a spreadable paste it is possible to create hemp butter, a vegan alternative to dairy butter [7].

Hemp oil

Hemp oil is made by pressing hemp seeds to extract the oil. It can be used both as an ingredient in cooking and baking [8], but it can also be found in various health and beauty products such as skin creams and lotions. When consumed, hemp oil has been shown to be a rich source of essential fatty acids, particularly omega-3 and omega-6, which are important for maintaining cardiovascular health and cognitive function. Some recent studies are also testing hemp oil as a potential biofuel , and while these research are still in early stages, results are promising due to the high yield of hemp in comparison to other crops used for fuel production! [9] 

But if hemp is so versatile, why are we not using it so much?

Well, this is a simple question with a complicated answer. As a matter of fact, hemp products were popular a few centuries ago. Notable names such as George Washington, Thomas Jefferson and King Henry VIII of England were known to cultivate hemp to make clothes, ropes and construction material [10]. Also, during World War II, when other sources of fibers and textiles were limited across Europe, many countries increased their production of industrial hemp [10]. However, due to historical and political developments around the globe (newsletter 2), hemp cultivation was restricted as all Cannabis variants were classified as illegal in many countries [2, 10]. Most of the products made from hemp were substituted with other crops with similar properties, such as cotton, jute and milkweed [4,10,11]. In recent years, there has been a renewed interest in industrial hemp in both Europe and North America, with some countries legalizing its cultivation and production for industrial and commercial purposes. For example, France is currently the largest producer of industrial hemp in Europe, followed by the Netherlands, Germany, and the United Kingdom [10,11]. Also, Cannabis legalization in many US states is also setting the ground for easier access to cannabis and hemp cultivation [10,11].

Overall, there are many benefits of using hemp in industry, and as more people and companies become aware of these benefits, we will probably see an increase in the use of hemp products in the near future.

Sources

  1. Andre, C. M., Hausman, J.-F. & Guerriero, G. Cannabis sativa: The plant of the thousand and one molecules. Frontiers in Plant Science 7, (2016). 
  2. Charitos, I. The cannabis spread throughout the continents and its therapeutic use in history. Endocrine, Metabolic & Immune Disorders – Drug Targets 21, 407–417 (2021). 
  3. Zhao, X. et al. Industrial hemp—an old but versatile bast fiber crop. Journal of Natural Fibers 19, 6269–6282 (2021). 
  4. Manaia, J. P., Manaia, A. T. & Rodriges, L. Industrial hemp fibers: An overview. Fibers 7, 106 (2019). 
  5. Belwal, T. & Belwal, N. C. Revolutionizing the potential of hemp and its products in changing the global economy. (Springer, 2022).
  6. Liu, M. et al. Effect of harvest time and field retting duration on the chemical composition, morphology and mechanical properties of hemp fibers. Industrial Crops and Products 69, 29–39 (2015). 
  7. Novakovic, M., Milanovic, J., Grujic, D. & Stankovic, S. Liquid transfer properties of textile fabrics as a function of moisture content. Chemical Industry 74, 119–132 (2020). 
  8. Zając, M. et al. The quality of pork loaves with the addition of hemp seeds, de-hulled hemp seeds, hemp protein and hemp flour. LWT 105, 190–199 (2019). 
  9. Ji, A., Jia, L., Kumar, D. & Yoo, C. G. Recent advancements in biological conversion of industrial hemp for biofuel and value-added products. Fermentation 7, 6 (2021).
  10. Deitch, R. Hemp: American history revisited: The plant with a divided history. (Algora Pub., 2003).
  11. Belwal, T. & Belwal, N. C. Revolutionizing the potential of hemp and its products in changing the global economy. (Springer, 2022).
Different uses of hemp. Shows hemp being used for medicine, cosmetics, food, paint, ink, clothes, biofuel and paper.

Sources

  1. Andre, C. M., Hausman, J.-F. & Guerriero, G. Cannabis sativa: The plant of the thousand and one molecules. Frontiers in Plant Science 7, (2016). 
  2. Charitos, I. The cannabis spread throughout the continents and its therapeutic use in history. Endocrine, Metabolic & Immune Disorders – Drug Targets 21, 407–417 (2021). 
  3. Zhao, X. et al. Industrial hemp—an old but versatile bast fiber crop. Journal of Natural Fibers 19, 6269–6282 (2021). 
  4. Manaia, J. P., Manaia, A. T. & Rodriges, L. Industrial hemp fibers: An overview. Fibers 7, 106 (2019). 
  5. Belwal, T. & Belwal, N. C. Revolutionizing the potential of hemp and its products in changing the global economy. (Springer, 2022).
  6. Liu, M. et al. Effect of harvest time and field retting duration on the chemical composition, morphology and mechanical properties of hemp fibers. Industrial Crops and Products 69, 29–39 (2015). 
  7. Novakovic, M., Milanovic, J., Grujic, D. & Stankovic, S. Liquid transfer properties of textile fabrics as a function of moisture content. Chemical Industry 74, 119–132 (2020). 
  8. Zając, M. et al. The quality of pork loaves with the addition of hemp seeds, de-hulled hemp seeds, hemp protein and hemp flour. LWT 105, 190–199 (2019). 
  9. Ji, A., Jia, L., Kumar, D. & Yoo, C. G. Recent advancements in biological conversion of industrial hemp for biofuel and value-added products. Fermentation 7, 6 (2021).
  10. Deitch, R. Hemp: American history revisited: The plant with a divided history. (Algora Pub., 2003).
  11. Belwal, T. & Belwal, N. C. Revolutionizing the potential of hemp and its products in changing the global economy. (Springer, 2022).
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