Post-harvest processing is often a neglected part of the hemp production supply chain. Think about it, when you talk about hemp, what’s the first thing that crosses your mind? For many people, it’s the plant’s versatile applications or its sustainability that come to mind.
Nevertheless, post-harvest processing is critical to the many hemp innovations across various industries. Without it, many of the plant’s versatile applications wouldn’t be possible.
The 6 Steps of Industrial Hemp Processing
Whether you’re processing hemp for CBD extraction or other industrial uses, the following post-harvest industrial hemp processing steps are required:
1. Preparing Raw Materials
Proper hemp drying after a harvest can improve the quality of the final product. Hemp should be dried quickly, cleanly, and with as little damage as possible. If it dries too slowly, gets contaminated with fungi, or stored in a poorly ventilated room, it may be rendered unsuitable for human use. To help you accelerate drying of large-scale hemp harvests, consider investing in an industrial hemp dryer.
Regardless of the end product, industrial hemp processing requires few chemicals. However, processing might involve blending hemp fiber with other materials such as resins or synthetic fibers, depending on the end product.
When making hemp paper, chemicals such as sulfur compounds or sodium hydroxide may be mixed with hemp fibers to get rid of the natural glue components.
2. Seed Processing
The hemp seeds used for oil extraction are dried and cleaned before processing. Oil from hemp seed is extracted through mechanical cold pressing, which involves using a mechanical expeller in a nitrogen-rich atmosphere. During this process, the degree of protection from light, heat, and oxygen determines the shelf life of the resulting oil – as well as its taste.
In addition to mechanical cold pressing, solvent extraction methods for extracting oil from hemp seeds are also quite popular. These methods result in higher yields and use liquid carbon dioxide, ethanol, or butane as the solvents. If the oil is being extracted for cosmetic purposes through solvent extraction methods, extra steps may be required to deodorize and refine it.
3. Fiber Processing
Hemp grown for fiber is harvested when the plants hit the growth stage between early bloom and seed set. When harvesting, you need to be careful not to damage the stalks.
With your harvest ready, separating the various parts of the plant’s stem follows. This requires a machine known as a decorticator, which separates the fibrous part of the hemp plant from the rest of the stem. To make this process easier, retting may be necessary to soften and isolate the fiber before decortication.
There are several ways to carry out retting, each with varying cost, time, and quality implications:
- Water retting: Involves immersing the plant fiber in water to soften it.
- Field/dew retting: Utilizes environmental moisture/dew to soften the hemp plant fiber over several weeks.
- Chemical retting: Involves using chemicals to fast track the process of fiber separation.
- Green retting: Separates the various components of the hemp plant through a mechanical process.
Once the fiber is retted, it must be dried to reduce the moisture content to the 10%-15% range, which paves the way for further processing.
Some of the modern decorticators can also work with freshly harvested hemp and can be used to remove gums and resins from the fiber. Keep in mind that if hemp is intended to be used for CBD extraction, you have to remove the flower heads before fiber processing.
4. Paper Making
Hemp paper production utilizes the bast fibers of the hemp plant. The process begins with putting bast fibers into a spherical tank known as a digester, which contains chemicals and water.
The mixture is then pressurized under high temperatures for several hours to separate the fibers from each other. Afterward, the fibers are washed with excess water to remove extracted binding components like pectin, as well as chemical residues.
Once clean, the fibers move on to a machine known as a Hollander beater, which has a large tub fitted with a wheel that revolves on a horizontal axis. They stay in the beater for about 12 hours, during which they’re cut into the optimal length and given the surface roughness required for proper bonding.
This step may sometimes involve adding bleaching agents. (Alternatively, you can bleach the fibers in a separate tank.) Once bleached, the pulp can be pumped to the papermaking machine or dried and transported to a paper mill if the facility is in a separate location.
5. Recycling Hemp Byproducts
Industrial hemp processing has minimal waste. The core fiber is used to make construction materials, animal bedding, or paper. Any of the core fiber left after making these items is recycled.
Recycling the core fiber removes hemp dust, which can be used to create the hemp pellets used for biomass extraction. Some hemp processors have biomass extraction facilities on-site, while others choose to sell the byproducts to biofuel companies.
The small chips and dirt of the hemp fiber core are high in nutrients and can also be used as soil additives.
6. Quality Checks in Industrial Hemp Processing
Once processed, hemp fibers must be tested for tensile strength, color, and fiber diameter (also known as fineness). Moisture content is also checked and recorded throughout the various stages of production and processing.
In addition to these quality controls, industrial hemp processing companies must abide by state and federal regulations relating to growing and producing hemp and derived products. Among these is the THC content provision, which limits the dry weight THC content to 0.3%.
Learn More About Industrial Hemp Processing
Industrial hemp’s sustainability and environment-friendly status don’t end with its versatile uses across multiple industries, it also manifests in its manufacturing process.
Whether it’s for oil or fiber extraction, processing industrial hemp requires relatively fewer chemicals and resources compared to other alternatives. Also, hemp processing doesn’t produce much waste since every part of the plant is recycled and put to good use.
With such accolades, hemp fits the bill when it comes to eco-friendly and sustainable plant resources, and has the potential to steer the world toward healthier living, sustainable manufacturing, and responsible industrial production.