How Is Flaxseed Hull Processed? – A Detailed Processing Workflow

The production of flaxseed hull is a highly specialized and multi-step mechanical process that ensures efficient separation of the hull from the kernel while preserving the chemical integrity of both fractions. Below is a detailed overview of the industrial procedure:

Step-by-Step Process:

1. Raw Material Cleaning

   • Multiple-stage cleaning removes dust, stones, metal, and light impurities using magnetic separators, vibrating screens, and gravity tables.

   • Ensures purity before thermal or mechanical processing.

2. Segmented Microwave Drying

   • Controlled low-temperature microwave drying gently reduces the moisture content of flaxseed (typically to 6–8%), enhancing brittleness for effective dehulling.

   • Preserves sensitive compounds like lignans and mucilage gum.

3. Impact Dehulling

   • Mechanical impact forces break the seed coat using rotor-based dehullers.

   • Designed to crack shells without damaging the kernel.

4. Air Separation and Grading

   • Air classifiers separate lighter hulls from heavier kernels using aerodynamic principles.

   • Fine and coarse hull particles are then graded through a multi-layer gravity screening system.

5. Color Sorting and Electrostatic Separation

   • Optical sorters remove any discolored or residual kernel fragments.

   • Electrostatic air separators refine purity by leveraging charge differences between hull and kernel particles.

6. Packaging

   • The final flaxseed hull is cooled, stabilized, and packaged into 25kg bags or bulk ton bags based on buyer requirements.

This process ensures ≥98% purity in hull product and is optimized for consistent large-scale supply.

Applications of Flaxseed Hull in Industrial Production

Flaxseed hull is a value-added functional raw material in the following sectors:

1. Flaxseed Gum Extraction

• The mucilage in flaxseed hull contains arabinoxylans and rhamnogalacturonans, water-soluble polysaccharides used in:

  • Natural thickening agents

  • Vegan hydrocolloids

  • Functional food stabilizers

• Basic Process:

  • Soaking → Enzymatic extraction → Centrifugation → Filtration → Vacuum drying → Powder milling

2. Lignan-Rich Powder (SDG Extraction)

• Hulls are the richest source of SDG lignan, which exhibits antioxidant, estrogenic, and cardiovascular benefits (Adolphe et al., 2010).

• Used in:

  • Dietary supplements

  • Cancer-prevention functional foods

• Basic Process:

  • Alkaline hydrolysis → Solvent extraction → Chromatographic purification → Spray drying

3. Dietary Fiber Supplements

• Contains >50% total dietary fiber, making it ideal for:

  • Fiber-enriched bakery

  • Nutritional cereals

  • Gut-health formulations

4. Animal Feed and Functional Pet Nutrition

• High lignan and fiber content improves:

  • Gut health in ruminants

  • Reproductive and metabolic health in poultry and sows (Cunnane et al., 2004)

Industrial Equipment: Flaxseed Hull Production Line

To support stable and efficient industrial production, a specialized flaxseed hull processing line typically includes:

This configuration allows for automated, low-loss, and food-safe production, compliant with ISO22000 and HACCP standards.

Zhangjiakou Advantage: China’s Emerging Flaxseed Hub

Zhangjiakou, located in Northern Hebei, is a nationally recognized flaxseed-growing zone, characterized by:

• Cold climate and high altitude, which increases oil and lignan content.

• Rich loamy soil — ideal for fiber and gum composition.

• Close proximity to rail and Tianjin port, offering logistics efficiency for global buyers.

Companies in this region leverage Chinese National Standards (GB/T 22492-2008) and industrial norms for flaxseed ingredient extraction, offering traceable, stable, and certified production.

References

• Adolphe, J. L., Whiting, S. J., Juurlink, B. H. J., Thorpe, L. U., & Alcorn, J. (2010). Health effects with consumption of the flax lignan secoisolariciresinol diglucoside. The British Journal of Nutrition, 103(7), 929–938. https://doi.org/10.1017/S0007114509992817

• Cunnane, S. C., Ganguli, S., Menard, C., Liede, A. C., Hamadeh, M. J., Chen, Z.-Y., … & Jenkins, D. J. A. (2004). High alpha-linolenic acid flaxseed (Linum usitatissimum): some nutritional properties in humans. British Journal of Nutrition, 69(2), 443–453.

• GB/T 22492-2008: 《亚麻籽》国家质量标准

• GB/T 5009.8-2022: 粮油类食品蛋白质测定方法

• GB 28050-2011: 预包装食品营养标签通则

Conclusion

Flaxseed hull is no longer just a byproduct—it is a valuable industrial raw material used in the manufacture of high-value ingredients like flaxseed gum, lignan concentrates, and dietary fiber enhancers. With modern processing lines, compliant with Chinese and international standards, producers from Zhangjiakou and surrounding regions are well-positioned to serve the growing demand for clean-label, plant-based functional ingredients.

Whether you’re a functional food formulator, a feed mill, or a nutraceutical company, flaxseed hull offers consistent quality, functional benefits, and proven sourcing advantages from China’s flaxseed capital.