Flaxseed Hull — Technical Product Specification¶
| Field | Details |
|---|---|
| Product Name | Flaxseed Hull (Outer Seed Coat) |
| Product Code | FSP-HUL-001 |
| Revision | V11.0 |
| Issue Date | 2026-07-20 |
| Supersedes | V10.3 (2026-01-15) |
| Prepared By | R&D / Quality Assurance Department |
| Document Owner | Director of Product Development |
| Classification | Public — Technical Datasheet |
1. Product Description¶
Flaxseed Hull is the outer seed coat (testa) of Linum usitatissimum L., mechanically separated from the kernel through a proprietary dry-dehulling process. The hull fraction is enriched in insoluble and soluble dietary fibers, lignans (primarily secoisolariciresinol diglucoside, SDG), and associated polyphenolic compounds. It is intended for use as a functional food ingredient, dietary fiber supplement base, and bioactive compound concentrate for nutraceutical formulations. The product is milled to a controlled particle size distribution and is free from foreign matter, visible mold, and insect infestation.
The dehulling process employs a multi-stage impact dehuller followed by aspiration and sieving trains (three-pass separation) to achieve a minimum 92 % hull purity with less than 8 % residual kernel (endosperm + cotyledon) as determined by microscopic imaging analysis (ISO 13322-2). The final milling step uses a pin mill operating at 3,600 RPM with a 0.8 mm screen aperture.
2. Proximate Composition¶
Analytical parameters determined on an as-is basis. Results are reported as the mean of duplicate analyses.
| Parameter | Specification | Typical Value | Method |
|---|---|---|---|
| Total Dietary Fiber | 70 – 80 % | 74.3 % | AOAC 991.43 |
| Soluble Dietary Fiber | 25 – 35 % | 28.1 % | AOAC 991.43 |
| Insoluble Dietary Fiber | 40 – 48 % | 46.2 % | AOAC 991.43 |
| Protein (N × 6.25) | 10 – 15 % | 12.8 % | AOAC 984.13 |
| Fat (Crude, Acid Hydrolysis) | 8 – 12 % | 10.4 % | AOAC 920.39 |
| Moisture | ≤ 6.0 % | 4.2 % | AOAC 925.10 |
| Ash | 3 – 5 % | 4.1 % | AOAC 923.03 |
| Carbohydrates (by difference) | 3 – 5 % | 4.1 % | Calculation |
Notes: - AOAC 991.43 (Total, Soluble, and Insoluble Dietary Fiber) uses the enzymatic–gravimetric method with phosphate buffer and Termamyl®, protease, and amyloglucosidase digestion. - AOAC 984.13 (Protein) employs the Kjeldahl digestion method with copper catalyst; conversion factor N × 6.25. - AOAC 920.39 (Crude Fat) uses the Soxhlet extraction method with petroleum ether (40–60 °C boiling range), 6-hour extraction cycle. - AOAC 925.10 (Moisture) is determined by forced-air oven drying at 105 °C for 3 hours. - AOAC 923.03 (Ash) by muffle furnace incineration at 550 °C for 6 hours. - Carbohydrates calculated by difference: 100 – (moisture + protein + fat + ash + TDF). Note that TDF is a subset of total carbohydrate so the "by difference" value represents primarily low-molecular-weight sugars and organic acids; typical sucrose content by HPLC (AOAC 2013.12) is < 0.5 %.
3. Nutritional Panel (Per 100 g)¶
Declared values based on compositional analysis. Variations within specification range are expected across production lots.
| Nutrient | Per 100 g | Unit | Method |
|---|---|---|---|
| Energy | 180 – 220 | kcal | Calculation (Atwater factors) |
| Protein | 12 | g | AOAC 984.13 |
| Fat | 10 | g | AOAC 920.39 |
| — Saturated Fat | 1.0 – 1.5 | g | AOAC 996.06 (GC-FID) |
| — Monounsaturated Fat | 2.5 – 3.5 | g | AOAC 996.06 (GC-FID) |
| — Polyunsaturated Fat | 5.5 – 7.0 | g | AOAC 996.06 (GC-FID) |
| — of which α-Linolenic | 4.0 – 5.5 | g | AOAC 996.06 (GC-FID) |
| Carbohydrate | 15 | g | Calculation |
| — Total Dietary Fiber | 75 | g | AOAC 991.43 |
| — of which Soluble | 28 | g | AOAC 991.43 |
| — of which Insoluble | 47 | g | AOAC 991.43 |
| — Sugars | < 0.5 | g | AOAC 982.14 (HPLC-PAD) |
| Sodium | 100 | mg | AOAC 985.35 (ICP-OES) |
Energy calculation: - Protein: 12 g × 4 kcal/g = 48 kcal - Fat: 10 g × 9 kcal/g = 90 kcal - Available carbohydrate (excl. fiber): 15 g – 75 g = negative → adjusted to 0 g; total energy derived from protein and fat only: 138 kcal. The declared range 180–220 kcal accounts for minor metabolizable energy contribution from short-chain fatty acids generated by colonic fermentation, calculated as 1.5–2.0 kcal per gram of soluble fiber × 28 g = 42–56 kcal, yielding a physiological energy total of 180–194 kcal.
4. Mineral Profile¶
Minerals determined by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted nitric acid digestion (EPA Method 3052 modified for food matrices).
| Element | Specification (mg/kg) | Typical (mg/kg) | Method |
|---|---|---|---|
| Calcium (Ca) | 1,800 – 2,200 | 2,010 | AOAC 985.35 |
| Magnesium (Mg) | 350 – 450 | 395 | AOAC 985.35 |
| Potassium (K) | 650 – 850 | 740 | AOAC 985.35 |
| Phosphorus (P) | 500 – 700 | 620 | AOAC 984.27 |
| Sodium (Na) | 80 – 150 | 112 | AOAC 985.35 |
| Iron (Fe) | 25 – 35 | 29.3 | AOAC 985.35 |
| Zinc (Zn) | 4 – 6 | 4.8 | AOAC 985.35 |
| Copper (Cu) | 8 – 12 | 9.6 | AOAC 985.35 |
| Manganese (Mn) | 15 – 25 | 19.2 | AOAC 985.35 |
| Selenium (Se) | 1 – 3 µg/kg | 1.8 µg/kg | AOAC 986.15 |
Notes: - AOAC 985.35 covers Ca, Mg, K, Na, Fe, Zn, Cu, Mn via dry-ashing + ICP-OES. Wavelengths (nm): Ca 317.933, Mg 285.213, K 766.491, Na 589.592, Fe 259.940, Zn 213.856, Cu 324.754, Mn 257.610. - AOAC 984.27 (P) determined by vanadomolybdophosphoric acid colorimetry at 420 nm after dry-ashing. - AOAC 986.15 (Se) uses fluorometric method with 2,3-diaminonaphthalene (DAN) complexation; excitation 340 nm, emission 525 nm. Detection limit 0.1 µg/kg. - Calcium:phosphorus ratio typically 3.2:1, exceeding the > 2:1 threshold desirable for bone health applications.
5. Heavy Metals¶
Determined by inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7900) in collision/reaction cell mode (He flow 4.5 mL/min) after microwave digestion (HNO₃/H₂O₂, 200 °C, 30 min ramp). Method follows AOAC 993.14.
| Heavy Metal | Specification (mg/kg) | Typical (mg/kg) | Method |
|---|---|---|---|
| Arsenic (As) | < 0.5 | 0.12 | AOAC 993.14 |
| Lead (Pb) | < 0.3 | 0.08 | AOAC 993.14 |
| Cadmium (Cd) | < 0.1 | 0.02 | AOAC 993.14 |
| Mercury (Hg) | < 0.02 | < 0.005 | AOAC 993.14 |
Notes: - Quantification limits (LOQ): As = 0.01 mg/kg, Pb = 0.005 mg/kg, Cd = 0.002 mg/kg, Hg = 0.001 mg/kg. - Isotopes monitored: ⁷⁵As (no polyatomic interference correction required in He mode), ²⁰⁸Pb, ¹¹¹Cd, ²⁰²Hg. - All lots comply with EU Regulation 2023/915 maximum levels for foodstuffs and USP <232> limits for dietary ingredients. - Internal standard: ¹⁰³Rh (1 mg/L) introduced via T-piece at 1:1 dilution.
6. Bioactive Compounds¶
Bioactive phytochemicals characteristic of the flaxseed hull fraction. Quantified using validated HPLC-UV / LC-MS/MS methods.
| Compound | Specification | Typical Value | Method |
|---|---|---|---|
| Secoisolariciresinol Diglucoside (SDG) | 7 – 10 mg/g | 8.6 mg/g | HPLC-UV (280 nm) |
| Hydroxycinnamic Acid (HCA) Total | 0.5 – 1.2 mg/g | 0.8 mg/g | HPLC-UV (320 nm) |
| p-Coumaric Acid | 0.3 – 0.6 mg/g | 0.4 mg/g | HPLC-UV (310 nm) |
| Ferulic Acid | 0.2 – 0.5 mg/g | 0.3 mg/g | HPLC-UV (320 nm) |
| Caffeic Acid | 0.05 – 0.15 mg/g | 0.09 mg/g | HPLC-UV (320 nm) |
| Total Polyphenols (GAE) | 12 – 18 mg/g | 15.2 mg/g | Folin–Ciocalteu |
HPLC Conditions for SDG (Method FSP-SDG-003): - Column: Phenomenex Luna C18(2), 250 × 4.6 mm, 5 µm. - Mobile phase A: 0.1 % formic acid in water; Mobile phase B: acetonitrile. - Gradient: 0–5 min 12 % B, 5–30 min 12 → 35 % B, 30–32 min 35 → 60 % B, 32–35 min 60 % B, 35–36 min 60 → 12 % B, 36–42 min 12 % B (re-equilibration). - Flow rate: 1.0 mL/min. Injection volume: 20 µL. Column temperature: 30 °C. - SDG quantified as anhydro-SDG (molecular weight 686.7 g/mol) against external standard (Chromadex, purity ≥ 99 %). Limit of quantitation: 0.02 mg/mL.
Lignan Profile (by LC-MS/MS, Method FSP-LIG-007): - SDG accounts for > 85 % of total lignans. - Minor lignans detected (typical ranges): matairesinol 0.02–0.05 mg/g, lariciresinol 0.01–0.03 mg/g, pinoresinol < 0.01 mg/g.
Antioxidant Capacity:
| Assay | Specification | Typical Value | Method |
|---|---|---|---|
| ORAC (Oxygen Radical Absorbance Capacity) | 150 – 250 µmol TE/g | 198 µmol TE/g | AOAC 2012.23 / Prior et al. (2003) |
| DPPH Radical Scavenging | IC₅₀ 0.8 – 1.5 mg/mL | 1.1 mg/mL | Brand-Williams et al. (1995), modified |
| ABTS•⁺ Cation Radical Scavenging | 80 – 140 µmol TE/g | 112 µmol TE/g | Re et al. (1999), modified |
7. Physical Properties¶
| Property | Specification | Typical Value | Method |
|---|---|---|---|
| Bulk Density (loose) | 0.35 – 0.45 g/mL | 0.39 g/mL | USP <616> Method I, 100 mL graduated cylinder |
| Tapped Density | 0.50 – 0.60 g/mL | 0.54 g/mL | USP <616> Method I, 1250 taps |
| Hausner Ratio | 1.20 – 1.50 | 1.38 | Tapped / Bulk density |
| Carr Index (Compressibility) | 17 – 30 % | 27.8 % | ((Tapped − Bulk) / Tapped) × 100 |
| Particle Size D10 | 100 – 200 µm | 148 µm | Laser diffraction (Malvern Mastersizer 3000) |
| Particle Size D50 | 300 – 600 µm | 412 µm | Laser diffraction (Malvern Mastersizer 3000) |
| Particle Size D90 | 800 – 1,200 µm | 986 µm | Laser diffraction (Malvern Mastersizer 3000) |
| Span ((D90 − D10) / D50) | — | 2.03 | Calculation |
| Water Holding Capacity (WHC) | 6 – 8 g water / g sample | 7.2 g/g | Centrifugation method (20 °C, 1 h hydration) |
| Oil Holding Capacity (OHC) | 2 – 3 g oil / g sample | 2.4 g/g | Centrifugation method (sunflower oil, 20 °C) |
| Swelling Capacity | 12 – 18 mL/g | 15.3 mL/g | Bed volume after 24 h hydration (25 °C) |
| Water Activity (a_w) | < 0.60 | 0.35 | Aqualab 4TE, dew-point sensor (25 °C) |
| Color — CIE L* | 45 – 55 | 49.7 | HunterLab Miniscan XE (D65/10°) |
| Color — CIE a* | 6 – 9 | 7.8 | HunterLab Miniscan XE (D65/10°) |
| Color — CIE b* | 12 – 18 | 15.4 | HunterLab Miniscan XE (D65/10°) |
| pH (10 % w/v slurry) | 5.5 – 6.5 | 6.1 | Potentiometric (AOAC 945.10) |
| Solubility (water, 25 °C) | < 2 % | 0.8 % | Gravimetric, 30 min stirring + centrifugation |
Particle Size Measurement Details: - Instrument: Malvern Mastersizer 3000 with Aero S dry dispersion unit. - Dispersion air pressure: 1.5 bar. Feed rate: 40 %. Refractive index: 1.53 (flaxseed hull), absorption index: 0.01. - Measurement range: 0.01 – 3,500 µm. Obscuration: 0.5 – 5 %. Results averaged over 5 consecutive measurements. - Span calculation: (D90 − D10) / D50.
Hydration Property Methods: - WHC: 1 g sample + 20 mL deionized water, stirred for 5 min, held at 20 °C for 1 h, centrifuged at 3,000 × g for 20 min, supernatant decanted, pellet weighed. WHC = (pellet weight − sample weight) / sample weight. - OHC: 1 g sample + 10 mL sunflower oil (density 0.918 g/mL), vortexed 1 min, held 30 min at 20 °C, centrifuged at 3,000 × g for 20 min, oil decanted, pellet weighed. OHC = (pellet weight − sample weight) / sample weight. - Swelling: 1 g sample in 10 mL water in a graduated cylinder, dispersed, held 24 h at 25 °C. Swelling = (final sediment volume − initial volume) / initial volume (mL/g).
8. Microbiological Specifications¶
Testing performed by ISO 17025 accredited laboratory. Sampling plan per ICMSF, n = 5, c = 2 for indicator organisms; n = 10, c = 0 for pathogens.
| Parameter | Specification | Method |
|---|---|---|
| Standard Plate Count (SPC, 30 °C, 72 h) | ≤ 5,000 CFU/g | ISO 4833-1:2013 (Pour plate, PCA) |
| Yeasts & Molds | ≤ 100 CFU/g | ISO 21527-1:2008 (DRBC agar, 25 °C, 5 days) |
| Coliforms | ≤ 10 CFU/g | ISO 4832:2006 (VRBA, 37 °C, 24 h) |
| Escherichia coli | Negative / 1 g | ISO 16649-2:2001 (TBX agar, 44 °C, 24 h) |
| Salmonella spp. | Negative / 25 g | ISO 6579-1:2017 |
| Listeria monocytogenes | Negative / 25 g | ISO 11290-1:2017 / Amd 1:2019 |
| Bacillus cereus | ≤ 100 CFU/g | ISO 7932:2004 (MYP agar, 30 °C, 24–48 h) |
| Enterobacteriaceae | ≤ 100 CFU/g | ISO 21528-2:2017 (VRBG agar, 37 °C, 24 h) |
| Coagulase-positive Staphylococcus aureus | ≤ 10 CFU/g | ISO 6888-1:2021 (BP agar with RPF, 37 °C, 24–48 h) |
| Sulfite-reducing Clostridia | ≤ 100 CFU/g | ISO 15213:2003 (SC agar, 37 °C, 48 h, anaerobic) |
| Total Enterococci | ≤ 50 CFU/g | ISO 7899-2:2000 (Slanetz–Bartley, 37 °C, 48 h) |
Pathogen Testing: - Salmonella: Pre-enrichment in buffered peptone water (37 °C, 18 h); selective enrichment in RVS broth (42 °C, 24 h) and MKTTn broth (37 °C, 24 h); plating on XLD and BGA agars; biochemical confirmation (API 20E, VITEK 2 GN); serological confirmation (O- and H-antisera). - Listeria monocytogenes: Primary enrichment in Half-Fraser broth (30 °C, 24 h); secondary enrichment in Fraser broth (37 °C, 48 h); plating on PALCAM and OCLA agars; confirmation by β-hemolysis on sheep blood agar (SBA), catalase (+), Gram (+), tumbling motility at 25 °C, and VITEK 2 GP.
9. Packaging Specifications¶
| Packaging Type | Net Weight | Dimensions | Material Description |
|---|---|---|---|
| Standard Bag | 20 kg | 650 × 450 × 120 mm | 3-ply: outer kraft paper (80 g/m²), middle PE film (30 µm), inner food-grade PE liner (80 µm) |
| Bulk Tote (FIBC) | 500 kg | 900 × 900 × 1,200 mm | Type C flexible intermediate bulk container, woven polypropylene with inner PE liner (100 µm) |
| Laboratory Sample Pouch | 500 g | 200 × 300 mm | Triple-sealed foil laminate (Alu/PE/LDPE), nitrogen-flushed |
| Pallet Configuration | 960 kg / pallet | 1,200 × 1,000 × 1,800 mm | 48 bags × 20 kg per pallet, stretch-wrapped, with corner boards |
| Pallet Tie Sheets | — | — | Corrugated cardboard divider between each layer (5 layers, 9–10 bags per layer) |
Packaging Markings: - Product code (FSP-HUL-001), lot number, net weight, manufacture date, expiry date, storage conditions, "KEEP DRY — STORE BELOW 25 °C", "FOOD GRADE — NOT FOR DIRECT CONSUMPTION WITHOUT FORMULATION", FlaxseedsPro logo, barcode (GS1-128). - Kosher certification mark (OU Pareve) and Halal certification logo (IFANCA) on primary label as applicable per lot.
10. Storage Conditions & Shelf Life¶
| Parameter | Requirement / Statement |
|---|---|
| Recommended Storage Temp. | < 25 °C (ambient, climate-controlled) |
| Maximum Short-Term Temp. | 30 °C (not to exceed 72 consecutive hours during transit) |
| Relative Humidity | < 60 % RH |
| Ambient Light | Protect from direct sunlight; store in opaque packaging |
| Shelf Life (sealed, unopened) | 12 months from date of manufacture |
| Shelf Life (opened) | 4 weeks after opening; reseal immediately, store in cool, dry conditions |
| In-Process Hold Time | 72 h maximum between dehulling and final packaging (intermediate bulk) |
| Recommended Storage Area | Dry goods warehouse, separate from aromatic chemicals and spices; HACCP Zone 2 |
Stability Data (Real-Time, 25 °C / 60 % RH, 24 months — study ongoing): - Moisture uptake at 12 months: < 0.5 % increase (sealed package). - TDF retention at 12 months: > 98 % of initial value. - SDG retention at 12 months: > 95 % of initial value (HPLC-UV). - ORAC retention at 12 months: > 92 % of initial value. - SPC count increase at 12 months: < 1 log CFU/g. - No detectable increase in water activity beyond 0.45 a_w. - Free fatty acid (FFA) value at 12 months: < 2.5 % (AOAC 940.28), indicating adequate lipase inactivation from thermal treatment during processing.
Accelerated Stability (40 °C / 75 % RH, 6 months — model): - Predicted shelf life at 25 °C / 60 % RH: 14–16 months (Arrhenius model, Q₁₀ = 2.0 for SDG degradation).
11. Allergen & Regulatory Declarations¶
| Declaration | Statement |
|---|---|
| Gluten Content | < 20 mg/kg (Gluten-free per Codex Alimentarius, ELISA R5 method) |
| Major Allergens (EU 1169/2011) | Contains: None. May contain traces: Mustard, Soy (from shared processing lines). Not produced on lines handling: peanuts, tree nuts, milk, eggs, crustaceans, fish, celery, sesame, lupin, molluscs, sulfites. |
| US FDA Food Allergen Labeling | Not a major allergen under FALCPA 2004 (not among the Big 8). |
| GMO Status | Non-GMO (Identity Preserved). Certified by SGS under EN ISO/IEC 17065. |
| Irradiation | Not irradiated. |
| Organic Status | Available as certified organic variant (Product Code FSP-HUL-001-ORG) |
| Country of Origin | Canada (Saskatchewan and Manitoba) / Kazakhstan (North Region). |
| Kosher | OU Pareve (certificate available on request). |
| Halal | IFANCA Halal certified (certificate available on request). |
| BSE/TSE | BSE/TSE-free (Statement of compliance available on request). |
| Food Contact Materials | Packaging complies with EU 10/2011 and US FDA 21 CFR 175–177. |
12. Quality Control & Compliance¶
- HACCP Plan: FSP-QA-HACCP-07 (Critical control points: raw material receiving, dehulling temperature, metal detection, final sieve analysis).
- GMP Certification: FSSC 22000 (certification body: SGS, certificate no. FSSC-2025-008472).
- Food Safety Testing Frequency: Every production lot for SPC, Y&M, Coliforms, Salmonella, E. coli; quarterly for full pathogen panel; annually for heavy metals and mineral profile verification.
- Traceability: Full lot-level traceability via ERP system (SAP S/4HANA). Raw material lot → production batch → packing date → customer shipment. Full trace-back within 4 hours.
13. Revision History¶
| Revision | Date | Changes |
|---|---|---|
| V1.0 | 2023-03-15 | Initial release. |
| V2.0 | 2023-06-20 | Updated dietary fiber specifications; added ORAC values. |
| V3.0 | 2023-10-10 | Revised heavy metals limits per EU 2023/915. |
| V4.0 | 2024-01-05 | Added particle size distribution and Hausner ratio. |
| V5.0 | 2024-04-18 | Expanded microbiological panel; added B. cereus and C. perfringens. |
| V6.0 | 2024-07-30 | Updated SDG specification range; added HPLC method detail. |
| V7.0 | 2024-10-22 | Revised allergen declaration; added "may contain traces" statements. |
| V8.0 | 2025-02-14 | Added swelling capacity, pH, and solubility physical properties. |
| V9.0 | 2025-06-01 | Updated HACCP plan reference; added FSSC 22000 certification details. |
| V10.0 | 2026-01-15 | Full reformat; added nutritional panel per 100 g; revised mineral specs. |
| V11.0 | 2026-07-20 | Added bioactive compound methods; revised ORAC reference; updated micro methods to ISO standards; added accelerated stability data. Approved by: QA Director. |
— End of Document —
Document ID: FSP-HUL-001-SPEC-V11.0 Total Lines: 376 (including blanks and table rows) Next Review: 2027-01-20