The global shift toward sustainable packaging has placed food-grade kraft board at the forefront of the food service and processing industries. As plastic bans tighten worldwide, businesses are transitioning to paper-based solutions. However, not all kraft paper is created equal. For procurement professionals and brand owners, identifying high-quality, compliant material is not just a matter of aesthetics—it is a critical factor in consumer safety and regulatory compliance.
This guide provides a technical deep dive into the specific metrics that define premium food-grade kraft board, ensuring your packaging preserves food integrity while meeting international safety standards.
Is kraft paper safe for direct food contact?
The short answer is: Only if it is specifically certified as food-grade.
Standard kraft paper is often made from recycled fibers or contains chemical additives that are unsafe for food. In contrast, food-grade kraft board is engineered using virgin wood pulp and processed under strict hygienic conditions. To be safe for direct food contact, the board must meet rigorous migration limits. This means that when the paper touches moist, fatty, or dry food, it must not transfer harmful chemicals, heavy metals, or odors into the food product.
Key safety factors for direct contact include:
- Purity of Raw Materials: Use of 100% virgin fibers sourced from sustainably managed forests.
- Chemical Compliance: Absence of PFAS (per- and polyfluoroalkyl substances) for greaseproofing and no harmful biocides.
- Regulatory Approval: Compliance with standards such as FDA (21 CFR 176.170) in the US or BfR Recommendation XXXVI in Europe.
What is the difference between food grade and regular kraft paper?
Understanding the distinction between these two materials is vital for risk management. While they may look similar to the naked eye, their chemical composition and manufacturing environments are vastly different.
| Feature | Regular Kraft Paper | Food-Grade Kraft Board |
|---|---|---|
| Fiber Source | Often 100% recycled (OCC/Mixed waste) | 100% Virgin wood pulp (typically softwood) |
| Chemical Additives | May contain OBAs, dyes, and industrial glues | FDA-approved sizing agents and wet-strength resins |
| Safety Testing | Minimal or focused on structural strength | Migration testing for heavy metals and MOSH/MOAH |
| Odor/Taint | May carry residual chemical odors | Sensory neutral (No “paper” smell transfer) |
| Surface Finish | Rougher, inconsistent | Controlled smoothness for high-quality printing |
Regular kraft is excellent for shipping boxes and void fill, but using it for food packaging can lead to chemical contamination and brand damage.
Does food-grade kraft board contain fluorescent whitening agents?
One of the most significant indicators of food safety in paper packaging is the absence of Optical Brightening Agents (OBAs) or Fluorescent Whitening Agents (FWAs) .
High-quality food-grade kraft board does not contain fluorescent whitening agents. These chemicals are often used in standard office paper or recycled boards to make them appear whiter and brighter. However, FWAs are known to migrate into food, especially under heat or humidity. In most international jurisdictions, the presence of FWAs in direct-contact packaging is strictly prohibited.
To verify this, professional buyers use a UV light (365nm) . Under UV light, paper containing FWAs will glow bright blue. Pure food-grade kraft board will remain dull or “dead” under the light, indicating it is free from these potentially carcinogenic additives.
What are the key physical metrics for identifying high-quality kraft board?
To ensure the board performs well in a fast-paced food service environment, buyers must evaluate technical specifications. Below are the five essential metrics.
Grammage and Thickness (GSM)
The weight of the paper, measured in Grams per Square Meter (GSM) , directly correlates with its structural integrity.
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Lightweight (40–80 GSM): Used for sandwich wraps and small bags.
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Medium-weight (150–250 GSM): Ideal for meal boxes and takeout trays.
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Heavy-weight (300+ GSM): Required for structural containers and beverage carriers.
High-quality board maintains a consistent thickness across the entire roll (caliper consistency), which is crucial for automated folding and gluing machines.
Cobb Value (Water Absorption)
The Cobb60 value measures the amount of water absorbed by the paper surface in 60 seconds. For food packaging, a low Cobb value is essential to prevent the container from becoming soggy when exposed to moisture or condensation.
- Target: A high-quality liquid-packaging board typically has a Cobb value below 30 g/m².
Tensile and Bursting Strength
Food containers must withstand the weight of the contents and the pressure of stacking.
- Tensile Strength: The maximum stress the board can handle before breaking.
- Bursting Index: Measured in $kPa \cdot m^2/g$, this indicates how much pressure the board can take from the inside out.
Stiffness and Folding Endurance
Stiffness ensures the box keeps its shape during delivery. High-quality kraft board uses long-fiber softwood pulp, which provides superior stiffness compared to short-fiber hardwood or recycled alternatives.
Surface Smoothness and Ink Adhesion
If the packaging requires branding, the surface must be smooth enough for high-definition offset or flexo printing. High-quality board undergoes “calendering” to achieve a uniform surface without sacrificing thickness.
Can food-grade kraft packaging be microwaved?
Modern consumers demand convenience, making “microwaveability” a frequent requirement. Yes, high-quality food-grade kraft board can typically be microwaved, but with several caveats:
- Absence of Metal: The board must not contain any metallic foils or metal-based inks.
- Coating Type: If the board is PE (Polyethylene) coated, it has a lower melting point ($105^\circ C – 110^\circ C$). For high-heat applications, PP (Polypropylene) or PET (Polyethylene Terephthalate) coatings are preferred as they can withstand temperatures up to $120^\circ C$ and $220^\circ C$ respectively.
- Moisture Content: The paper must have a balanced moisture content (typically 6-8%) to prevent it from becoming brittle or scorching in the microwave.
Always look for a “Microwave Safe” certification based on ASTM D6400 or similar thermal stability testing.
How to verify professional certifications?
When sourcing food-grade kraft board, documentation is more important than visual inspection. A reputable supplier should provide a “Declaration of Compliance” (DoC) that includes:
FDA 21 CFR 176.170
This is the “Gold Standard” for the US market, ensuring the paper is safe for use with aqueous and fatty foods.
EU Framework Regulation (EC) No. 1935/2004
This regulation ensures that materials do not transfer their constituents to food in quantities which could endanger human health or bring about an unacceptable change in the composition of the food.
FSC or PEFC Certification
Sustainability is a key component of “quality.” Forest Stewardship Council (FSC) certification proves that the wood pulp was harvested legally and ethically, which is a mandatory requirement for many modern retailers.
Heavy Metal and Phthalate Testing
Testing reports should show that levels of Lead (Pb), Cadmium (Cd), Mercury (Hg), and Hexavalent Chromium (Cr6+) are well within the limits defined by the CONEG (Coalition of Northeastern Governors) or the Packaging and Packaging Waste Directive (94/62/EC) .
What are the common defects in low-quality kraft board?
Avoiding “cheap” alternatives is essential for food safety. Watch out for these red flags:
- Pinholes: Microscopic holes in the coating or fiber mat that lead to grease leakage.
- Delamination: The coating peeling away from the paper base, often caused by poor surface tension during the extrusion process.
- Dusting: Loose fibers on the surface of the paper, which can contaminate the food or clog printing plates.
- Inconsistent Shade: Significant color variations between batches, indicating unstable pulp sources or poor chemical control.
- Odor Taint: A strong chemical or musty smell, which is a sign of recycled content or improper storage.
FAQ
Is all brown kraft paper food safe?
No. Brown color does not guarantee food safety. Many industrial kraft papers are made from recycled waste containing inks and chemicals. Only “Food Grade” certified virgin kraft is safe for direct contact.
How can I test for grease resistance?
Use the Kit Test (TAPPI T 559) . It uses a series of reagents to measure how well the board resists grease penetration, with Level 12 being the highest.
What is the shelf life of food-grade kraft board?
When stored in a cool, dry place away from direct sunlight, the board typically has a shelf life of 12 to 24 months before physical properties may degrade.
Can food-grade kraft be recycled?
Yes, provided it does not have a plastic lining. If it has a PE/PLA coating, it requires specialized recycling facilities to separate the plastic from the fiber.
Why is virgin pulp preferred over recycled pulp?
Virgin pulp ensures the absence of mineral oils (MOSH/MOAH) and provides significantly higher structural strength due to the integrity of the long cellulose fibers.