With plastic pollution becoming a global crisis, more people are turning to eco-friendly alternatives. One option gaining attention is the biodegradable corn starch bag — a sustainable replacement for traditional plastic bags.
But what exactly are these bags? And can they truly help reduce environmental harm?
In this article, we explain what corn starch bags are made of, how they work, and why businesses are choosing them over plastic.
What Are Corn Starch Biodegradable Bags?
Corn Starch Biodegradable Bags are eco-friendly bags made primarily from corn starch, a renewable resource, and processed into polylactic acid (PLA), a biodegradable polymer.
What Are Corn Starch Bags Made Of? What is the source of the material?
Biodegradable corn starch bags are typically made from:
- Corn starch – A renewable material derived from corn plants
- PBAT – A biodegradable polymer that improves flexibility
- PLA (optional) – A plant-based bioplastic made from fermented corn
This blend allows the bags to function like plastic, while being non-toxic and compostable.
Corn Starch Biodegradable Bags Vs Traditional Plastic Bags
| Feature | Biodegradable Corn Starch Bags | Traditional Plastic Bags |
|---|---|---|
| Decomposition Time | 90–180 days (in industrial composting) | 100–1000 years |
| Environmental Impact | No microplastics, fully compostable | Generates microplastics, pollutes soil and water |
| Raw Material | Renewable corn starch | Petroleum-based plastic |
What is Corn Starch Bags Manufacturing Process?
Corn Harvesting and Starch Extraction:
Raw Material: The process begins with corn (maize), a renewable crop rich in starch.
Starch Extraction: Corn kernels are milled to separate the starch from other components (like protein and fiber). This is typically done through a wet milling process:
Corn is soaked in water with sulfur dioxide to soften the kernels.
The mixture is ground to release starch, which is then separated, washed, and dried into a fine powder.
Conversion to Lactic Acid:
Fermentation: The corn starch is mixed with water and enzymes to break it down into simple sugars (glucose). These sugars are then fermented using bacteria (such as Lactobacillus) in a controlled environment.
Output: The fermentation process produces lactic acid, the building block for PLA.
Polymerization to Polylactic Acid (PLA):
Condensation: Lactic acid molecules are chemically processed to form lactide, a cyclic compound.
Polymerization: Lactide is heated and catalyzed to create long chains of polylactic acid (PLA), a biodegradable thermoplastic. This step requires precise temperature and pressure control to ensure the PLA has the desired strength and flexibility.
Pelletization: The PLA is cooled and extruded into small pellets, which are easier to handle for further processing.
Blending with Additives (Optional):
To enhance properties like flexibility, durability, or transparency, PLA may be blended with other biodegradable materials (e.g., polybutylene adipate terephthalate, PBAT) or natural additives.
Additives are carefully chosen to maintain the bag’s compostability and compliance with standards like ASTM D6400 or EN13432.
Film Extrusion:
Melting and Extrusion: PLA pellets are melted in an extruder and forced through a die to form a thin, continuous film. This film can be adjusted for thickness (typically 0.02–0.05 mm for bags).
Blowing or Casting: The film is either blown into a tube (for blown film extrusion) or cast flat (for cast film extrusion), depending on the bag type. Blown film is common for shopping or garbage bags due to its strength.
Bag Forming and Cutting:
Printing (Optional): The PLA film may be printed with eco-friendly inks for branding or labeling (e.g., logos or compostable certifications).
Cutting and Sealing: The film is cut into the desired bag shape and heat-sealed to form the bottom and sides. Handles or drawstrings may be added for specific designs.
Quality Control: Bags are inspected for strength, thickness, and defects to ensure they meet standards.
Packaging and Distribution:
The finished bags are rolled, folded, or stacked, then packaged for distribution to retailers, wholesalers, or businesses.
Manufacturers often include labels indicating the bags’ biodegradable properties and proper disposal instructions (e.g., “Compostable in industrial facilities”).
Are Corn Starch Bags Really Biodegradable?
Yes — when properly certified.
Corn starch bags break down naturally in composting environments, turning into water, carbon dioxide, and organic matter. Depending on the composting conditions, they can degrade in 3 to 6 months.
Look for these certifications to confirm biodegradability:
- EN13432 – European standard for compostability
- ASTM D6400 – US standard for compostable plastics
- OK Compost HOME – Suitable for home compost bins
- BPI Certified – Trusted North American compost label
Benefits of Biodegradable Corn Starch Bags
- Compliant with green regulations
Ideal for businesses aiming to reduce their carbon footprint. - Reduces landfill waste
These bags won’t stay in the environment for hundreds of years like plastic. - Made from renewable materials
No fossil fuels, no microplastics. - Safe for food and compost
Suitable for kitchen use, pet waste, and food packaging.
How to Choose and Buy Corn Starch Bags
If you have decided to try corn starch biodegradable bags, here are some shopping tips to help you find high-quality products:
- Check certification: Give priority to bags certified by ASTM D6400 or EN13432 to ensure that they are truly biodegradable.
- Consider the purpose: Choose the appropriate thickness (0.02-0.05mm) and size according to the needs. For example, garbage bags need to be thicker, while shopping bags focus on lightness.
- Check reviews: When buying on e-commerce platforms (such as Taobao and JD.com), read user reviews to understand the durability and actual effect of the bags.
- Wholesale discounts: If it is a bulk purchase (such as corporate use), contact the supplier directly to negotiate, the minimum order quantity is usually 10,000, the price is lower, and it can be customized.
CTA: Want to get started right away? Contact us for recommended suppliers.
Challenges of Corn Starch Biodegradable Bags
- Higher cost: Due to the production process and raw material costs, the unit price of corn starch bags (about 0.5-2 yuan) is generally higher than that of traditional plastic bags (about 0.1-0.5 yuan). However, as the scale of production expands, the price gap is narrowing, and wholesale purchases are more cost-effective.
- Composting requirements: These bags decompose fastest in industrial composting facilities (where temperature, humidity and microbial conditions are ideal). Home composting may take longer, and the effect varies depending on the environment.
- Recycling limitations: Corn starch bags are not suitable for traditional plastic recycling systems and need to be sent to specialized composting facilities. If there is a lack of relevant facilities in the local area, disposal may become a problem.
- Misconception: Some “degradable” bags on the market are not truly biodegradable, and consumers need to pay attention to certification marks (such as ASTM D6400) to ensure that they are purchasing authentic products.
Despite these limitations, the overall environmental benefits of corn starch bags are still significant. Choosing reliable suppliers and using them correctly can maximize their value.
Conclusion
Corn starch bags are more than a trend — they’re a sustainable solution to a real problem. Businesses around the world are switching to biodegradable packaging, not just to protect the planet, but to meet rising customer demand.
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