What Foods Should Not Be Stored in Plastic Containers?

Storing food properly is crucial for maintaining its freshness and safety. While plastic containers are commonly used for food storage due to their convenience, durability, and affordability, not all foods are suitable for storage in plastic. Certain foods can interact with the chemicals in plastic, potentially leading to contamination or a reduction in the food's quality. In this blog post, we’ll explore which foods are best kept out of plastic containers and why, as well as provide tips on alternative storage options.

1. Acidic Foods in PET and PP Containers

Acidic foods such as tomatoes, citrus fruits, vinegar-based dressings, and pickled vegetables can react with the chemicals in some plastic containers. While PET (Polyethylene Terephthalate) containers are commonly used for storing beverages like soda and juices, they may not be ideal for storing highly acidic foods over a long period due to potential chemical leaching. Similarly, PP (Polypropylene) containers, though more resistant to heat and chemicals, may still allow some interaction with highly acidic foods. It’s advisable to use glass or stainless steel containers for long-term storage of acidic foods.

Examples:

• Tomato-based sauces: These are highly acidic and should be stored in glass jars instead of PET or PP containers.
• Lemon juice: Best stored in glass bottles to maintain its flavor and safety.

2. Oily and Fatty Foods in LDPE and HDPE Containers

Oily and fatty foods like butter, cheese, and meat can absorb chemicals from plastic containers, especially when stored for long periods or at high temperatures. Low-Density Polyethylene (LDPE) and High-Density Polyethylene (HDPE) containers are often used for packaging food products because of their durability and resistance to moisture. However, when it comes to storing fatty foods, these plastics may not be the best choice, as fat can facilitate the leaching of chemicals into the food. For oily and fatty foods, glass or ceramic containers are safer options.

Examples:

• Cheese: Store in wax paper or parchment, then wrap in foil for best results, avoiding direct contact with LDPE or HDPE containers.
• Cooked meats: Place in glass containers to preserve freshness and avoid contamination.

3. Hot Foods and the Risks of PVC Containers

Storing hot foods directly in plastic containers can pose a significant risk, particularly with PVC (Polyvinyl Chloride) containers. The heat can cause the plastic to warp or melt, which not only damages the container but also increases the likelihood of harmful chemicals leaching into the food. PVC is known for its chemical stability but can release toxins like dioxins when heated. To avoid this, allow hot foods to cool before transferring them to plastic containers, or use heat-resistant alternatives like glass or ceramic.

Examples:

• Soups and stews: Store in heat-resistant glass containers rather than PVC.
• Leftover casseroles: Allow to cool before placing in storage containers.

4. Strong-Smelling Foods and Odor Retention in PP Containers

Certain foods, such as garlic, onions, and fish, have strong odors that can be absorbed by plastic containers, particularly PP containers. These smells can be difficult to remove and may transfer to other foods stored in the same container later on. Although PP is commonly used for food storage due to its chemical resistance, it is not entirely odor-proof. Using glass containers with airtight lids can help prevent odor absorption.

Examples:

• Garlic cloves: Store in a cool, dry place in a paper bag or ceramic container.
• Fish: Keep in a sealed glass container to prevent odor absorption.

5. Foods Containing Alcohol and the Limitations of PET Containers

Alcoholic foods, such as those prepared with wine, spirits, or extracts, should not be stored in plastic containers, particularly PET containers. Although PET is widely used for beverage bottles, alcohol can act as a solvent, breaking down plastic over time and causing harmful chemicals to leach into the food. For foods containing alcohol, stainless steel or glass containers are recommended for safe storage.

Examples:

• Rum-soaked fruit: Store in glass jars for safe, long-term preservation.
• Alcoholic marinades: Keep in stainless steel or glass containers.

6. Berries and Soft Fruits in HDPE Containers

Berries and other soft fruits can be sensitive to the chemicals found in some plastics. HDPE containers, commonly used for milk jugs and juice bottles, offer good moisture barrier properties but may not be ideal for long-term storage of soft fruits. These fruits may retain moisture, which can cause the plastic to deteriorate more quickly and lead to mold growth. Glass containers or breathable alternatives like ceramic bowls lined with paper towels are better options.

Examples:

• Strawberries: Store in a breathable container like a ceramic bowl lined with paper towels.
• Blueberries: Keep in a glass container with a lid slightly ajar to allow airflow.

7. Fermented Foods and the Importance of Choosing Non-Plastic Containers

Fermented foods like kimchi, sauerkraut, and pickles produce acids and gases during the fermentation process. These substances can interact negatively with plastic containers, particularly those made from LDPE or HDPE, leading to chemical leaching or altering the flavor of the food. Fermented foods are best stored in glass jars with tight-fitting lids to allow for the release of gases without compromising food safety.

Examples:

• Kimchi: Use glass jars with airlock lids to manage gases produced during fermentation.
• Sauerkraut: Store in a glass or ceramic crock for optimal results.

8. Salty Foods in PVC Containers

Foods high in salt, such as cured meats, olives, and soy sauce, can also interact with plastic containers, especially those made from PVC. Salt can cause certain plastics to degrade over time, leading to the leaching of chemicals. Moreover, salty foods stored in plastic may develop an off-taste due to this interaction. Glass or stainless steel containers are ideal for storing salty foods.

Examples:

• Olives: Keep in a glass jar with brine to maintain freshness.
• Cured meats: Wrap in parchment paper and store in the refrigerator.

9. Leftovers Containing Multiple Ingredients in PP and PET Containers

When storing leftovers that contain a mix of ingredients, particularly those that are acidic, fatty, or contain alcohol, it’s important to consider the potential for interaction with plastic. PP and bottle grade PET material containers are commonly used for leftovers, but these complex mixtures can increase the likelihood of chemical leaching, especially when reheated or stored for extended periods. Glass or ceramic containers are better suited for storing such leftovers.

Examples:

• Lasagna: Store in a glass or ceramic dish to keep the layers fresh.
• Salads with vinaigrette: Transfer to a glass bowl with a secure lid for safe storage.

10. Canned Foods After Opening in Non-Plastic Containers

Once canned foods are opened, they should not be stored in their original cans, as the metal may react with the food. However, transferring them to plastic containers, especially those made from PVC or PET, may not be the best option either, especially for acidic or salty foods. Instead, glass or ceramic containers are ideal for storing opened canned goods.

Examples:

• Canned beans: Transfer to a glass container after opening to preserve flavor and safety.
• Canned tomatoes: Store in a glass jar after opening to prevent any metallic taste.

Alternatives to Plastic Containers

While plastic containers have their place in food storage, it's important to recognize their limitations and choose alternative storage options when necessary. Here are some of the best alternatives:

Plastic Container Material Guide: Best and Worst Foods to Store

Understanding the strengths and limitations of different plastic materials can help you make informed decisions about food storage. Here’s a quick guide on which foods are most and least suitable for storage in various types of plastic containers:

PET (Polyethylene Terephthalate)

• Best for: Beverages like water, juice, and soda. PET is excellent for storing non-acidic, non-fatty liquids.
• Worst for: Acidic foods (e.g., tomatoes, citrus juices) and alcoholic beverages. These can cause leaching and alter the flavor and safety of the contents.

PP (Polypropylene)

• Best for: Dry foods like grains, pasta, and cereal. PP is resistant to moisture and chemicals, making it a safe option for these types of foods.
• Worst for: Strong-smelling foods (e.g., garlic, onions) and acidic foods. Odors can linger in PP containers, and acidic foods may cause minor chemical interactions.

LDPE (Low-Density Polyethylene)

• Best for: Frozen foods and lightweight packaging. LDPE is flexible and resistant to moisture, making it ideal for freezing.
• Worst for: Oily and fatty foods (e.g., butter, cheese). These can absorb chemicals from LDPE, especially when exposed to heat.

HDPE (High-Density Polyethylene)

• Best for: Non-acidic liquids and dry foods. HDPE provides a good moisture barrier, making it suitable for items like milk and cereal.
• Worst for: Soft fruits and berries, which may trap moisture and cause the plastic to degrade faster, leading to mold growth.

PVC (Polyvinyl Chloride)

• Best for: Non-food storage or cold storage of non-fatty, non-acidic foods. PVC is sturdy but should be used cautiously for food.
• Worst for: Hot foods and salty foods. Heat can cause PVC to release harmful chemicals, and salt can accelerate degradation.

By selecting the right plastic material for specific food types, you can maximize freshness, safety, and flavor. Always consider the nature of the food and the properties of the container material to ensure optimal storage results.

Understanding which foods should not be stored in plastic containers is crucial for maintaining both the quality of your food and your health. By choosing the appropriate storage methods, such as glass, ceramic, or stainless steel, you can avoid the risks associated with plastic and ensure that your food stays fresh, safe, and delicious. 

About Wankai: Ensuring Quality in Plastic Food Storage Solutions

At Wankai, we understand the critical role that proper food storage plays in maintaining food quality and safety. As a leading supplier and manufacturer of PET resin and PET chips, our expertise extends beyond just producing high-quality materials. We are committed to providing plastic solutions that meet the diverse needs of food storage while ensuring safety and durability.

Our range of PET products is designed to offer optimal performance for a variety of applications, from beverage containers PET to packaging PET. We emphasize the importance of selecting the right plastic material for specific food types, and our products are crafted to adhere to rigorous safety standards to minimize the risk of chemical leaching and ensure food freshness.

In addition to our PET offerings, we are dedicated to educating our clients about the best practices for using plastic containers effectively, aligning with industry standards, and promoting safe food storage practices. For more information about our products and how they can enhance your food storage solutions, visit our website or contact us directly. Wankai PET plastic is committed to supporting your needs with high-quality plastic materials that ensure the safety and freshness of your food.