You can properly clean and reuse plastic food trays by first identifying the plastic type, then thoroughly washing them with appropriate methods to ensure safety and longevity. The key is to avoid damage that can lead to chemical leaching or bacterial growth. Many trays, especially those marked with recycling codes #2 (HDPE), #4 (LDPE), and #5 (PP), are sturdy enough for multiple uses if handled correctly. Let’s break down the exact steps and science behind doing this safely.
Understanding Your Plastic: The Resin Identification Code
Before you even think about reusing a tray, flip it over. That small triangle with a number inside is the Resin Identification Code (RIC), and it’s your most important piece of information. Not all plastics are created equal, especially when it comes to heat resistance and structural integrity after initial use. Here’s a quick guide to the most common types you’ll encounter with food trays.
| RIC Code | Plastic Name | Common Uses | Heat Tolerance (°C/°F) | Reuse Safety & Notes |
|---|---|---|---|---|
| #1 (PETE/PET) | Polyethylene Terephthalate | Single-use water/soda bottles | 60-85°C / 140-185°F | Not recommended for reuse. Can harbor bacteria and leach antimony. |
| #2 (HDPE) | High-Density Polyethylene | Milk jugs, yogurt tubs, some sturdy trays | 115-135°C / 239-275°F | Good for reuse. Resistant to chemicals and moisture. Low risk of leaching. |
| #4 (LDPE) | Low-Density Polyethylene | Bread bags, squeezable bottles | 80-95°C / 176-203°F | Generally safe for reuse but less rigid. Check for scratches. |
| #5 (PP) | Polypropylene | Microwaveable meal trays, deli containers, Disposable Takeaway Box | 130-160°C / 266-320°F | Excellent for reuse. High heat resistance. Commonly used for reusable food containers. |
| #6 (PS) | Polystyrene | Foam takeout containers, clear clamshells | 70-95°C / 158-203°F | Avoid reusing. Can leach styrene, especially when heated or with greasy food. |
As you can see, #5 (PP) is your best bet. It’s the workhorse of microwave-safe, reusable plastics. If your tray is #6 (PS) or heavily scratched and cloudy, the safest choice is to recycle it. The structural degradation from scratches creates microscopic havens for bacteria like Salmonella and E. coli, which are difficult to sanitize completely.
The Step-by-Step Cleaning Protocol
Once you’ve confirmed your tray is made from a reusable-friendly plastic like PP or HDPE, follow this detailed cleaning process to ensure it’s hygienic for the next use.
Step 1: Immediate Pre-Rinse
Don’t let food residue dry. As soon as you’re done eating, give the tray a quick rinse with cold water. Cold water is key for protein-based foods (meat, cheese) as hot water can coagulate the proteins, making them stick to the plastic like glue. For greasy foods, a drop of dish soap during this pre-rinse can cut through the oil effectively.
Step 2: Hand Washing vs. Dishwasher
This is a critical decision. While the dishwasher is convenient, it can accelerate the wear and tear on plastic.
- Hand Washing (Recommended): Use a soft sponge or brush and hot, soapy water. Scrub all surfaces, paying special attention to corners and ridges where food particles hide. Abrasive scrubbers or steel wool are a hard no—they create scratches that weaken the plastic and harbor bacteria.
- Dishwasher (Use with Caution): If you must use a dishwasher, place the tray on the top rack, far from the heating element. The high heat at the bottom of the dishwasher can warp or melt plastic trays, even those labeled #5. Use a mild detergent and avoid the heated dry cycle; instead, air dry. Studies show that repeated dishwasher cycles can cause surface degradation, increasing the potential for chemical migration over time.
Step 3: Sanitizing (The Extra Mile)
For absolute peace of mind, especially after holding raw meat or if someone in the household is immunocompromised, a sanitizing step is wise. Create a solution of one tablespoon of unscented household bleach per gallon of cool water. Submerge the tray for about one minute, then rinse thoroughly with clean water. Alternatively, white vinegar can be used, though it is less effective against some pathogens. The CDC recommends bleach solutions for surface sanitization due to their proven efficacy against a broad spectrum of viruses and bacteria.
Step 4: Drying Thoroughly
Moisture is the enemy of stored items. Use a clean, dry dish towel or let the tray air dry completely upside down on a drying rack. Storing a tray while it’s even slightly damp can lead to mildew, which not only ruins the container but can pose health risks.
Inspecting for Damage: When to Retire a Tray
Plastic doesn’t last forever. Regular inspection is non-negotiable for safety. Here’s what to look for:
- Scratches: Run your fingernail across the surface. If it catches in scratches, the tray’s integrity is compromised. Deep scratches are breeding grounds for bacteria.
- Staining and Odors: Plastic is porous. If it’s permanently stained from tomato sauce or holds onto odors from strong foods like curry, it’s a sign that the plastic has degraded and absorbed the material. This can be difficult to clean and may affect the taste and safety of future foods.
- Warping and Cracking: If the tray is bent out of shape or has any visible cracks, it’s time to say goodbye. Warping indicates the plastic polymers have broken down, increasing the likelihood of chemical leaching, especially when heated.
A 2019 review in the Journal of Environmental Science and Health highlighted that physical damage to plastic food containers is a primary factor in the release of microplastics and additives like BPA (though less common in #5 PP) into food.
Creative and Safe Reuse Ideas
A clean, intact tray has a second life beyond the fridge. Here are some practical ways to reuse them while staying within their safety limits.
- Organizers: They’re perfect for sorting small items. Use them in a junk drawer for batteries and screws, in a craft room for buttons and beads, or in the garage for nails and bolts.
- Seed Starters: Poke a few drainage holes in the bottom, fill with potting soil, and you have a perfect mini greenhouse for starting garden seeds. The clear lids of clamshell trays are excellent for this.
- Paint Palettes: For kids’ art projects or small touch-up jobs, a clean tray makes a disposable, easy-to-clean paint palette.
- Drip Trays: Place them under potted plants to catch excess water and protect your furniture.
Important Limitation: Never reuse a plastic food tray for an application that involves high heat, such as an oven tray or a direct stovetop surface. Even #5 PP has its limits, and repurposing it for high-heat cooking is a fire hazard and will certainly cause chemical leaching.
The Environmental and Health Perspective
Reusing a plastic tray a few times before recycling it is undeniably better than a single-use mindset. It reduces immediate waste. However, it’s a temporary solution. The production of these trays still consumes resources, and all plastics will eventually degrade to a point where they must be discarded. The most sustainable practice is to transition to durable, long-term solutions like glass or stainless-steel containers for food storage. These materials are non-porous, don’t scratch easily, and can be safely heated without risk of chemical migration, making them a healthier and more eco-friendly choice over their entire lifespan. Reusing plastic trays should be viewed as a way to extend their life responsibly while you make that transition, not as a permanent system.