Aluminium vs CPET Ready Meal Trays: Which Is Better?
Aluminium and CPET (crystallised PET) are the two most common tray materials for heat-and-eat ready meals. CPET trays are plastic, can go in both a microwave and a conventional oven, and are popular for microwave-led ranges. Aluminium trays conduct heat faster, tolerate much higher oven temperatures, give a better browned or crisp finish and are widely recycled at kerbside across the UK. With extended producer responsibility fees now higher for plastic than for aluminium, many manufacturers are reviewing which material suits each product.
This guide compares the two materials on cooking performance, sealing, food safety, sustainability and cost, to help you choose the right tray for your range.
What is a CPET tray?
CPET is a form of PET plastic that has been crystallised to make it heat resistant. CPET trays are typically rated for use from freezer temperatures up to around 220°C, which makes them dual ovenable: suitable for both microwave and conventional ovens. They are usually black and are widely used for chilled and frozen ready meals.
What is an aluminium ready meal tray?
Aluminium ready meal trays are pressed from aluminium foil, usually in smoothwall form so they have rigid sides and a flat flange for heat sealing. Our smoothwall foil trays are designed for this use, with a reversed rolled edge that gives a firm sealing surface. Aluminium trays are heat resistant to well beyond any domestic or commercial oven temperature and can go from freezer to oven.
Aluminium vs CPET: head-to-head comparison
Oven performance
Aluminium conducts heat very efficiently, so food heats quickly and evenly from the base and sides. This gives a better browned, crisp or caramelised finish, which matters for lasagne, pies, gratins, roasted dishes and baked desserts. CPET heats more slowly in a conventional oven and does not brown the base in the same way. Advantage: aluminium.
Microwave performance
CPET is designed for microwave heating and is the more convenient option for microwave-only products. Aluminium trays can be used in most modern microwaves when they contain food and do not touch the oven walls, but cooking instructions need more care, as our FAQs explain. Advantage: CPET.
Heat sealing and shelf life
Both materials can be heat sealed with lidding film and used with modified atmosphere packaging to extend shelf life. Smoothwall aluminium trays with the right flange seal reliably on standard tray sealers. Our guide to foil container lids explains how film sealing works. Advantage: even.
Food safety
Both materials are safe for food contact when manufactured to UK food contact rules. Aluminium trays can be supplied with an internal lacquer for highly acidic or salty foods, such as tomato-based sauces. Read more in our article on whether aluminium foil is safe for cooking. Advantage: even.
Recyclability
Aluminium is widely collected in UK kerbside recycling and can be recycled repeatedly without losing quality. CPET is harder to recycle in many UK systems, and black plastic trays have historically been difficult for sorting equipment to detect. For brands with recyclability commitments, aluminium is usually the stronger choice. Our article on recyclable foil trays covers this in more detail. Advantage: aluminium.
Regulatory costs
Under UK extended producer responsibility for packaging, producers pay fees per tonne of household packaging, and plastic attracts higher fees than aluminium. PackUK’s illustrative fees for 2026 to 2027 put aluminium at around £245 per tonne for green-rated packaging and £270 for amber, compared with £415 and £455 for plastic. Fees for packaging rated as hard to recycle will also rise each year until 2028 to 2029. Plastic trays may also fall within Plastic Packaging Tax if they contain less than 30% recycled plastic. Advantage: aluminium.
Presentation
CPET trays have a uniform, glossy finish and are available in colours, most commonly black. Smoothwall aluminium trays have a clean, premium metallic finish and can also be coloured on one or both sides. Advantage: depends on brand.
Summary: which tray suits which product?
Choose aluminium if:
- the product is mainly cooked in a conventional oven
- a browned, crisp or baked finish matters, such as lasagne, pies, gratins and crumbles
- recyclability and EPR costs are a priority
- the meal is frozen and goes straight from freezer to oven
Choose CPET if:
- the product is mainly heated in a microwave
- you need one tray that suits both microwave and oven instructions without caveats
Switching from CPET to aluminium
Many ready meal ranges can move from CPET to aluminium with little change to the production line, because both materials are filled, sealed and packed in a similar way. Before switching, check:
- Tray dimensions and flange, so the new tray fits your sealing tools and outer sleeves.
- Fill volume, using a tray with the right capacity for your portion.
- Lidding film, to make sure it seals reliably to aluminium.
- Cooking instructions, retesting oven and microwave guidance with the new tray.
- Lacquer requirements, if the recipe is acidic or salty.
Popular smoothwall formats such as the 220 x 150mm rectangular foil tray, which holds 1,060ml, come in a range of depths, so you can keep one footprint across several portion sizes. Bespoke trays can also be tooled to match an existing CPET footprint.
Frequently asked questions
Which is better for ready meals: aluminium or CPET?
Aluminium is better for oven-cooked meals, browning, recyclability and lower EPR fees. CPET is better for microwave-led products. The right choice depends on how customers will heat the meal.
Are CPET trays recyclable?
CPET is technically recyclable, but it is harder to recycle in many UK systems than aluminium, and black trays can be difficult for sorting equipment to detect.
Can aluminium ready meal trays go in the microwave?
Yes, in most modern microwaves, as long as the tray contains food and does not touch the oven walls. Always follow the microwave manufacturer’s guidance.
Can aluminium trays be heat sealed like CPET?
Yes. Smoothwall aluminium trays with a suitable flange can be heat sealed with lidding film on standard tray sealing machines.
Find the right tray for your ready meal range
Whether you are launching a new range or reviewing an existing one, we can help you compare trays and test them on your line. Explore our support for food manufacturing and food retail, or request samples to trial aluminium trays with your products.
