Bagasse vs PLA vs CPLA: A UK Buyer's Guide to Compostable Materials

Bagasse is sugarcane fibre that handles hot food up to about 100°C, breaks down in industrial or home compost in 60 to 90 days, and is exempt from UK Plastic Packaging Tax. PLA is a clear bioplastic made from corn or sugar that softens above 55°C, only composts industrially, and is still classified as plastic for PPT. CPLA is crystallised PLA pushed to roughly 85°C heat resistance, also industrial-only and PPT-liable. Pick by what the food does to the container, not just by the sustainability badge.

At a glance: the three materials side by side

Bagasse: the fibre, not a plastic

Bagasse is the dry fibrous residue left after sugarcane stalks have been crushed for juice. Moulded into bowls, clamshells, trays and plates, it gives you a strong, rigid container that looks and feels like premium card. Because it is a plant fibre rather than a synthesised polymer, it does two things plastics don't: it tolerates high heat and it composts at lower temperatures.

Lab and field data summarised by Bioleader shows bagasse holding shape for 30 to 40 minutes at 100°C - hot enough for soup, ramen, freshly fried food and oven reheats. Disintegration trials aligned with EN 13432 show more than 90% breakdown of moulded fibre items inside 12 weeks at industrial composting temperatures. In a UK home compost bin, the more realistic 60 to 90 day window from Mana Eco's trial data still holds, subject to moisture and turning.

The other commercial win: bagasse is a fibre, so it is outside the UK Plastic Packaging Tax. HMRC's PPT applies to plastic packaging with less than 30% recycled content, with the 2026 rate set at £228.82 per tonne. Bagasse, paperboard and other non-plastic fibre materials are simply not in scope.

PLA: looks like plastic, taxed like plastic

PLA, or polylactic acid, is a thermoplastic made by fermenting plant sugars from corn, sugarcane or sugar beet into lactic acid and then polymerising it. The result is a clear, glossy material that looks like PET and runs through the same moulds, which is why it dominates cold cup and salad bowl ranges where customers expect to see their drink or food.

The two trade-offs are heat and end-of-life. PLA softens around 55 to 60°C and deforms inside 30 seconds at that temperature. That makes it fine for iced drinks, smoothies, cold-pressed juice, sushi and chilled deli boxes; it is not safe for hot coffee, hot soup, hot takeaway or anything reheated in a microwave.

End-of-life is the bigger compliance trap. PLA needs industrial composting at 58°C and above to break down within the EN 13432 180-day CO2 conversion window. In a UK home compost or wheelie bin it behaves essentially like conventional plastic, which is why UK retailers and councils have pushed back on "home compostable" PLA claims. The ASA's compostable claims guidance requires disposal context, and the April 2025 ASA rulings on coffee pod "compostable" labelling are the live precedent.

And it is still plastic for the tax. Pinsent Masons' PPT guide is explicit: bioplastics including PLA fall inside the Plastic Packaging Tax definition because PPT taxes the polymer, not the source. If your PLA cup contains less than 30% recycled content, you pay the £228.82 per tonne from April 2026.

CPLA: when you need PLA's look with more heat

CPLA stands for crystallised PLA. Manufacturers raise the heat resistance of standard PLA by changing the crystalline structure, typically through nucleating agents and heat treatment. You get a stiffer, more opaque material that holds shape up to about 85°C, summarised in Sontex's CPLA cutlery comparison. That makes CPLA the standard pick for compostable cutlery, hot cup lids and warm meal containers where straight PLA would deform.

The catches are the same as PLA. CPLA is still industrial compostable only, still chargeable under UK PPT, and runs about 20 to 40% more expensive than equivalent PLA. It is also slightly more brittle than PLA, which matters for very thin cutlery and lids: cheap CPLA forks will snap.

The decision matrix: which material for which menu

Tax, certification, and "compostable" language

Three rules to keep your packaging spec and your marketing copy out of trouble:

1. Use the right qualifier. Bagasse certified to EN 13432 can claim "home compostable" if it also passes OK Compost HOME. PLA and CPLA must say "industrial compostable" - never "compostable" alone, never "home compostable". The ASA's guidance is unambiguous and the April 2025 coffee pod rulings show how it is being enforced.
2. Plan for PPT on PLA and CPLA. From 1 April 2026 the rate is £228.82 per tonne. On a typical 16oz PLA cup at around 9 grams, that's roughly 0.2 pence per cup; trivial per unit, painful at 500,000 cups a year for a multi-site cafe brand. Switch to bagasse fibre where heat profile allows.
3. Match material to local infrastructure. If your customers are domestic and your council does not run food/garden waste collection, the practical end-of-life for PLA is still landfill or incineration. Bagasse can at least be home composted; PLA can't.

Common mistakes when speccing compostables

• Putting PLA where hot food touches it. Coffee at 80°C is enough to soften a PLA cup. Use bagasse, aqueous-lined paper or paper plus CPLA lid.
• Mixing PLA cups with bagasse lids. The diameters and rims often don't match; sip-through lids in particular need exact compatibility. Buy as a system.
• Claiming "compostable" without certification. EN 13432 and OK Compost are the recognised standards; "biodegradable" alone is the weakest claim and is the one most likely to get an ASA challenge.
• Forgetting PPT exposure on switched-in bioplastics. A switch from PE-lined paper to PLA may be a net sustainability gain, but PLA still costs you PPT where the PE-lined paper line did not. Run the unit-economic numbers.

Best for: how to pair material to your operation

Frequently asked questions

Is bagasse always home compostable?
Only if it carries OK Compost HOME certification. EN 13432 alone certifies industrial composting. Many UK bagasse lines hold both; ask your supplier for the certificate before you put "home compostable" on your packaging.

Does PLA biodegrade in landfill?
No, not meaningfully. PLA needs sustained temperatures above 58°C with controlled moisture - conditions that exist only in industrial composters, not in landfill or home compost bins.

Is CPLA stronger than PLA?
CPLA is more heat-stable and stiffer at room temperature, but slightly more brittle. For thin cutlery this matters: cheap CPLA forks can snap when stabbing harder food.

Why is PLA still classified as plastic for UK PPT?
The UK Plastic Packaging Tax taxes the polymer, not the source. PLA is a polymer, so it is a plastic for PPT regardless of being plant-based.

What heat can each material take?
Bagasse around 100°C, CPLA around 85°C, PLA around 55-60°C. Everyday rule: hot food / hot drinks need bagasse or CPLA; cold-only is fine for PLA.

How long does each take to break down?
Bagasse: 60-90 days in industrial or home composting. PLA: 90-180 days in industrial composting only. CPLA: similar to PLA, industrial only.

Are these materials cheaper or more expensive than plastic?
Bagasse and PLA cold cups are typically 10-30% more expensive per unit than virgin PP/PET equivalents. CPLA cutlery and lids run 20-40% higher than PP. Factor in PPT (which doesn't apply to bagasse) and the gap narrows quickly.

Can I claim PLA cups are "plant-based" without further qualification?
You can, but pair it with "industrial compostable" so customers and the ASA don't read "plant-based" as "home compostable". The April 2025 ASA rulings show how easily this gets challenged.

The right compostable isn't a single material; it depends on the heat profile, end-of-life infrastructure and PPT exposure for the specific line. We supply bagasse, PLA and CPLA across the UK from stock, with samples available for any line you want to trial. Browse our compostable foodservice range or ask us for a side-by-side sample pack.