Perfect Flaky Pastry: Trex vs Butter – Which Fat is Better for Baking?

The first time I made shortcrust pastry entirely with Trex, I wasn't expecting much. I'd grown up watching my grandmother work cold butter into flour with her fingertips—a ritual that seemed almost sacred in her kitchen. But there I was, in my own kitchen on a drizzly November afternoon, about to commit what she'd probably consider pastry heresy. The result? A mince pie base so flaky it practically shattered at first bite. I had questions. Many questions.

If you've ever stood in the baking aisle, Trex in one hand and butter in the other, wondering which will give you that perfect, melt-in-the-mouth pastry, you're not alone. It's a debate that's divided home bakers for decades. And the answer, as I've discovered through many experiments (and a few spectacular failures), isn't as straightforward as you might hope.

What is Trex and Why Do Bakers Swear By It?

Trex is a 100% vegetable baking fat that's been a staple in British kitchens since 1931. It's the UK's answer to American Crisco—a solid white fat that sits somewhere between butter and lard in the baking pantheon.

Here's what makes Trex particularly interesting for pastry-making:

• No water content – Unlike butter (which is about 15-20% water), Trex is pure fat
• Higher melting point – Stays solid at room temperature longer than butter
• Neutral flavour – Won't compete with your filling
• Dairy-free – Suitable for vegan baking and those with dairy allergies

The lack of water is genuinely significant. When butter heats up in the oven, that water content evaporates, which can lead to slightly tougher pastry if you're not careful. Trex sidesteps this entirely.

The Science Behind Flaky Pastry

Before we can properly compare Trex and butter, we need to understand what actually makes pastry flaky. Trust me on this one—a bit of food science goes a long way.

Flaky pastry relies on thin layers of fat distributed throughout the dough. When the pastry hits the oven's heat, the fat melts, creating tiny pockets where steam can expand. The more distinct these fat layers, the flakier your result.

This is where things get interesting:

Butter's advantage: Contains natural milk solids that brown beautifully and add rich, complex flavours. That golden, buttery taste is unmistakable.

Trex's advantage: Being 100% fat with no water means it coats flour particles more completely, creating shorter (more crumbly, melt-in-the-mouth) pastry. In controlled tests, Trex pastries have been shown to be up to 30% flakier than all-butter versions.

My grandmother would have strong words about this. She firmly believed that anything worth baking was worth baking with proper butter. But she also never had to cater for guests with dairy allergies, and she certainly wasn't trying to achieve show-stopping flakiness for Mary Berry-level presentation.

Trex vs Butter: The Direct Comparison

Let me break down exactly how these two fats perform across the factors that actually matter for your baking.

Texture and Flakiness

Winner: Trex

If pure flakiness is your goal, Trex delivers. The absence of water means your pastry won't become tough, even if you handle it a bit too much. It produces a crisper, more shatter-prone texture that's particularly brilliant for mince pies and fruit tarts where you want that dramatic crack when you bite through.

But here's the catch—and this is the honest negative I have to share—all-Trex pastry can be almost too short. It crumbles more readily, which makes it trickier to roll out smoothly. My first few attempts looked more like archaeological ruins than pie bases.

Flavour

Winner: Butter

There's no getting around it: Trex has virtually no flavour. It's purposefully neutral. Butter brings richness, depth, and that unmistakable golden taste that makes you close your eyes in satisfaction.

For sweet tarts where the filling is the star, Trex's neutrality can actually work in your favour. For something like a quiche or a savoury pie where the pastry needs to contribute flavour, butter is the clear choice.

Ease of Handling

Winner: Trex

One of Trex's most practical benefits: you can use it straight from the fridge. With butter, you usually need to let it soften slightly (but not too much—pastry-making is full of these finicky temperature requirements). Trex maintains its workable consistency across a wider temperature range, making it more forgiving for beginners.

Health Considerations

It's complicated

Trex is lower in saturated fat than butter and contains no hydrogenated vegetable oils, which was a concern with older vegetable shortenings. However, butter brings beneficial nutrients like vitamin A and small amounts of vitamin K2.

I know some of you are thinking: "Priya, I'm making pastry, not a health food." And you're right. Neither option is going on any superfood lists. Choose based on what works for your baking, not because you think one is significantly healthier than the other.

Vegan and Dietary Suitability

Winner: Trex

For anyone avoiding dairy—whether for allergies, ethical reasons, or dietary preferences—Trex is the clear choice. It's 100% vegetable-based and suitable for vegans. Combined with a good vegan butter alternative, you can create pastry that rivals traditional recipes.

The Best of Both Worlds: Why 50/50 Works

Here's where I have to share what many experienced bakers have known for years: the best pastry often uses both fats.

A 50/50 combination of Trex and butter gives you:

• The flakiness and crispness of vegetable fat
• The rich flavour of butter
• A more forgiving dough that's easier to roll
• Professional-quality results at home

This is the approach endorsed by traditional recipes for mince pies—half lard (or Trex), half butter. It's also what you'll find in many bakery recipes where consistency matters.

My Go-To Ratio

For 225g total fat (enough for a standard pie or 12 mince pies):

• 112g cold butter, cubed
• 112g Trex, cubed
• 225g plain flour
• Pinch of salt
• 3-4 tablespoons ice-cold water

Rub both fats into the flour until you have fine breadcrumbs. Add water gradually—Trex needs less water than all-butter pastry, so go carefully. Bring together, wrap in cling film, and chill for at least 30 minutes.

When to Choose Trex

Based on my testing—and believe me, there were weeks when my kitchen resembled a pastry factory—here's when Trex is your best option:

Definitely use Trex for:

• Vegan or dairy-free baking
• When maximum flakiness is the priority
• Hot water crust pastry (for pork pies and similar)
• When baking in warm weather (it's more temperature-stable)
• Making large batches where consistency matters

Consider mixing Trex with butter for:

• Mince pies and sweet tarts
• Fruit pies where you want crispness and some flavour
• When you're still developing your pastry skills

When to Choose Butter

Despite my unexpected Trex conversion, butter absolutely has its place:

Stick with butter for:

• Rich shortcrust for savoury tarts and quiches
• Pâte sucrée (sweet pastry) where buttery flavour is essential
• Jus-Rol-style puff pastry alternatives when making from scratch
• When the pastry itself needs to shine (think buttery biscuit bases)

Essential Tips for Working with Trex

If you're new to baking with Trex, these tips will save you from the mistakes I made:

1. Use 20% Less Than Butter

Trex is more concentrated because it contains no water. If a recipe calls for 100g butter, use 80g Trex. This prevents your pastry from being too greasy.

2. Keep Everything Cold

Despite being easier to handle, Trex still benefits from cold temperatures. Cold fat = flaky pastry. This is non-negotiable.

3. Add Water Carefully

Because Trex contains no water, your dough will need less liquid to come together. Add tablespoon by tablespoon, stopping as soon as the dough holds together when pressed.

4. Don't Overwork the Dough

This applies to all pastry, but it's especially important with Trex. Overworking makes it crumbly and difficult to roll. Handle it like you're persuading it, not forcing it.

5. Rest Your Pastry

At least 30 minutes in the fridge. I know it's tempting to skip this step when you're hungry and impatient (I've done it), but rested pastry rolls more easily and shrinks less during baking.

Where to Buy Trex in the UK

Trex is widely available across UK supermarkets. You'll typically find it in the baking aisle near the lard and cooking margarine, or sometimes with the butter alternatives.

Stockists include:

• Tesco
• Sainsbury's
• ASDA
• Morrisons
• Waitrose
• Most local convenience stores

Prices typically range from £1.50-£2.00 for a 250g block—making it comparable to or slightly cheaper than quality butter.

A Note on Flavour Enhancement

If you're using all-Trex pastry and missing that buttery richness, there are workarounds. A few drops of butter flavouring (available from cake decorating suppliers and some supermarkets) can bridge the gap. Alternatively, brush your finished pastry with a little melted butter before the final few minutes of baking—you'll get that golden colour and subtle flavour without compromising the texture.

Actually, this is something my grandmother might have approved of. She was practical above all else, even if she pretended otherwise.

The Verdict

After testing both fats extensively—to the point where my family has requested a temporary moratorium on pies—here's my honest conclusion:

For the flakiest pastry: Trex wins, hands down

For the best-tasting pastry: Butter wins

For the best overall result: Use both

Controversial opinion: if you're only going to keep one fat in your kitchen for pastry-making, I'd actually recommend Trex. Its versatility, ease of use, and dramatic flakiness outweigh the flavour sacrifice—especially when you can always add that butter brush at the end. But I suspect my grandmother is somewhere tutting disapprovingly at this advice, and she wouldn't be entirely wrong.

The beautiful thing about pastry-making is that there's room for experimentation. Try both approaches. Make notes. Adjust. What works brilliantly for mince pies might not be your preference for a weekend quiche. And that's rather the point—cooking is personal, and the best fat for pastry is ultimately the one that makes you happy when you take that first bite.

Frequently Asked Questions

Can you use Trex instead of butter in pastry?

Yes, absolutely. Trex works brilliantly as a butter substitute in pastry. The key adjustment is using 20% less Trex than the recipe's butter quantity because Trex contains no water. You'll also need slightly less water to bring the dough together. The result is typically flakier and crispier than all-butter pastry, though with less buttery flavour.

Is Trex healthier than butter for baking?

Trex is lower in saturated fat than butter and contains no hydrogenated vegetable oils, which were historically a health concern with vegetable shortenings. However, butter provides some nutritional benefits like vitamin A. Neither is a health food—the health difference is marginal when used in typical baking quantities. Choose based on texture, taste, and dietary requirements rather than health claims.

How do you make flaky pastry with Trex?

For flaky pastry with Trex, use a ratio of half fat to flour (so 112g Trex to 225g flour). Cut the cold Trex into small cubes and rub into the flour until it resembles fine breadcrumbs. Add ice-cold water sparingly—just enough to bring the dough together. Wrap in cling film, chill for 30 minutes minimum, then roll on a floured surface. The lack of water in Trex creates exceptionally flaky results when baked at 200-220°C.

What is the best fat for making shortcrust pastry?

The best fat depends on your priorities. For maximum flakiness and crispness, Trex or a 50/50 Trex-butter combination excels. For rich flavour, all-butter shortcrust is superior. Professional bakers often use half butter, half vegetable shortening to achieve both flakiness and taste. For vegan or dairy-free baking, Trex alone delivers excellent results.

Why use Trex for pastry instead of butter?

Bakers choose Trex for several reasons: it produces flakier, crisper pastry due to its 100% fat content with no water; it's more temperature-stable and easier to work with; it's suitable for vegan and dairy-free diets; and you can use it straight from the fridge without waiting for it to soften. Many traditional recipes, particularly for mince pies, have always used vegetable shortening or lard alongside butter for optimal texture.

Where can I buy Trex in UK supermarkets?

Trex is stocked in all major UK supermarkets including Tesco, Sainsbury's, ASDA, Morrisons, and Waitrose. You'll typically find it in the baking aisle near lard and cooking margarine, or sometimes near butter alternatives. A 250g block costs approximately £1.50-£2.00. It's also available online through supermarket delivery services and Amazon UK.

Can you mix Trex and butter together in pastry?

Yes, and many experienced bakers recommend this approach. A 50/50 combination gives you the flakiness of Trex with the flavour of butter—the best of both worlds. This is the traditional method for mince pie pastry and many British pie recipes. Simply cube both fats and rub them into the flour together, using the same total quantity your recipe specifies.