How to Read a Tortilla Label in the UK: Nixtamal, Wheat Flour and What the Additives Do

A British supermarket sells at least three products under the word tortilla, and they have less in common than the shelf suggests. One is a wheat flatbread. One is maize and wheat blended. One is maize alone, and within that category there is a further split that decides almost everything about how it tastes and whether it will fold without breaking. The packaging rarely makes any of this clear. The ingredient list always does.

This is the companion piece to making corn tortillas at home with UK ingredients. Making your own is the better answer. Reading the label is the answer for the other six days of the week.

Start with the order, because the order is the law

Under UK food labelling rules, ingredients are listed in descending order of weight at the time of manufacture. That one rule does most of the work. If wheat flour appears first and maize second, you are holding a wheat product with maize in it, whatever the front of the pack says about a Mexican recipe. If water appears second, which it often does, that tells you the dough was made wet and the shelf product is relatively moist.

Quantitative ingredient declarations are the second lever. When an ingredient is named or pictured on the front of the pack, the percentage usually has to be declared. So a pack that shouts about maize on the front will often, in small type on the back, admit to containing a specific and sometimes surprisingly modest proportion of it.

The four products, and how to tell them apart in five seconds

What it is	What the list starts with	How it behaves
Wheat tortilla or wrap	Wheat flour, water, vegetable oil or fat	Soft, pliable, long shelf life. A perfectly good flatbread; a bad corn tortilla, because it is not one.
Maize and wheat blend	Wheat flour first, maize flour second, or the reverse	Sold as corn tortillas in many shops. Folds better than pure maize and is not gluten free.
Maize flour tortilla	Maize flour, or cornflour, with water	Made from untreated maize. Breaks and crumbles, tastes mildly of cereal, is where most disappointment comes from.
Nixtamalised maize tortilla	Nixtamalised maize flour, or maize flour treated with calcium hydroxide; sometimes whole maize, water, lime	The real thing. Pliable when warm, strong aroma, distinctly shorter shelf life.

The phrase to hunt for is nixtamalised, or the pair maize and calcium hydroxide appearing in the same list. Calcium hydroxide may also show as E526, or as lime, or as slaked lime. If none of those words is present, the maize was never alkaline-cooked, and the tortilla will neither taste nor behave like a Mexican one. This is not a matter of grade or quality; it is a different process, and the dough's structure depends on it.

One trap worth naming. The word cornflour in Britain means fine white starch for thickening gravy, which is not maize flour and definitely not masa. On an imported pack, corn flour may mean the American milled maize. Judge by the rest of the list and by whether lime appears anywhere.

What the additives are doing there

People assume additives in a tortilla are padding. Mostly they are solving the problem that a product designed to be eaten within two hours of being made is being sold with a date three weeks out.

• Preservatives. Potassium sorbate, calcium propionate, sometimes sorbic acid. Maize dough at ambient temperature grows mould quickly, and these are what stop it. On a fresh tortilla from a tortilleria you will not see them, which is also why that tortilla needs eating or freezing within days.
• Acidity regulators. Fumaric acid, citric acid, sometimes malic. Lowering the pH both inhibits microbial growth and firms the dough. They also, in quantity, add a faint sourness that is a reliable tell of a long-life product.
• Raising agents. Sodium bicarbonate with a phosphate or acid partner, so E450 and E500 often appear together. These belong to wheat tortillas, where a little lift gives the soft, slightly puffed texture people expect from a wrap. In a maize tortilla they are unnecessary.
• Emulsifiers and fats. Mono- and diglycerides of fatty acids, or added vegetable oil. They keep the tortilla flexible and stop it drying on the shelf. Traditional maize tortillas contain no added fat at all, so their presence tells you something about the recipe.
• Gums. Guar and xanthan, which hold water and add elasticity. This is how a gluten-free maize tortilla is made to fold without tearing. In a pack that also lacks any lime, the gums are doing the structural job that nixtamalisation would otherwise have done.
• Calcium hydroxide. The exception on this list. It is not there for shelf life, it is the process itself, and it is the one entry you want to find.

None of this is a reason to avoid industrial tortillas. It is a reason to know which compromise you have bought, because a tortilla propped up with gums and acid wants to be handled differently from one that is just maize and lime.

Why a supermarket corn tortilla cracks when you fold it

Four causes, usually at once. No nixtamalisation, so the dough never developed the structure that lets maize behave like a dough at all. Low moisture, because water is what rots and the manufacturer has removed as much as the product can spare. Cold, because maize starch retrogrades as it cools and a fridge-cold tortilla is physically stiffer than the same one at room temperature. And age, since the staling clock starts the moment it leaves the griddle regardless of the date on the pack.

The fix is heat and steam, and it works on almost any tortilla. Dry pan, medium-high, fifteen to twenty seconds a side until it is flexible and smells toasted, then straight into a lidded bowl or a folded tea towel so the stack steams itself. Microwaving a stack wrapped in a damp cloth for thirty seconds does the same job faster and slightly worse. What does not work is heating them and leaving them open to the air, where they will be stiffer in two minutes than they were cold.

Gluten free is a claim about the law, not about the recipe

A maize tortilla is not automatically gluten free. Blended products contain wheat outright; others are milled or baked in a plant that handles wheat and carry a precautionary statement. If gluten matters medically, the only reliable markers are the explicit gluten-free claim, which is a regulated statement with a legal threshold, or a certification mark. The absence of wheat from the ingredient list is necessary and not sufficient, because cross-contamination is handled through the allergen advice rather than the list.

Conversely, plenty of perfectly good maize tortillas are made in wheat-handling bakeries and carry a may-contain line. For a household without coeliac disease that line is not a quality signal and can be ignored.

Where the genuinely nixtamalised ones come from

A small but growing number of UK producers make tortillas from maize they nixtamalise themselves, supplying restaurants and selling direct, frozen or chilled. Latin American grocers stock both imported and locally made packs, and the better ones will tell you which arrived that week. Some of the mapped shops in our store directory sell fresh masa as well as tortillas, which is the best thing on this page if there is one near you. We have also written about the artisan tortillerias opening across the UK.

Two practical notes on handling the good ones. They freeze perfectly: interleave with greaseproof paper and they separate from frozen. And they will go mouldy in a week in the fridge, because nothing in them is preventing it. That is the trade, and it is the right trade.

The thirty-second shelf test

Turn the pack over. Is the first ingredient maize or wheat? Does the word nixtamalised, lime or calcium hydroxide appear anywhere? How long is the list after the first three items? And what is the date? A short list starting with maize and lime, with a date inside two weeks, is the best industrial tortilla the British retail system currently produces. A long list starting with wheat flour and dated three months out is a wrap, and a wrap makes a decent burrito and a poor taco.

Common questions

Are flour tortillas inauthentic?

No. Wheat flour tortillas are traditional across northern Mexico and a Sonoran flour tortilla is a serious piece of cooking. The problem is a wheat wrap sold as a corn tortilla, not wheat itself.

Why do my tortillas smell faintly sour?

Acidity regulators, or the product is near the end of its life. A fresh nixtamal tortilla smells of toasted maize and nothing else.

Can I refresh tortillas that have gone hard?

Yes, with heat and steam, once. After that they are chilaquiles, which is not a downgrade.