E-numbers / Other additives / E529
also: Quicklime · burnt lime
Quicklime, a naturally occurring mineral compound used in small amounts to regulate acidity and firm texture in certain processed foods.
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Lentil Flour, Rapeseed Oil, Salt, Garlic Purée (3%), Raising Agent (Calcium Oxide), Coconut Oil, Rice Flour, Coriander Leaf, Encapsulated Garlic Oil
Calcium oxide, commonly known as quicklime, is an inorganic mineral compound produced by heating limestone (calcium carbonate) at very high temperatures in a process called calcination.
18
of the 43,325 UK supermarket foods we checked declare E529 in their ingredients
That is under 0.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Calcium oxide, commonly known as quicklime, is an inorganic mineral compound produced by heating limestone (calcium carbonate) at very high temperatures in a process called calcination. It is a white or greyish powder that reacts strongly with water to form calcium hydroxide. In food use it is handled as a dilute processing agent, not in its raw industrial form.
Acts as an acidity regulator by raising pH in food systems, and as a firming agent by cross-linking pectin in plant cell walls. In some applications it also serves as a dough conditioner or mineral carrier. When added to water or wet food matrices it generates calcium hydroxide, which is the active form doing the chemical work. It can also serve as a source of dietary calcium.
Most commonly used in cocoa and chocolate processing (to alkalise cocoa powder, deepening flavour and darkening colour), in maize/corn processing for the traditional technique called nixtamalisation (used to make tortillas and masa products), in some cereal and grain products, and in sugar beet processing. It may appear on a UK label as 'calcium oxide', 'E529', or 'acidity regulator (E529)'.
The calcium delivered by E529 in food is the same mineral that supports bones, teeth, nerve signalling and muscle function. There is no mechanistic reason to treat calcium from calcium oxide differently from calcium in dairy or fortified foods. Regulatory bodies that have reviewed this additive have not identified a toxicological concern specific to its use at permitted levels in food.
EFSA's Panel on Food Additives and Nutrient Sources (ANS) reviewed calcium compounds used as food additives and found no safety concern at the levels of use applied in food processing.
Calcium oxide in its raw industrial form is strongly alkaline and corrosive. At food-grade levels and in processed food matrices, it is present either as dilute calcium hydroxide or as calcium salts formed during processing. The corrosive hazard of raw quicklime is not relevant to the quantities reaching the consumer in finished food. Regulatory limits are designed to ensure the finished food does not carry an unduly high pH.
Calcium oxide is highly reactive with water and corrosive to skin, eyes and mucosa in concentrated industrial form. These properties are neutralised in the dilute food-processing context before the product reaches the consumer.
No specific population group is advised to avoid E529 in food. People on medically supervised low-calcium diets should note that calcium-based additives contribute to total calcium intake, but the amounts involved in food use are generally small. Look for 'calcium oxide' or 'E529' on the ingredients list.
Calcium oxide has been used in food and cooking for centuries, most notably in nixtamalisation of maize, a process documented in Mesoamerican cultures for thousands of years. The additive version is subject to EU and UK quantity limits and EFSA review. There is no live scientific controversy about E529 in food at permitted use levels. The industrial hazard profile of raw quicklime (corrosive, strongly alkaline) is frequently cited online in a way that does not reflect the chemistry of the dilute, reacted form present in finished food products.
No. Calcium oxide (E529) is an approved food additive under the UK FSA's approved-additives list and assimilated EU Regulation 1333/2008, retained in UK law after EU exit.
Yes, calcium oxide is the chemical name for quicklime. In food use it is added in very small, controlled amounts and reacts with moisture to form calcium hydroxide before it reaches the consumer. The corrosive properties of raw industrial quicklime are not present in finished food.
E529 is used in cocoa and chocolate products (where it alkalises cocoa powder), some cereal and flour-based products, maize-based foods such as tortillas made by nixtamalisation, and in sugar beet processing. It reads on UK labels as 'calcium oxide' or 'acidity regulator (E529)'.
Yes. Calcium oxide is derived from limestone (calcium carbonate), a mineral source. It contains no animal-derived ingredients and is suitable for vegans and vegetarians.
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