Preservatives

Sorbic Acid (E200) and Potassium sorbate (E202)

Sorbic Acid (E200) and Potassium sorbate (E202) are used mainly as preservatives as they are effective against a wide range of microorganisms, particularly yeasts and moulds including those responsible for mycotoxin formation. For more information on mycotoxin contamination see here (cross-ref). Sorbic acid and sorbates are often used with other preservatives and can be used in a wide range of foods with a large pH range. They do not interact with other food ingredients and are neutral in taste and flavour. Within the EU sorbic acid and the sorbates are permitted in a range of products with individual maxima in each case. Typical usage levels are 2000ppm in solid food and 300ppm in beverages. Sorbates cannot be used in products where fermentation plays an important role as they inhibit the action of yeast. It is typically used in non-alcoholic beverages, cheese, dairy products, meat products and baked goods.

Benzoic acid (E210), Sodium benzoate (E211), Calcium benzoate (E213) and Potassium benzoate (E212)

Benzoic acid is produced by the oxidation of toluene but also occurs naturally in many plants, may be naturally present due to fermentation and is part of many biochemical processes. The salts of benzoic acid are made by reacting the acid with the appropriate hydroxide and are known as benzoates. Sodium benzoate is the most commonly used of the salts, but its use has been declining since it was in the additive mix with azo dyes used in the Southampton Study (link) which linked these additives to hyperactivity in children.

The benzoates have been used as food preservatives to inhibit the growth of yeasts an moulds since the early 1900’s. They are less effective against bacteria. They are often used in combination with other preservatives such as sorbates and are used with sulphur dioxide which also inhibits enzyme action and browning.

Benzoates are readily soluble in water and widely available, potassium benzoate is used where the sodium content of a product may need to be lowered. They have a distinctive flavour however which limits the concentrations at which they can be used and they cannot be used in yeast-raised flour products as they inactivate yeast. In liquid products which contain ascorbic acid (vitamin C) under certain conditions an interaction can occur which produces benzene (an extremely toxic substance) in levels of a few parts per million.

Benzoic acid and benzoates are permitted in the EU either alone or in combination with other preservatives in a range of products with individual limits in each case. They are most often found in soft drinks. Follow the title link above which is bold and underlined to find out more about the risks to health associated with use of these preservatives.

Parabens: Ethyl p-hydroxybenzoate (E214), Ethyl p-hydroxybenzoate sodium salt (E215), Methyl p-hyroxy benzoate (E218) and Methyl p-hydroxybenzoate sodium salt (E219)

Parabens: Ethyl p-hydroxybenzoate (E214), Ethyl p-hydroxybenzoate sodium salt (E215), Methyl p-hyroxy benzoate (E218) and Methyl p-hydroxybenzoate sodium salt (E219) are esters of p-hydroxybenzoic acid produced by reacting the respective alcohols with p-hydroxybenzoic acid. They are collectively known as parabens and are used as preservatices against yeasts and moulds, but are less effective against bacteria. They are often used in combination with sorbic or benzoic acid, but are rarely used in foods being more commonly used in cosmetic and personal care products. They are very effective antimicrobial agents but their taste makes them detectable even in small amounts in food. They are permitted in the EU in a very limited range of products with individual maxima. There have been a number of health concerns related to parabens and although these are not necessarily food related you can find out about them by following the link in bold and underlined.

Sulphur dioxide (E220), Sodium sulphite (E221), Sodium bisulphite, Sodium hydrogen sulphite (E222), Sodium metabisulphite (E223), Potassium metabisulphite (E224), Calcium sulphite (E226), Calcium bisulphate, calcium hydrogen sulphite (E227) Potassium bisulphate, potassium hydrogen sulphite (E228)

All the substance E220 to E228 are equivalent when they are present in food and E221-E228 are all salts of sulphur dioxide formed when sulphur dioxide is dissolved in water. The actual form of this additive found in food is dependent on the food type and it is only in very acidic foods such as lemon juice or wines that significant amounts of sulphur dioxide occurs. The reason for the number of substances in this group is simply because of how they behave technically in food. E223 and E224 for example are particularly stable on storage or when handled in a factory environment, E226 is however relatively insoluble in water and would be used where solubility needs to be minimised. The most widely used form of this group is E226 – sodium metabisulphite but they are all often just called sulphur dioxide as the recognised method of analysis converts the additive in whatever form it appears into sulphur dioxide and legal specifications therefore refer to the mass of sulphur dioxide released per kg of food.

Sulphites are the most versatile of all additives and have been used in foods since ancient Greece and Rome. They are important ingredients in some traditional foods but they are listed as food preservatives as they primarily act as an antimicrobial agent and to control chemical spoilage. The most well known applications are to prevent browning at the cut or damaged surfaces of plant foods and non-enzymic browning of sugars or vitamin C when foods are processed or stored. Sulphites inhibit most forms of enyzmic spoilage in foods which can otherwise cause off-flavours. They prevent oxidative rancidity when unsaturated fats are oxidised and help to preserve vitamins A and C in foods. E223 is also used as a processing aid to modify the physical characteristics of wheat flour for biscuit manufacture. Sulphites do not restore the colour of discoloured meat but help retain the red colour in sausages.

This group of additives is used widely to preserve fermented and non-fermented beverages spoiling on storage and in wine-making are used to select against wild yeasts in fermentation as well as contributing to the characteristic dry taste in some white wines. Sulphites are used to stop peeled vegetables from browning, to aid storage of dried vegetables, to stop beer staling and have long been used in the production of the pale colour dried fruit such as apricots, peaches an sultanas. They are typically used in soft drinks and fruit juices, fermented drinks including beer, wine and cider, dehydrated vegetables and fruits, peeled potatoes, maraschino cherries, sausages and burgers, jam and biscuits.

Sulphites are a normal part of human metabolism even when there is none in the diet and the human body can metabolise and detoxify this additive when ingested although if the gas is inhaled it can cause an adverse reaction, particularly in those that suffer asthma. They are permitted as additives in the EU but there is some concern that individuals who consume large amounts of wine or have a diet high in foods treated with sulphites  can exceed the ADI for this additive. It is also an anti-nutritive as it destroys vitamin B1 in food. Technically as an additive it reduces in food over time so foods treated have a limited shelf-life. Sulphur dioxide is however the only additive that must be declared in bold on labels as a potential allergen in the EU and you can find out more about potential health risks associated with sulphur dioxide additives following the bold underlined link.

Nisin (E234)

Nisin (E234) is an anti-microbial peptide (small protein) which is produced by certain strains of the lactic acid bacterium Lactococcus lactis subsp. Lactis. Commercial preparations of nisin are prepared by the controlled fermentation of these bacteria in a milk-based medium. Nisin is used as a food preservative as it has strong antimicrobial properties against Gram-positive bacteria but no activity against Gram-negative bacteria, yeasts and moulds. Nisin is an important preservative in pasteurised foods that are not fully sterilised because pasteurisation kills Gram-negative bacteria, yeasts and moulds but not bacterial spores. In heat-processed foods it can be used to allow a reduction in the heat-processing whch improves nutritional content, texture and appearance. It is used in sauces and salad dressings, beer, wine and spirit manufacture and in certain foods such as ricotta, feta and cottage cheese in order to inhibit Listeria monocytogenes. After consumption nisin is degrades in the body by the digestive protease enzymes so it does not accumulate in the body and there have been no reported cases of an allergic response to nisin. Nisin is permitted in the EU in a limited range of foods – clotted cream, certain cheese and cheese products, pasteurised liquid egg, semolina and tapioca puddings – with individual maxima.

Natamycin (E235)

Natamycin (E235) also known as Pimaricin and Tennectin is a natural antimicrobial produced by Streptomycetes bacteria found in soil worldwide. Commercial preparations are made by the controlled fermentation of dextrose media by these bacterial strains. It is used as a food preservative and shows strong activity against yeasts and moulds but no activity against bacteria or viruses. It is mainly used as a fungicidal treatment agent to prevent growth of yeasts and moulds on cheese coatings or sausages. It does not interact with other food ingredients and imparts no flavour and is only permitted in a limited range of products in the EU – surface treatment of hard cheese, cheese products and dried cured sausages.

Hexamethlyeletetramine (E239)

Hexamethlyeletetramine (E239) is made by reacting formaldehyde with ammonia and purifying the product and is used as a preservative which works by releasing formaldehyde in acid conditions. The formaldehyde prevents late blowing in hard cheese by inhibiting the growth of bacteria. It has a slightly sweet taste and a bitter aftertaste and is only permitted in the EU in provolone, an Italian hard cheese to a maximum residual amount of 25mg/kg measured as formaldehyde.

DMDC dimethyl decarbonate (E242)

DMDC dimethyl decarbonate (E242) is manufactured by chemical synthesis and is used as an antimicrobial agent for the cold sterilisation of beverages. Even at very low concentrations is is effective against fermentative yeasts and bacteria and at high concentrations it destroys a large number of bacteria, wild yeasts and moulds. As soon as it is added to beverages it breaks down into minute amounts of methanol and carbon dioxide, but it does not influence the taste, colour or odour of beverages. It is only permitted in the EU in a range of drinks such as fruit based drinks and ready to drink tea.

Ethyl lauroyl arginate (E243)

Ethyl lauroyl arginate (E243) is made by esterifying arginine with ethanol and then reacting with lauroyl chloride and this is used as a preservative in heat-treated meat products. It is particularly useful in inhibiting harmful microorgsanisms such as Listeria monocytogenes. In the EU it is permitted only in heat-treated processed meats and as an allocated ADI of 0-0.5mg/kg of product.

Nitrites: Potassium nitrite (E249) and Sodium nitrite (E250)

 Sodium nitrite is made when a mixture of oxides of nitrogen is passed into sodium hydroxide and the nitrite crystallises on cooling. There is very little production of potassium nitrite for the food industry so sodium nitrite is the dominant product used. This can be found naturally in some plant foods such as lettuce and spinach as well. Nitrites are used to prevent the growth of pathogenic organisms in meat but have no action against yeasts or moulds. The nitrites are one of the few substances available for preserving cured meat by inhibiting the growth of anaerobic bacteria such as Clostridium botulinum and the bacterial effect is enhanced when the nitrite is added before the food is heat processed. Nitrites have the added benefits of preserving the red colour of meat by reacting with myoglobin and in developing a typical ‘cured flavour’ in products. They also act as antioxidants preventing flavour change when cooked meat is exposed to air. In the EU the nitrites are permitted as preservatives only in specificed meat products such as bacon and ham. Nitrites are however associated with potential health risks, particularly an increased risk of colorectal cancer and stomach cancer. While nitrites themselves aren’t directly carcinogenic, they can react with other compounds in the body, especially in the presence of proteins, to form nitrosamines, which are considered carcinogenic. To find out more about the health risks associated with nitrite additives follow the bold and underlined link above.

Nitrates: Sodium Nitrate (E251) and Potassium nitrate (E252).

Sodium nitrate is found in nature as Chile saltpetre and is produced as a by-product in the production of sodium nitrite. Potassium nitrate can also be found in natural products but is produced commercially by reacting potassium carbonate with nitric acid. The major use of nitrates is in agriculture, but nitrates are also naturally present in plant foods including spinach and lettuce and are found in the domestic water supply. The majority of nitrates in the diet arises from these foods and in the EU maximum levels are set for nitrates in food (Regulation 1881/2006) and water (Directive 98/83 EC). Nitrates are therefore both additives and contaminants and you can find out more about nitrates as contaminants here.

Sodium nitrate has been used for at least 2000 years as a preservative often in combination with the nitrite and salt. They work by being converted into nitrite by enzymes in food and in bacteria so the health concerns associated with these additives relate to their conversion to nitrites (E249/E250). Follow the bold underlined link for more information on the health risks of nitrites. Using nitrates is one of the few methods of inhibiting the growth of bacteria such as Clostridium botulinum making them particularly useful in the production of cheese, cured meats and pickled fish. Nitrates are permitted in the EU in a limited range of products – cheese, cheese products, cheese analogues, non-heat-treated processed meats  and traditional cured meat products such as salami.  

Acetic acid (E260)

Acetic acid (E260) is derived from vinegar which is essentially a solution of 5-10% acetic acid in water. Many types of vinegar are available from the oxidation of different sources of alcohol. Acetic acid can also be produced from the oxidation of ethanol industrially.  Acetic acid has been used for thousands of years for the preservation of foods by increasing acidity and inhibiting bacterial growth. It is mostly used where its flavour contributes to the product e.g. in pickles, sauces, marinades and salad dressings. Acetic acid is however more effective against yeasts and moulds than bacteria, with lactobacilli being resistant. Acetic acid has quantum satis status in the EU.

Lactic acid (E270)

Lactic acid (E270) is commercially made from fermentation of sugar or glucose and not from dairy products as may be suggested. Lactic acid has a mild flavour compared with other acids and is used in foods such as yoghurts, processed cheese, pickled vegetables, salads, low-fat mayonnaise, confectionery and some breads. It is effective against both food spoilage and food borne pathogenic bacteria. In combination with acetic acid it inhibits the growth of yeast.  It is used in confectionery to mask the off-flavours from intense sweeteners where these are used. It has quantum satis status in the EU.

Proprionic acid, propanoic acid (E280)

Proprionic acid, propanoic acid (E280) is a naturally occurring acid and is a normal constituent of bodily fluids and is produced from lactic acid using Proprionicbacterium or from oxidising propionaldehyde. It also occurs naturally in ripe Swiss and Jarlsberg cheeses and in the rumen of ruminant mammals. It is used mainly as a mould inhibitor to extend the shelf-life of foods such as bread, cheese and cheese products. High levels of proprionic acid can create bitter, cheesy flavours and reduce the activity of baker’s yeast, which then has to be increased in yeast leavened products. Propionic acid is also used as sodium propionate (E281), calcium propionate (E282) and potassium propionate (E283) as these salts yield the free acid when used in manufacture. They are all considered together in regulatory terms.

The use of propionic acid is controlled in the EU by Regulation 1129/2011 – this only allows its use in a limited number of foods, with individual limits in each case. Propionic acid and the propionates have a joint ADI of 0-6.0mg/kg body weight per day.

EFSA re-reviewed 2014 Re-evaluation of propionic acid – propionates (E 280-283) | EFSA

Boric acid (E284)

Boric acid (E284) is produced from the natural mineral sodium tetraborate (borax) (E285) by reacting borax with sulphuric acid. Borax has been used as a household disinfectant for many years and in the EU it is permitted in food only in caviar to a maximum of 4g/kg.

Sodium lactate (E325) and Potassium lactate (E326)

Sodium lactate (E325) and Potassium lactate (E326) are produced by neutralisation of lactic acid by sodium hydroxide or potassium hydroxide. Their main functions in food are in controlling spoilage and pathogenic bacteria, as a flavouring and in pH regulation where they are used as buffers. Both sodium and potassium lactate can be used in pH-neutral food products such as meat, poultry and fish. Potassium lactate is one of the least bitter potassium salts and can be widely used in the food industry and both lactates are used in confectionery, cooking sauces and other savoury flavours. Lactates control the fermentation of fermented products such as sausages, fermented dairy products and vegetable pickles. Potassium salts are used to reduce sodium contents of finished products. Within the EU they have quantum satis status.

Calcium tartrate (E354)

Calcium tartrate (E354). Calcium tartrate is a salt of tartaric acid, commonly found in grapes and wine. It is used in winemaking to help manage calcium levels and promote tartrate stabilization. It can be used quantum satis in the EU.

Lysozyme (E1105)

Lysozyme (E1105) is an enzyme extracted from hen egg albumen which is used to inhibit the growth of bacteria in hard cheese which cause ‘late blowing’. It can be used in cheese in the place of nitrate and is permitted in the EU quantum satis on ripened cheese and cheese products only.