A Guide to Permitted Food Additives and Preservatives

Every time you pick up a bottle of fruit juice, a packet of dried apricots, or a loaf of bread, there’s a good chance that a carefully regulated preservative is quietly at work inside. These substances – known as permitted food additives – are not random chemicals thrown into food to cut costs or deceive consumers. They have defined identities, legal limits, and legitimate technological purposes. Understanding how they are classified and why they are used is essential knowledge for anyone working with food processing and post-harvest management.

What is a food additive? 🔗

A food additive is any substance not normally consumed as food by itself, whose intentional addition serves a technological purpose during the manufacture, processing, preparation, treatment, packing, transport, or storage of food. This definition, adopted by both the Codex Alimentarius Commission (FAO/WHO) and India’s own Food Safety and Standards Authority of India (FSSAI), explicitly excludes contaminants and substances added purely to improve nutritional quality. In short, a preservative added to prevent mould growth qualifies; a vitamin added for fortification does not fall under the same umbrella.

Among all categories of food additives, preservatives hold special importance in post-harvest management. From prehistoric times, humans have attempted to protect food from the deteriorative effects of microorganisms. Chemical food preservatives like salt, nitrites, and sulphites have been in use for centuries. Even though newer packaging techniques and cold-chain systems can preserve food without chemical additives, preservation using approved chemicals remains cheaper and more practically viable – especially in warm and humid climates where spoilage accelerates quickly.

Classification of preservatives: Class I and Class II 🔗

Under India’s Prevention of Food Adulteration (PFA) Act, 1954 – now subsumed under the broader FSSAI regulatory framework – preservatives are classified into two broad classes: Class I (natural preservatives) and Class II (synthetic chemical preservatives). This two-tier system reflects both the origin of the substances and the degree of regulatory caution applied to each.

Class I preservatives: nature’s own tools 🔗

Class I preservatives are natural substances that have been used in kitchens and food processing for thousands of years. They include common salt (sodium chloride), sugar, dextrose, glucose syrup, honey, and vegetable oils. There is no restriction on the addition of Class I preservatives to any food. This is because, at the concentrations used in normal food preparation, these substances pose no appreciable health risk.

Each of these works through well-understood physical or chemical mechanisms. Salt and sugar, for instance, reduce the water activity (a_w) of food – meaning they bind free water and make it unavailable to microbial cells. Bacteria and fungi require free water to grow; when it is withdrawn, they cannot multiply. Vinegar (acetic acid) lowers the pH of food, creating an acidic environment that is hostile to most spoilage microorganisms. Acetic acid in the form of vinegar is generally used for the preservation of vegetables as pickles, and its antimicrobial activity increases at low pH. Wood smoke, another Class I preservative, works differently – it deposits phenolic compounds and formaldehyde onto food surfaces, inhibiting microbial growth while also imparting flavour.

Class II preservatives: synthetic and strictly regulated 🔗

Class II preservatives are man-made chemical compounds that offer more potent and targeted antimicrobial activity. They include benzoic acid and its salts, sulphurous acid and its salts, nitrates and nitrites, sorbic acid and its sodium, potassium, and calcium salts, calcium and sodium propionates, lactic acid, methyl or propyl parahydroxybenzoic acid (parabens), sodium diacetate, and sodium, potassium, and calcium lactate. Unlike Class I preservatives, Class II substances are subject to strict maximum permissible limits, and their use is restricted to specific food categories.

The regulatory principle governing their use is clear: the use of food additives is justified only when such use has an advantage, does not present an appreciable health risk to consumers, does not mislead the consumer, and serves one or more of the technological functions specified by bodies like Codex. Each Class II preservative must be used at the lowest level necessary to achieve the intended effect – a principle known as Good Manufacturing Practice (GMP).

Key Class II preservatives and how they work 🔗

Benzoic acid and its salts 🔗

Benzoic acid is among the oldest and most widely used preservatives, and it occurs naturally in cranberries and certain berries. Its low toxicity and absence of colour make it particularly desirable. It works best in acidic conditions – most effectively at pH below 4.5. Benzoic acid and its salts are most suitable for foods and beverages that are naturally acidic or that can be acidified, and have therefore been widely used to preserve beverages, fruit products, bakery products, fish products, margarine, mayonnaise, and sauces.

Because benzoic acid has limited solubility in water, it is most commonly used in the form of sodium benzoate, which dissolves easily. The maximum permissible concentration of benzoic acid and benzoates in most foods is 0.1%. Its mechanism of action involves penetration of the undissociated acid form through the microbial cell membrane, followed by intracellular dissociation that disrupts metabolism – effectively stopping yeast and mould growth.

Sulphur dioxide and sulphites 🔗

Sulphur dioxide (SO₂) and related sulphite salts are among the most versatile Class II preservatives. Sulphur dioxide is used to preserve colour and increase the shelf life of dried foods; sulphuring is the more common technique for fruits, while sulphiting is typically used for vegetables.

In aqueous solution, sulphur dioxide and sulphites form sulphurous acid and bisulphite ions, which prevent the growth of yeasts and moulds. The antimicrobial activity is attributed to the reaction of bisulphite with acetaldehyde in microbial cells, the reduction of enzyme disulphide linkages, and interference with cellular respiration. Sulphites are also used in wines as both an antioxidant and an antiseptic agent.

However, sulphur dioxide comes with important restrictions. Sulphur dioxide and sulphites cannot be used in meats or in foods that are sources of the vitamin thiamine, as sulphites destroy this nutrient. They also have a strong bleaching action on plant pigments like anthocyanins and have been found to trigger allergic responses in certain individuals, particularly asthmatics.

Sorbic acid and sorbates 🔗

Sorbic acid and its salts – especially potassium sorbate and calcium sorbate – are antimicrobial agents used to prevent the growth of mould, yeast, and fungi in a wide range of food and beverage products. Sorbic acid was first isolated in 1859 from the berries of the rowan tree (Sorbus aucuparia), and its natural origin contributes to its broader acceptance. Sorbic acid and sorbate salts have very low mammalian toxicity and carcinogenicity, making them among the safest synthetic preservatives available.

Sorbic acid and its potassium salt are among the most efficient and versatile food preservatives in use today. They are effective inhibitors of most common spoilage microorganisms without adversely affecting the taste, colour, or flavour of the food. They are most effective below pH 6.0 and are used in cheese, baked goods, fruit juices, salad dressings, wines, and carbonated beverages.

Nitrates and nitrites 🔗

Sodium and potassium nitrite and nitrate are primarily used in cured and processed meat products. Their role extends beyond preservation – nitrite is used as both a preservative and a colour fixative in smoked and cured meat and fish products, where the level of sodium nitrite is regulated not to exceed 200 parts per million in the finished product. Nitrites are particularly effective in inhibiting Clostridium botulinum, the organism responsible for botulism, which is a significant concern in anaerobic, low-acid food environments.

Calcium and sodium propionate 🔗

Calcium propionate is an organic salt widely applied in bread and commercial baked goods to prevent and reduce mould growth. It is also present in dairy items, alcoholic beverages, and processed meats. The sodium and calcium salts of propionic acid have antimicrobial activity against moulds and some bacteria. The inability of microbes to metabolize its three-carbon structure is what gives it toxic effects on microbial cells.

The legitimate uses of food additives in processing 🔗

It is important to understand that permitted food additives are not used arbitrarily. The Codex Alimentarius Commission established that food additives are justified only when they serve specific purposes – and these purposes are tightly defined. According to the Codex General Standard for Food Additives (CXS 192-1995), the four legitimate technological justifications for using food additives are:

1. Preserving nutritional quality 🔗

Certain additives are used specifically to prevent the degradation of vitamins, minerals, and other nutrients during storage and processing. Antioxidants such as ascorbic acid (vitamin C) and tocopherols (vitamin E) slow the oxidation of fats, which would otherwise destroy fat-soluble vitamins and generate off-flavours. Sulphur dioxide, while restrictive in some applications, helps retain vitamin C in fruit products that would otherwise lose it quickly after processing.

2. Providing ingredients for special dietary needs 🔗

Additives may be justified to provide necessary ingredients or constituents for foods manufactured for groups of consumers with special dietary needs – such as diabetics, infants, or patients with specific medical conditions. Non-caloric sweeteners, for instance, allow people with diabetes to consume palatable foods without glucose spikes.

3. Enhancing stability and keeping quality 🔗

This is the primary justification for most preservatives. The use of food additives is justified when it enhances keeping quality or stability with a resulting reduction in food wastage. In countries with warm climates and extended supply chains, chemical preservation is often the most practical method of ensuring that food reaches the consumer in a safe condition. Extending the shelf life of products like fruit pulp, bread, or squashes directly reduces post-harvest losses.

4. Providing processing aids 🔗

Food additives are also justified as aids in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food – provided that they are not used to disguise faulty raw materials or poor hygiene practices. Emulsifiers that allow oil and water to blend uniformly, acidulants that control pH during fermentation, and anti-foaming agents used in juice clarification all fall into this category of processing aids with legitimate technological roles.

Labelling and consumer transparency 🔗

Transparency is a cornerstone of food additive regulation. In India, FSSAI, created under the Food Safety and Standards Act 2006, handles the drafting of rules, creating safety standards, and monitoring food entering or leaving the country. Under FSSAI labelling requirements, food additives must be declared on the product label using their functional class name (such as “preservative”) followed by either the specific name of the additive or its International Numbering System (INS) code. For example, sodium benzoate would appear as “Preservative (INS 211)” on an Indian food label. This system allows consumers to make informed choices without needing to know the chemistry behind each compound.

When two or more additives of the same functional class are used together – for instance, a combination of benzoic acid and sorbic acid in a fruit beverage – the sum of their respective ratios to the maximum permitted level should not exceed 1. This additive effect principle ensures that combined use does not push total exposure beyond safe limits.

Safety evaluation and the ADI concept 🔗

Before any Class II preservative receives regulatory approval, it undergoes a rigorous safety evaluation. The Codex Alimentarius Commission relies on assessments by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), which establishes an Acceptable Daily Intake (ADI) for each substance. The ADI represents the estimated amount that can be ingested daily over a lifetime without appreciable health risk. Maximum permitted use levels in individual food products are then set so that even a person consuming large amounts of the relevant foods would not exceed this daily intake. This science-based, multi-layered system is what distinguishes a permitted food additive from an adulterated or unsafe ingredient.

What do you think? Given that Class I preservatives like salt and sugar have no usage restrictions while Class II preservatives are tightly regulated by law, does the current classification system adequately reflect modern food safety science? And as post-harvest losses remain a significant challenge in warm-climate countries like India, do you think the role of permitted chemical preservatives in reducing food waste deserves more recognition in public discourse?

References

1. https://www.fao.org/fao-who-codexalimentarius/codex-texts/dbs/gsfa/en/
2. https://www.fssai.gov.in/upload/uploadfiles/files/Compendium_Food_Additives_Regulations_20_12_2022.pdf
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12. https://thewholetruthfoods.com/learn/twt-chemx/e282-or-calcium-propionate
13. https://www.fao.org/4/66479e/66479E18.htm
14. https://www.fao.org/gsfaonline/docs/CXS_192e.pdf
15. https://www.fao.org/4/a3025e/A3025E26.htm
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17. https://www.fsis.usda.gov/sites/default/files/media_file/2021-02/Gb-2760-2015-part1.pdf