Review

Salt (food ingredient)

Description
Food-grade salt is composed mainly of sodium chloride (NaCl), an essential mineral for human physiology and one of the most widely used ingredients worldwide. It can come from evaporation of seawater (sea salt), crystallisation of brines, or mining of underground deposits (rock salt/halite), followed by purification. It appears as white crystals, regular or irregular, with variable particle size (fine, medium, coarse). Salt is used to provide savouriness, preserve foods, influence texture, support fermentations and enable numerous technological processes. On land, salt is extracted from mines in the form of rock salt and then processed.

Sea salt is salt obtained from seawater, collected in tanks and evaporated in the sun.

Then there is iodized salt, which is a common sea salt to which iodine or potassium, elements that the human body needs, have been added.

There is also diet salt, with a lower percentage of sodium and then a large amount of salt from the most diverse parts of the gobo, Himalayan pink salt, South Africa, China etc.

Indicative nutritional values per 100 g

• Energy: 0 kcal

• Water: 0–2 g (residual moisture)

• Carbohydrates: 0 g

• Protein: 0 g

• Total fat: 0 g

  • SFA: 0 g

  • MUFA: 0 g

  • PUFA: 0 g

• Fibre: 0 g

• Sodium: 38–40 g

• Chloride: ≈ 60 g

• Trace minerals (calcium, magnesium, potassium), especially in less-refined sea salt

Key constituents

• Sodium chloride (NaCl) → main component (typically 97–99%).

• Traces of chlorides and sulphates of magnesium, calcium and potassium (more evident in unrefined sea salt).

• Authorised anti-caking agents in packaged table salt.

• Iodine (in iodised salt), usually as potassium iodide or iodate according to legislation.

Production process

Sea salt

• Collection of seawater in saltpans.

• Natural evaporation by sun and wind.

• Crystallisation of NaCl.

• Harvesting, washing and drying of crystals.

• Particle-size grading and, if required, iodisation.

• Packaging for food use.

Rock salt (halite)

• Extraction from underground deposits (mining or solution mining + recrystallisation).

• Crushing, purification and grading.

• Iodisation where required by law or market.

• Packaging for food use (clearly distinguished from technical salt).

Physical properties

• White, odourless crystals, fully soluble in water.

• Variable bulk density depending on particle size.

• High melting point (around 801 °C; relevant mainly for technical uses).

• Hygroscopic: tends to absorb moisture and form lumps.

• Crystal habit: cubic in pure NaCl; grains may appear irregular after crushing.

Sensory and technological properties

• Taste: intensely salty, clean, without off-flavours in quality products.

• Enhances flavours and sweetness, and can mask or reduce bitterness.

• Key technological roles:

  • Osmosis (brines, partial dehydration, osmotic balance in fermentation).

  • Fermentation support (bread dough, vegetable fermentations).

  • Preservation (reduces water activity and inhibits microbial growth).

  • Texture modulation (meat products, cheeses, baked goods).

Food applications

• Direct seasoning in home and professional cooking.

• Preparation of brines for cheeses, olives, pickled vegetables and cured meats.

• Curing of meats and fish (e.g. hams, bacon, cod).

• Bread and bakery products, snacks, processed meats, cheeses and canned foods.

• Salt-crust baking of fish and meat.

• Numerous industrial applications in preservation and processing.

Nutrition & health

• Salt is the main dietary source of sodium, essential for:

  • Fluid and electrolyte balance.

  • Nerve transmission.

  • Muscle contraction.

• However, excessive intake is associated with:

  • Hypertension.

  • Increased cardiovascular risk.

  • Possible kidney overload in susceptible individuals.

• Health guidelines typically recommend less than 5 g of salt per day for adults (all sources combined).

• Iodised salt contributes to iodine intake, important for thyroid function, especially in areas with low natural iodine.

Portion note
The recommended daily intake is below 5 g of salt per adult, including both added salt and salt contained in processed foods.

Allergens and intolerances

• Salt does not contain EU-listed major allergens.

• It may need to be reduced or restricted in individuals with:

  • Hypertension.

  • Kidney disease.

  • Heart failure or certain endocrine disorders.

• Sensitivity to iodine in iodised salt may be relevant for specific medical conditions (follow medical advice).

Storage and shelf-life

• Store in a cool, dry place, away from humidity and strong odours.

• Keep the container tightly closed to prevent clumping and odour absorption.

• Salt has a very long shelf-life (often several years); for iodised salt, the limiting factor is mainly iodine stability, not spoilage of the salt itself.

Safety and regulatory aspects

• Must comply with EU and national requirements for:

  • NaCl purity.

  • Heavy metals and insoluble impurities.

  • Permitted additives.

  • Iodisation levels (for iodised salt).

• Production must follow GMP and HACCP systems.

• Food-grade salt must be clearly separated from technical/industrial salt along the supply chain.

Labelling

• Sales name: edible salt, sea salt, rock salt, etc., depending on origin and processing.

• Clear indication if iodised (with the iodine source specified).

• List of ingredients: salt, authorised anti-caking agents, iodide/iodate where present.

• Net weight, lot code, best-before date.

• Name and address of the responsible food business operator.

• Instructions for use or specific warnings where relevant.

Troubleshooting

• Lumping/caking → excessive humidity; improve sealing and storage conditions.

• Foreign odours → salt has absorbed environmental smells; always store away from detergents, strong spices, etc.

• Abnormal colour → impurities or contamination; check source and quality.

• Slow dissolution → very coarse crystals or partially hydrated/caked salt; grinding before use can help.

Sustainability and supply chain

• Solar sea-salt production has relatively low energy demand, though it requires large saltpan areas and careful ecosystem management.

• Rock-salt mining has a higher and more variable environmental impact, depending on extraction technologies and site management.

• Well-managed saltpans can act as valuable habitats for birds and other wildlife.

• Packaging (paper, cardboard, plastic) is often recyclable; selecting more sustainable materials reduces environmental footprint.

• Transparent supply chains distinguish food-grade salt from technical salt and support quality and safety.

Main INCI functions (cosmetics)
In cosmetic formulations, salt (e.g. Sodium Chloride, Maris Sal) is commonly used as:

• Viscosity regulator in shampoos and liquid cleansers.

• Astringent and toning agent in bath and spa products.

• Mechanical exfoliant in body scrubs and foot soaks.

• Stabilising agent in certain surfactant systems.

• Component of bath salts and wellness products for osmotic and sensory effects.

Conclusion
Salt is a fundamental food ingredient, indispensable for flavour, preservation and many technological functions in both domestic and industrial food preparation. Although it is essentially just sodium and chloride, it plays a crucial role in human physiology and in food processing. Conscious use, adherence to intake recommendations, proper storage and a well-controlled supply chain ensure quality, safety and a reasonable environmental impact.

Mini-glossary

• SFA – Saturated fatty acids (absent in salt; relevant to overall diet and cardiovascular risk).

• MUFA – Monounsaturated fatty acids (absent in salt; generally beneficial for lipid profile).

• PUFA – Polyunsaturated fatty acids (absent in salt; important for cell membranes and anti-inflammatory functions).

• GMP – Good Manufacturing Practices; industrial rules ensuring hygienic, correct production.

• HACCP – Hazard Analysis and Critical Control Points; preventive system for managing food-safety hazards.

• MRL – Maximum Residue Level; legal limit for contaminants/residues where applicable.

• BOD/COD – Biochemical/Chemical Oxygen Demand; indicators of organic load in wastewater used to assess environmental impact.

Studies

It is recommended to reduce salt consumption as it may cause damage to the cardiovascular system and increase the values of harmful LDL-cholesterol and cause hypertension, obesity and other serious diseases, but there is also diet salt on the market, with a lower percentage of sodium. 

'Salt killer'. This was the title of a well-known and authoritative American newspaper some time ago, explaining in detail the reasons why the overuse of common table salt could cause serious damage to health. In fact, salt is found naturally in almost all foods, so we absorb it daily, but heavy consumption can damage the human body. 

Hypertension: The relationship between salt and hypertension is unequivocal (1), and especially for the elderly, consumption must be reduced (2). For young people, the problems may be minor, but still exist (3). 

Obesity : High salt consumption is associated with overweight and obesity (4). 

Drinks and chips : The amount of salt in drinks, crisps etc. should be controlled, as the combination of salt and sugar (as not only sugar is included, but fructose, dextrose and others) can increase the risk associated with high salt consumption (5). 

Osteoporosis: In this study, despite press campaigns to advise against salt consumption, the results proved rather disappointing (6). The title of the article sums it up well: Important element, but invisible threat. 

So, to summarise, salt is an indispensable element, but one must be very careful not to abuse it. 

Salt is used as a food preservative

Cosmetics

In cosmetics, sodium chloride has the function of increasing the moisturising efficacy of ageing skin, is a thickener in shampoos and conditioners, but is also a co-factor in the eye irritation experienced with most shampoos and can cause dryness and itching of the scalp (7). Skin sodium is a pathophysiological feature of psoriasis (8), a chronic inflammatory skin disease, so high concentrations of sodium chloride should not be present in cosmetic products.

Medical

Sodium chloride is used in numerous medical and pharmaceutical applications: preservative, hypertonic salt solution in conjunction with dextran, production of interleukin-4, antibacterial with biocidal effect against Staphylococcus aureus (9).

Human epidermal stem cells can be stored in anhydrous sodium chloride at room temperature for months as well as some resident immune cells and skin fibroblasts (10).

In the following link you will find the best studies on salt and its health profile.

Salt studies

Sale ed obesità (italian)

Controllare il consumo del sale (italian)

Typical commercial product characteristics Sodium Chloride

Appearance	White powder
Boiling Point	1461 ºC
Melting Point	801°C(lit.)
Flash Point	1413°C
Density	2.165      1.199 g/mL at 20 °C
Refraction Index	n20/D 1.378
Water Solubility	360 g/L (20 ºC)
Storage	+15C to +30C
Potassium Iodate	35±15(20-50) mg/kg
Potassium ferrocyanide	≤10.0
Pb	≤1.0
As	≤0.5
F	≤5.0
Fe	≤0.0002
Ferrous cyanide	≤0.0001
Ba	≤15
Nitrogen	≤0.001
Sulfate	≤0.002
Nitrite	0
Safety

• Molecular Formula  NaCl    ClNa
• Molecular Weight     58.44
• Exact Mass    57.958622
• CAS  7647-14-5
• UNII    451W47IQ8X
• EC Number   231-598-3
• DSSTox Substance ID    DTXSID3021271    DTXSID6040379    DTXSID501033754
• IUPAC  sodium;chloride
• InChI=1S/ClH.Na/h1H;/q;+1/p-1
• InChl Key      FAPWRFPIFSIZLT-UHFFFAOYSA-M
• SMILES   [Na+].[Cl-]
• MDL number  MFCD00003477
• PubChem Substance ID    329824637
• ChEBI  26710
• RXCUI    9863  
• NSC   77364
• RTECS   VZ4725000
• NCI   C29974    C821
• Beilstein    3534976
• NACRES NA.21

Synonyms

• Sodium chloride
• Salt