Use of salt in food preservations: Salt is perhaps most well known as a food preservative and flavouring agent. It has been used to preserve food for many thousands of years and is the most common seasoning. The reason why salt is such an effective preservative is that it draws moisture out of food. Dry foods are less likely to spoil as moisture is a key requirement for organisms that want to spoil the food. But salt also plays other, lesser-known roles in the food we eat as an essential nutrient, providing flavour and texture, and enhancing colour. For these reasons, salt is used in food production, which is why the sodium content of processed foods is so high. 

Salt has been used as a preservative for ages, and works to preserve food in two ways : 

• Salt dries food: Salt draws water out of food and dehydrates it. All living things require water and cannot grow in the absence of water, including the bacteria which can cause food poisoning. Salt is used to preserve beef jerky by keeping it dry, and it prevents butter from spoiling by drawing water out, leaving just the fat. 

• Salt kills microbes: In very high salt solutions, many microbes will rupture due to the difference in pressure between the outside and inside of the organism. High salt can also be toxic to internal processes of microbes, affecting DNA and enzymes. Solutions high in sugar also have the same effects on microbes, which is why it is used as a preservative of foods such as jams and jellies.