Chemistry in the Kitchen


What chemicals are used to preserve food?

There are two main types of food preservatives, those that prevent oxidation and those that prevent bacteria or fungi from growing. The first are appropriately named antioxidants, and these molecules work by reacting with oxygen themselves. Unsaturated fats are common targets of oxygen, which causes foods to become rancid. Antioxidants provide an even easier target for oxygen to attack, preventing O2 from wreaking havoc in other ways. Natural antioxidants include molecules like ascorbic acid (vitamin C); and there are also many unnatural antioxidants on the market.

The second class of preservatives are those that stop the growth of bacteria and fungi (like mold) from growing. Many of these preservatives are acidic molecules that can be absorbed into the cells of bacteria. If enough acid gets into the cell, basic biochemical functions (specifically fermentation of glucose) slow down enough that the cell dies, and your food stays fresh.


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