Preservatives are added to food to fight spoilage caused by bacteria, molds, fungus, and yeast. Preservatives can keep food fresher for longer periods of time, extending its shelf life. Food preservatives also are used to slow or prevent changes in color, flavor or texture and delay rancidity.
When it comes to preserving foods, there are two methods: physical and chemical. Drying, refrigerating and freezing are examples of physical preservation. Chemical preservation involves adding ingredients called additives to food in order to prevent oxidation, rancidity, bacterial growth, etc. There are both natural and synthetic preservatives that are used in food
Preservatives are classified as
1. Antioxidants
| Ascorbic acid | oxygen scavenger |
| butylated hydroxyanisole (BHA) | free radical scavenger |
| butylated hydroxytoluene (BHT) | free radical scavenger |
| citric acid | enzyme inhibitor/metal chelator |
| sulfites | enzyme inhibitor/oxygen scavenger |
| tertiary butylhydroquinone (TBHQ) | free radical scavenger |
| tocopherols | free radical scavenger |
2. Antimicrobials
| acetic acid | disrupts cell membrane function (bacteria, yeasts, some molds) |
| benzoic acid | disrupts cell membrane function/inhibits enzymes (molds, yeasts, some bacteria) |
| natamycin | binds sterol groups in fungal cell membrane (molds, yeasts) |
| nisin | disrupts cell membrane function (gram-positive bacteria, lactic acid-producing bacteria) |
| nitrates, nitrites | inhibits enzymes/disrupts cell membrane function (bacteria, primarily Clostridium botulinum) |
| propionic acid | disrupts cell membrane function (molds, some bacteria) |
| sorbic acid | disrupts cell membrane function/inhibits enzymes/inhibits bacterial spore germination (yeasts, molds, some bacteria) |
| sulfites and sulfur dioxide | inhibits enzymes/forms addition compounds (bacteria, yeasts, molds) |
