What are different types of preservatives?

 Preservatives currently used in food production are either extracted from natural sources or synthetically produced.1 For example, the preservative natamycin (E235), which is widely used in the surface treatment of cheese and sausages, can be naturally sourced from bacteria commonly present in soil.3 Natural preservatives can also be sourced from plants, animals, fungi, and algae.1 Furthermore, common kitchen staples like salt and sugar can also be used to naturally preserve food in certain cases, for example when making pickles or sauerkraut.4

Preservatives can be broadly categorized into so-called antimicrobial preservatives and antioxidant preservatives. However, many of the preservatives, like the sulphites used in wine and nitrates used in meat, serve both functions.1 Antimicrobial preservatives like sulphur compounds such as the sulphites (E220-228) are used to inhibit the growth of bacteria e.g., in wine, dried fruits, vegetables in vinegar or brine.5 Sorbic acid (E200) can be used for many different purposes, including the preservation of potato products, cheese and jam.6 Benzoic acid and its calcium, sodium or potassium salts (E210-213) are used as antibacterials and antifungals in foods such as pickled cucumbers, low sugar jams and jellies, dressings, condiments.7 Antioxidant preservatives are often used in minimally processed vegetable products such as ready-to-use salads, freshly cut fruit, and fresh juices, where browning is a significant concern.1 Ascorbic acid (E300) and citric acid (E330) can be used to prevent browning because it inhibits a certain enzyme that in the presence of oxygen creates brown pigments.