Preserving food is a method of storing both raw and cooked edible items for an extended period of time by using additives. These preservatives prevent decomposition of the food due to adverse chemical change or microbial action. This helps to save the appearance, texture, flavor, edibility, and nutritive value of the foods and also to save people from food poisoning.
Food preservatives can be either natural or man-made substances. Based on their action, they are broadly classified into three types. They are antimicrobial, antioxidant, and a third type, which targets the enzymes in the food itself. Antimicrobial preservatives inhibit the growth of microbes such as bacteria and fungi, whereas antioxidant variants inhibit the oxidation of fats, lipids, and other ingredients. The third type blocks the natural ripening and aging of the foodstuffs after harvest. In addition to using these preservatives, there are other healthy ways of preserving food. For example, processes such as drying, salting, smoking, pickling, and freezing can also preserve foods.
Natural food preservatives include substances such as salt, sugar, rosemary extract, and vinegar. Among these, salt, sugar, and vinegar are used as an ingredient rather than additives or preservatives. They are used in the recipe itself, hence they are also called traditional preservatives.
Salt: Salt has been used as a natural food preservative since ancient times, especially for meat. Salted meat can last for many years. The principle behind adding salt as a preservative is that it dehydrates microbes through the process of osmosis. Thus, it inhibits the bacteria that cause spoilage. Salt also protects food from yeast and mold.
Sugar: Sugar, an organic compound in the form of carbohydrate, has been used as a natural food preservative in many items. Sugar sweetens the product and inhibits the growth of microorganisms through the phenomenon of osmosis. Foods can be stored either in sugar syrup or in crystallized form, where the food is cooked in sugar till the point of crystallization. Sugar acts by drawing out water from the bacteria and other microorganisms, which either kills the bacteria or inhibits their growth.
Vinegar: Even though vinegar is acidic, it is not considered a harmful chemical or preservative and hence is used commonly as a natural food preservative. It is prepared by fermenting sugar and water solution beyond the alcohol stage. Nowadays, many people prefer homemade vinegar other than the ones that are sold. Vinegar contains acetic acid at 4-5% concentration. It is the acetic acid that kills microbes and hampers food spoilage. There are different types of vinegar depending upon the sugar base from which they have been made.
Rosemary Extract: Rosemary leaf extract, also known as rosemary oleoresin, has been used as a natural food preservative since a long time. It has been used traditionally for its pleasant aroma and flavor. It is prepared by distillation of rosemary leaves. They serve as a powerful antioxidant that prevents the oxidation of the food constituents, thus preserving the color and flavor of the food. Their antioxidant characteristic is due the presence of natural compounds such as phenolic diterpenes, carnosol, carnosic acid, and rosmarinic acid.
Many synthetic food additives are available in the market. These chemical formulations should be avoided as far as possible, as many of them are sold without proper testing. There are some artificial preservatives that are considered to be safe. However, it is observed that some toxins and carcinogens are found in them. So, take a note of the food preservatives to be avoided and go for only natural preservatives and properly certified chemical ones. It is recommended to follow food safety rules while handling, cooking, and preserving foods.