Download Preservatives and it's uses and more Lecture notes Food Science and Technology in PDF only on Docsity!
Preservative:
A preservative is a substance or a chemical that is added to products such as food, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of food borne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined. Food preservation prevents the growth of microorganisms, or other microorganisms, as well as slowing the oxidation of fats that cause rancidity. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation.
Types of Preservatives:
- Natural Food Preservatives
- Chemical Food Preservative
1. Natural Food Preservatives:
Natural food preservatives like salt, sugar, alcohol, vinegar etc. These are the traditional preservatives in food that are also used at home while making pickles, jams and juices etc. Also the freezing, boiling, smoking, salting are considered to be the natural ways of preserving food. The citrus food preservatives like citrus acid and ascorbic acid work on enzymes and disrupt their metabolism leading to the preservation. Sugar and salt are the earliest natural food preservatives that very efficiently drops the growth of bacteria in food. To preserve meat and fish, salt is still used as a natural food preservative.
a) Salt:
Salt is an essential one of the natural food preservative additives. It is mostly used for preserving meats and other non-vegetarian foods. Salt is instrumental providing protection from yeasts, molds and bacteria by dehydrating the microbes with a process called osmosis, curbing the growth of food spoiling bacteria and therefore enhancing the life of food being
preserved. Salt binds the water by entering the tiny food tissues, drawing out the moisture completely. Thus, reducing the chances of food getting spoiled for, longer than normal spans.
b) Sugar:
Sugar is also an everyday food ingredient. Other than being used as a sweetener, sugar is also among commonly used natural food preservatives. Sugar also uses the same concept of osmosis just like salt, where its soaks up all the moisture from the food being preserved and obstructing the growth of any food spoiling bacteria. Preserved foods are either stored in a sugar syrup or in the crystallized form. Sugar is usually used to preserve fruits like apple, plum, peach, pear, etc. The way these fruits are preserved, the sugar preservative content works as a sweeteners and enhanced the taste of these fruits overtime
2. Chemical food preservatives:
Chemical food preservatives are also being used for quite some time now. They seem to be the best and the most effective for a longer shelf life. Examples of chemical food preservatives are:
- Benzoates (such as sodium benzoate, benzoic acid)
- Nitrites (such as sodium nitrite)
- Sulphites (such as Sulphur dioxide)
- Sorbates (such as sodium sorbate, potassium sorbate
- Lactic Acid
- Carbon dioxide
- Antioxidant
- Emulsifiers
- Swetners
1. Benzoic acid
Benzoic acid in the form of its sodium salt constitutes one of the most common chemical food preservative. Sodium benzoate is a common preservative in acid or acidified foods such as fruit juices, syrups, jams and jellies, sauerkraut, pickles, preserves, fruit cocktails, etc. Yeasts are inhibited by benzoate to a greater extent than are moulds and bacteria.
2. Sorbic acid
Sorbic acid and its salts are practically tasteless and odourless in foods, when used at reasonable levels (< 0.3 %) and their antimicrobial activity is generally adequate. It is considered non-toxic and is metabolised; among other common food preservatives the WHO has set the highest acceptable daily intake (25 mg/kg body weight) for sorbic acid. Sorbates are used for mould and yeast inhibition in a variety of foods including fruits and vegetables, fruit juices, pickles, sauerkraut, syrups, jellies, jams, preserves, high moisture dehydrated fruits, etc
- Potassium sorbate, a white, fluffy powder, is very soluble in water (over 50%) and when added to acid foods it is hydrolysed to the acid form.
Antioxidants are also the chemical food preservatives that act as free radical scavengers. In this category of preservatives in food comes the vitamin C, BHA (butylated hydroxyanisole), bacterial growth inhibitors like sodium nitrite, sulfur dioxide and benzoic acid. Then there is ethanol that is a one of the chemical preservatives in food, wine and food stored in brandy. Unlike natural food preservatives some of the chemical food preservatives are harmful. Sulfur dioxide and nitrites are the examples. Sulfur dioxide causes irritation in bronchial tubes and nitrites are carcinogenic.
Approval of preservatives:
The FDA has jurisdiction over all preservatives, with the Food Safety and Inspection Service sharing responsibility for the safety of food additives used in meat, poultry and egg products. The FDA mandates that preservatives not be used in such a way as to conceal damage or inferiority, make the food appear better than it is or adversely affect the nutritive value of the food. Food additives approved for use as preservatives are listed in the U.S. Code of Federal Regulations. According to the regulatory authorities, preservatives are generally recognized as safe, or GRAS, in the quantities in which they are allowed in individual food products. “Safe” for food additives is defined to mean “a reasonable certainty in the minds of competent scientists that the substance is not harmful under the intended conditions of use.” Still, there are some preservatives of concern. Harmful food preservatives have been accused of many health hazards ranging from mild headaches to most serious diseases like cancer. However, not all food preservatives are harmful, especially if they have been manufactured in controlled situations and used in food items in amounts permissible by food laws.
