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Natural preservatives
- 1. NATURAL PRESERVATIVES Definition ofPreservatives Any substance added to a processed food in order to extend its shelf life. Substances capable of inhibiting, retarding or arresting the process of fermentation, acidification or other deterioration of foods. A preservative is a substance or a chemical that is added to products such as food, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. Food preservation has been defined "as the science which deals with the process of prevention of decay or spoilage of food thus allowing it to be stored in a fit condition for future use". It has also been described as the state in which any food may be retained over a period of time without being contaminated by pathogenic organisms or chemicals and losing optimum qualities of colour, texture, flavor and nutritive value. History of FoodPreservation In early 19th century, remarkable innovations and researches in food preserving process were started. It was the time when Napoleon wars were going on and the soldiers and seamen fighting in the wars were living mainly on the salt-preserved meats. The salt-preserved meat does not have adequate nutritional value to fulfill the nutritional needs of Napoleon army. Also recurrent cases of Scurvy were emerging. Then, Napoleon was the first person who initiated the research for the new processes, techniques and mechanisms of preserving food for longer time. He also announced a prize of 12,000 franc pieces for the person who will discover new and safe methods and techniques of preserving food. A French chemist named Nicolas Appert was the winner of those 12,000 franc pieces offered by Napoleon. He presented his observation that food heated in sealed containers was preserved for a very long time or until the container is unopened and seal did not leak. This observation of Nicolas Appert was the decisive moment in the history of food preservation. After about fifty years, Louis Pasteur, a Frenchman, observed and studied the interaction between microorganisms (bacteria, microbes etc) and food spoilage. As, the time passed new researches and discoveries were accepted and rejected and new doors of researches in the field of food preservation were opened.
- 2. Importance of FoodPreservation By preserving the food the shelf-life of food is increased and many food products can be preserved for a longer time period. By preserving food, we can enjoy seasonal foods such as mangoes, peaches, pineapples etc throughout the year. It can also add variety of foods in diet. Partially cooked or processed food can also be preserved and such food products are time efficient and energy efficient too. It also decreases the wastage of food by preventing deterioration and spoilage of food. It is also important in preserving the nutrients present in the food. It is also used to preserve the appearance, color and texture of foods. ClassificationofFoodPreservatives Food preservatives are classified in the following two types: Natural preservatives or Class I preservatives Chemical or Class II preservatives Natural preservatives or Class I preservatives Natural preservatives are the traditional preservatives that stops or delays the growth of bacteria or microbes in the food for a specific time period. Chemical preservatives or Class II preservatives Chemical preservatives are the chemical substance that also stops or delays the growth of bacteria in the food, food spoilage and food discoloration for comparatively longer time period then natural preservatives. Natural preservatives Definition of Natural preservatives Natural preservatives are the traditional preservatives that stops or delays the growth of bacteria or microbes in the food for a specific time period. Natural preservatives have antioxidative, antimicrobial and antifungal properties which inhibit and prevent the growth of bacteria, fungus, molds and yeast. Examples of Natural preservatives Following are the natural preservatives which enhance the shelf life of food products.
- 3. Salt (SodiumChloride, NaCl) Sugar (Sucrose, C12H22O11) Vinegar (Acetic acid) Lemon juice (Citrus limon) Rosemary extract (Rosmarinus officinalis) Onion (Allium cepa) Olive oil (Olea europaea) Cloves (Syzygium aromaticum) Oregano (Origanum vulgare) Castor oil (Ricinus communis) Ginger (Zingiber officinale) Garlic (Allium sativum) Following is the role of above natural preservatives in food preservation. 1. Salt (Sodium Chloride, NaCl): Salt is one of the natural food preservative that is used to preserve meats and some vegetables for a longer time span. Microorganism such as bacteria, molds, yeast etc used to live and reproduce in aqueous medium. Salt protects the food from deterioration and spoilage by dehydrating the microbes by a process known as osmosis. Osmosis is defined as the movement of water across a semi-permeable membrane from a solution of lower solute concentration to a solution of higher solute concentration. Thus, salt provides protection to the food from bacteria, yeast and molds to reproduce. Salt is applied on the meat for preservation 2. Sugar (Sucrose, C12H22O11) Sugar is not only used as a sweetener but also a natural preservative which is readily available in almost every kitchen. Like salt, sugar also protects the food (especially fruits) from spoilage by the dehydration of microorganism by osmosis. Bacteria, molds and yeast require aqueous medium for reproduction. Most fruits and some vegetables are preserved by adding sugar.
- 4. Strawberries and Mangoesare preserved in sugar granules and sugar syrup respectively 3. Vinegar: (Acetic acid) Vinegar is made from the fermentation of sugar and water solutions. Household vinegar has ph of 2-3.Acetic acid is the major constituent of vinegar which kills the bacteria and other microbes present in the food causing the deterioration and food spoilage. Many vegetables in the form of pickles are preserved by the vinegar for long time period. Cucumbers and Olives are preserved by vinegar 4. Lemon juice: (Citrus limon) Lemon juice contains citric acid and vitamin C also known as Ascorbic acid. Microbes, bacteria, yeast and molds are unable to live and reproduce in acidic medium. As, lemon juice contains Ascorbic acid, it also inhibit the oxidation process of food because vitamin C is an antioxidant. Lemon juice is used in the preservation of fruits for a short period of time. Apple with and without lemon juice and Banana are dipped in Lemon juice
- 5. 5. Rosemary extracts:(Rosmarinus officinalis) Rosemary extract is obtained from the distillation of rosemary leaves. Rosemary extract contains carnosic acid and rosmaranic acid. Both of these are antioxidants and protect the food from spoilage. Rosemary contain about 20 – 24 antioxidants which have comparatively longer life span than other antioxidants. Rosemary extract is used to increase the shelf life of meats and to avoid the rancidity of fats and oils. As, Rosemary extract has a particular aroma so it is used in minute amounts i.e. 0.15% to 0.5% in food items as a preservative. Rosemary leaves and Rosemary extract 6. Onion: (Allium cepa) Onion or onion extracts are used in processed foods by replacing artificial preservatives. Onions have an antimicrobial and anti-oxidative property that’s why it prevents the oxidative deterioration of food and play an important role in preservation of foods. Quercetin is an antioxidant and flavonoid present in onions. Bacillus cereus, Staphylococcus aureus, Micrococcus luteus and Listeria monocytogenes are the microorganisms which cause deterioration in the food and the phenolic compounds in onion inhibit the growth of these bacteria. Besides preserving properties, it also has anti-inflammatory and anti-carcinogenic properties. Thus, onion not only increases the shelf life but also have many health benefits. Onion is added in tomato sauce as a preservative.
- 6. 7. Olive Oil:(Olea europaea) Food is spoiled when it comes in contact with oxygen and microorganisms. As, oil is greasy it provides insulation to the food and prevent the food from the attack of microbes and also the oxidative deterioration of food. Olive oil is mainly used for this purpose because it has many health benefits also. Meats and vegetables can be preserved by oils. Olive oil is applied on vegetables 8. Cloves (Syzygium aromaticum): Cloves are the spices used in food preparation. Syzygium aromaticum (cloves) also acts as a natural preservative. It is most commonly used in Chinese and Indian medicines and food items. for many years. Cloves contain high amounts of phenolic compounds which are antioxidants. The antioxidants present in the cloves prevent fungal and bacterial growth on the food. Anthocyanins, gallic acid, and quercetin are the antioxidants present in cloves. Syzygium aromaticum 9. Oregano (Origanum vulgare) Oregano is an Italian herb which is used in many Italian and Chinese foods. Besides its flavor it also has antioxidant, antibacterial and antifungal properties. Oregano can be used to preserve meats. Oregano can preserve meats but its drawback is that it can also change the flavor of the
- 7. product to someextent. Thymol and carvacrol present in oregano inhibit the growth of bacteria ie. Pseudomonas aeruginosa and Staphylococcus aureu. Origanum vulgare 10. Castor oil (Ricinus communis) Castor oil is used in food industries in preserving the color and taste of the product. Castor oil also acts as a mold inhibitor i.e. it prevent mold growth. It prevents rotting of wheat, rice, pulses and grains. It is most commonly used in India, Pakistan and China in preserving food grains. Ricinoleic acid is a fatty acid which is present in castor oil in huge amount about 90%. Ricinoleic acid is very effective and inhibits or prevents the growth and reproduction of viruses, bacteria, mold and yeast. Castor beans and castor oil 11. Ginger (Zingiber officinale) A rhizome, Zingiber officinale is used in food preservation. It has antimicrobial properties. A bacteria, salmonella is killed due to the antimicrobial properties of ginger. Also, a parasite, Anisakis is killed due to the antimicrobial properties of ginger. Salmonella, a rod-shaped bacteria
- 8. 12. Garlic (Alliumsativum) Allium sativum is a natural preservative. An experiment was conducted three times which proves that garlic can kill bacteria such as Escherichia coli and Salmonella. It can preserve meat by preventing meat spoilage due to bacterial growth. Escherichia coli Methods of Food preservation: Drying: Drying is the ancient method of food preservation. Drying is mostly used to preserve meats and fish in ancient times. The water content present in the meat is dehydrated and the chances of microbial and bacterial growth diminished. The meat products are exposed to heat which should not be more than 140 degrees. If the flesh is exposed to the temperature above 140 degrees than the protein fibers present in the meat hardened to an extent that it cannot be hydrated. Freezing: Freezing is a common method of preserving food domestically and commercially for a wide range of food items. Food is preserved by inhibiting the enzymatic and microbial activity by lowering the temperature. Nutritive value can be maintained by fast freezing at the temperature of -25 degrees. Vegetables and fruits are preserved by freezing for longer time period. Similarly, meats can also be preserved. Vacuum packaging: In vacuum packaging, food is packed in air tight bag, air tight jar or air tight bottle. Food when packed in any air tight container has no contact with oxygen. The bacteria present in the food will soon decay and there will be no food spoilage. Nuts are stored using vacuum packaging. Pickling: Pickling is also a very common method of food preservation. Food to be preserved are placed or dipped in an edible antimicrobial agent. Antimicrobial pickling agents commonly used are
- 9. vinegar, brine, oliveoil and many other vegetable oils. All these pickling agents inhibit the growth of bacteria and other microorganisms. Food which are commonly pickled includes cucumbers, mixed vegetables, peppers etc. Canning and bottling: Sealing cooked food in sterile bottle and cans is canning and bottling. Sterilization of container is done to kill or weaken all the microorganisms (bacteria). Food remains safe until the can or bottle is opened. As, the can is opened the shelf life of food will decrease or it may spoil. Jellying: Food is preserved in a material that solidifies in the form of gel. Jelly, marmalade, sauces of various fruits is generally preserved. Pectin is the jellying agent, found in the cell wall of plants. Sugar can also be used. Potting: A traditional method of food preservation introduced by the British people. It is used to preserve meat. Meat to be preserved is placed in the pot and sealed by the layer of fats. Smoking: Food can be cooked, flavored and preserved by exposing food to the smoke arises from burning woods. Smoking of meats and fish is common. Smoking is done by different methods such as, hot smoking, cold smoking, smoke roasting and smoke baking. As, a preservative smoking usually increase the risk of cancer. Sugaring: As, sugar is a natural preservative it is used in the form of crystals and syrup. Many fruits are preserved by sugaring such as strawberries, mangoes, peaches, pineapples etc. Sugar is also beneficial in providing glaze to the fruits. Salting: Salting is also a very common method of food preservation. It absorbs moisture from the food by osmosis and inhibits the growth of microbes, bacteria, yeast and molds. 20% of salt concentration in the food kills the microorganisms present in the food. Other methods of food preservation Burial in the ground Pulsed electric field processing Modified temperature
- 10. Controlled useof organism High pressure food preservation Modified atmosphere packaging Pasteurization Irradiation
- 11.