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Understanding food chemistry; Preservatives, additives
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Wednesday, 01 October, 2014, 08 : 00 AM [IST]
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Dr Vivek Srivastav
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fiogf49gjkf0d Food is any substance or material eaten or drunk to provide nutritional support for the body or for pleasure. It usually is of plant or animal origin, contains essential nutrients such as carbohydrates, fats, proteins, vitamins, or minerals, and is ingested and assimilated by an organism to produce energy, stimulate growth and maintain life.
Food chemistry is the study of chemical processes and interactions of all biological and non-biological components of foods. The biological substances include meat, poultry, lettuce, beer, and milk as examples. It is similar to biochemistry in its main components such as carbohydrates, lipids, and protein, but it also includes areas such as water, vitamins, minerals, enzymes, food additives, flavours, and colours.
Food storage is both a traditional domestic skill and is important industrially. Food is stored by almost every human society and by many animals. Storing of food has several main purposes: preparation for periods of scarcity or famine, taking advantage of short-term surplus of food as at harvest time, enabling a better balanced diet throughout the year, preparing for special events and celebrations, planning for catastrophe or emergency, religious reasons (LDS Church leaders council church members to store food) and protection against predators or others.
Food refrigerated at the earliest possible moment, and even so have a shelf life of two weeks or less.
Chemistry of Food
Food chemistry or chemistry is the study of chemical processes and interactions of all biological and non-biological components of foods. It also deals with the production, processing, distribution, preparation, evaluation, and utilisation of food. Food chemists work with plants that have been harvested for food, and animals that have been slaughtered for food. Food chemists are concerned with how these food products are processed, prepared, and distributed. For example, to address consumer demands, some food chemists are involved with finding fat and sugar substitutes that do not alter food taste and texture. Basic food chemistry deals with the three primary components in food: carbohydrates, lipids and proteins.
Carbohydrates make up a group of chemical compounds found in plant and animal cells. They have an empirical formula CnH2nOn or CH2O. Since this formula is essentially a combination of carbon and water these materials are called “hydrates of carbon or carbohydrates.” Carbohydrates are the primary products of plant photosynthesis, and are consumed as fuel by plants and animals. Food carbohydrates include the simple carbohydrates (sugars) and complex carbohydrates (starches and fibre). Lipids include fats, oils, waxes, and cholesterol. In the body, fat serves as a source of energy, a thermal insulator, and a cushion around organs; and it is an important component of the cell. Since fats have 2.25 times the energy content of carbohydrates and proteins, most people try to limit their intake of dietary fat to avoid becoming overweight. In most instances, fats are from animal products - meats, milk products, eggs, seafood and oils are from plants - nuts, olives, and seeds. We use lipids for flavour, to cook foods, and to improve the texture of foods.
Proteins are important components of food. Every cell requires protein for structure and function. Proteins are complex polymers composed of amino acids. There are 20 amino acids found in the body. Eight of these are essential for adults and children, and nine are essential for infants.
Essential means that we cannot synthesise them in large enough quantities for growth and repair of our bodies, and therefore, they must be included in our diet. Proteins consist of long chains of 100-500 amino acids that form into three-dimensional structures, their native state. When you change the native state of the protein, you change the three-dimensional structure, which is referred to as denaturation. Factors that cause denaturation include heating, acid, beating and freezing.
Preservation of Food
It is the process of treating and handling food to stop or greatly slow down spoilage (loss of quality, edibility or nutritive value) caused or accelerated by micro-organisms. Some methods, however, use benign bacteria, yeasts or fungi to add specific qualities and to preserve food (e.g. cheese, wine). Maintaining or creating nutritional value, texture and flavour is important in preserving its value as food. This is culturally dependent, as what qualifies as food fit for humans in one culture may not qualify in another culture. Preservation usually involves preventing the growth of bacteria, fungi, and other microorganisms, as well as retarding the oxidation of fats which cause rancidity. It also includes processes used to inhibit natural ageing and discolouration that can occur during food preparation such as the enzymatic browning reaction in apples after they are cut.
Classification of Food Preservation
Some preservation methods require the food to be sealed after treatment to prevent recontamination with microbes; others, such as drying, allow food to be stored without any special containment for long periods. Common methods of applying these processes include drying, spray drying, freeze drying, freezing, vacuum-packing, canning, preserving in syrup, sugar crystallisation, food irradiation, and adding preservatives or inert gases such as carbon dioxide. Other methods that not only help to preserve food, but also add flavour, include pickling, salting, smoking, preserving in syrup or alcohol, sugar crystallisation and curing. Preservation processes include:
- Heating to kill or denature microorganisms (e.g. boiling)
- Oxidation (e.g. use of sulfur dioxide)
- Toxic inhibition (e.g. smoking, use of carbon dioxide, vinegar, alcohol etc.)
- Dehydration (drying)
- Osmotic inhibition (e.g. use of syrups)
- Low temperature inactivation (e.g. freezing)
- Ultra high water pressure (e.g. fresherised, a kind of “cold” pasteurisation, the pressure kills naturally occurring pathogens, which cause food deterioration and affect food safety). These methods include:
i. Drying: One of the oldest methods of food preservation is by drying, which reduces water activity sufficiently to prevent or delay bacterial growth. Drying also reduces weight.
ii. Freezing: Freezing is also one of the most commonly used processes commercially and domestically for preserving a very wide range of food including prepared food stuffs which would not have required freezing in their unprepared state. For example, potato waffles are stored in the freezer, but potatoes themselves require only a cool dark place to ensure many months’ storage. Cold stores provide large volume, long-term storage for strategic food stocks held in case of national emergency in many countries.
iii. Vacuum packing: Vacuum packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, slowing spoiling. Vacuum packing is commonly used for storing nuts to reduce loss of flavour from oxidation.
iv. Salt: Salting or curing draws moisture from the meat through a process of osmosis. Meat is cured with salt or sugar, or a combination of the two. Nitrates and nitrites are also often used to cure meat and contribute the characteristic pink colour, as well as inhibition of Clostridium botulinum.
v. Sugar: Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallised form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel), angelica and ginger. A modification of this process produces glace fruit such as glace cherries where the fruit is preserved in sugar but is then extracted from the syrup and sold, the preservation being maintained by the sugar content of the fruit and the superficial coating of syrup. The use of sugar is often combined with alcohol for preservation of luxury products such as fruit in brandy or other spirits.
vi. Pickling: Pickling is a method of preserving food in an edible anti-microbial liquid. Pickling can be broadly categorised as chemical pickling for example, in chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other microorganisms. Typical pickling agents include brine (high in salt), vinegar, alcohol, and vegetable oil, especially olive oil but also many other oils. Many chemical pickling processes also involve heating or boiling so that the food being preserved becomes saturated with the pickling agent. Common chemically pickled foods include cucumbers, peppers, corned beef, herring, and eggs, as well mixed vegetables such as piccalilli. In fermentation pickling, the food itself produces the preservation agent, typically by a process that produces lactic acid. Fermented pickles include sauerkraut, nukazuke, kimchi, surstromming, and curtido. Some pickled cucumbers are also fermented.
vii. Lye: Sodium hydroxide (lye) makes food too alkaline for bacterial growth. Lye will saponify fats in the food, which will change its flavour and texture. Lutefisk uses lye in its preparation, as do some olive recipes. Modern recipes for century eggs also call for lye. Masa harina and hominy use agricultural lime in their preparation and this is often misheard as ‘lye’.
viii. Canning and bottling: Canning involves cooking food, sealing it in sterile cans or jars, and boiling the containers to kill or weaken any remaining bacteria as a form of sterilisation. It was invented by Nicolas Appert. Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits such as tomatoes require longer boiling and addition of other acidic elements. Low acid foods, such as vegetables and meats require pressure canning. Food preserved by canning or bottling is at immediate risk of spoilage once the can or bottle has been opened. Lack of quality control in the canning process may allow ingress of water or microorganisms. Most such failures are rapidly detected as decomposition within the can causing gas production and the can will swell or burst. However, there have been examples of poor manufacture (underprocessing) and poor hygiene allowing contamination of canned food by the obligate anaerobe Clostridium botulinum, which produces an acute toxin within the food, leading to severe illness or death. This organism produces no gas or obvious taste and remains undetected by taste or smell. Its toxin is denatured by cooking, though, cooked mushrooms, handled poorly and then canned, can support the growth of Staphylococcus aureus, which produces a toxin that is not destroyed by canning or subsequent reheating
ix. Jellying: Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include gelatine, agar, maize flour and arrowroot flour. Some foods naturally form a protein gel when cooked such as eels and elvers, and sipunculid worms which are a delicacy in the town of Xiamen in Fujian province of the People’s Republic of China. Jellied eels are a delicacy in the East End of London where they are eaten with mashed potatoes. Potted meats in aspic, (a gel made from gelatine and clarified meat broth) were a common way of serving meat off-cuts in the UK until the 1950s.
Many jugged meats are also jellied. Fruit preserved by jellying is known as jelly, marmalade, or fruit preserves. In this case, the jellying agent is usually pectin, either added during cooking or arising naturally from the fruit. Most preserved fruit is also sugared in jars. Heating, packaging and acid and sugar provide the preservation.
x. Potting: A traditional British way of preserving meat (particularly shrimp) is by setting it in a pot and sealing it with a layer of fat. Also common is potted chicken liver.
xi. Jugging: Meat can be preserved by jugging, the process of stewing the meat (commonly game or fish) in a covered earthenware jug or casserole. The animal to be jugged is usually cut into pieces, placed into a tightly-sealed jug with brine or gravy, and stewed. Red wine and/or the animal’s own blood is sometimes added to the cooking liquid. Jugging was a popular method of preserving meat up until the middle of the 20th century.
xii. Irradiation: Irradiation of food is the exposure of food to ionising radiation; either high-energy electron X- rays from accelerators, or by gamma rays (emitted from radioactive sources as Cobalt-60 or Caesium-137). The treatment has a range of effects, including killing of bacteria, moulds and insect pests, reducing the ripening and spoiling of fruits, and at higher doses including sterility. The technology may be compared to pasteurisation; it is sometimes called ‘cold pasteurisation,’ as the product is not heated. Irradiation is not effective against viruses or prions; it cannot eliminate toxins already formed by microorganisms, and is only useful for food of high initial quality. The radiation process is unrelated to nuclear energy, but it may use the radiation emitted from radioactive nuclides produced in nuclear reactors. Ionising radiation is hazardous to life (hence its usefulness in sterilisation); for this reason irradiation facilities have a heavily shielded irradiation room where the process takes place. Radiation safety procedures ensure that neither the workers in such facility nor the environment receive any radiation dose from the facility. Irradiated food does not become radioactive, and national and international expert bodies have declared food irradiation as wholesome. However, the wholesomeness of consuming such food is disputed by opponents and consumer organisations. National and international expert bodies have declared food irradiation as ‘wholesome,’ UN organisations such as WHO and FAO are endorsing use of food irradiation. International legislations on whether food may be irradiated or not varies worldwide from no regulation to full banning. It is estimated that about 500,000 tonne of food items are irradiated per year worldwide in over 40 countries. These are mainly spices and condiments with an increasing segment of fresh fruit irradiated for fruit fly quarantine.
xiii. Modified atmosphere: Modifying atmosphere is a way to preserve food by operating on the atmosphere around it. Salad crops which are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere modified to reduce the oxygen (O2) concentration and increase the carbon dioxide (CO2) concentration. There is concern that although salad vegetables retain their appearance and texture in such conditions, this method of preservation may not retain nutrients, especially vitamins. Grains may be preserved using carbon dioxide. A block of dry ice is placed in the bottom and the can is filled with grain. The can is then “burped” of excess gas. The carbon dioxide from the sublimation of the dry ice prevents insects, mould, and oxidation from damaging the grain. Grain stored in this way can remain edible for five years. Nitrogen gas (N2) at concentrations of 98% or higher is also used effectively to kill insects in grain through hypoxia. However, carbon dioxide has an advantage in this respect as it kills organisms through both hypoxia and hypercarbia, requiring concentrations of only 80%, or so. This makes carbon dioxide preferable for fumigation in situations where a hermetic seal cannot be maintained.
xiv. Burial in the ground: Burial of food can preserve food due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or desiccants in the soil. Burial may be combined with other methods such as salting or fermentation. Many root vegetables are very resistant to spoilage and require no other preservation other than storage in cool dark conditions, for example by burial in the ground, such as in a storage clamp. Century eggs are created by placing eggs in alkaline mud (or other alkaline substance) resulting in their “inorganic” fermentation through raised pH instead of spoiling. The fermentation preserves them and breaks down some of the complex, less flavourful proteins and fats into simpler more flavourful ones. Most foods can be preserved in soil that is very dry and salty (thus a desiccant), or soil that is frozen.
xv. Controlled use of microorganism: Some foods, such as many cheeses, wines, and beers will keep for a long time because their production uses specific microorganisms that combat spoilage from other less benign organisms. These microorganisms keep pathogens in check by creating an environment toxic for themselves and other microorganisms by producing acid or alcohol. Starter microorganisms, salt, hops, controlled (usually cool) temperatures, controlled (usually low) levels of oxygen and/or other methods are used to create the specific controlled conditions that will support the desirable organisms that produce food fit for human consumption.
xvi. High Pressure Food Preservation: High pressure food preservation refers to high pressure used for food preservation.
“Pressed inside a vessel exerting 70,000 pounds per square inch or more, food can be processed so that it retains its fresh appearance, flavour, texture and nutrients while disabling harmful microorganism and slowing spoilage.” By 2001, adequate commercial equipment was developed so that by 2005 the process was being used for products ranging from orange juice to guacamole to deli meats and widely sold.
Food Preservatives
Preservatives may be added to food to prevent the growth of fungi. Preservative food additives can be used alone or in conjunction with other methods of food preservation. Preservatives may be antimicrobial preservatives, which inhibit the growth of bacteria or fungi, including mould, or antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents. Common antimicrobial preservatives include calcium propionate, sodium nitrate, sodium nitrite, sulfites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.) and disodium. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specialising in food science, toxicology, and biology.
Natural substances such as salt, sugar, vinegar, alcohol, and diatomaceous earth are also used as traditional preservatives. Certain processes such as freezing, pickling, smoking and salting can also be used to preserve food. Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolise after they are cut. For instance, citric and ascorbic acids from lemon or other citrus juice can inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown. Most foods contain enzymes or natural chemicals, such as acids or alcohols that cause them to begin to lose desirable characteristics almost immediately after harvest or preparation. In addition, a host of environmental factors, such as heat and the presence of microorganisms, acts to change foodstuffs in ways that may harm the food product.
Food preservation traditionally has three goals: the preservation of nutritional characteristics, the preservation of appearance, and a prolongation of the time that the food can be stored. Traditional methods of preservation usually aim to exclude air, moisture, and microorganisms, or to provide environments in which organisms that might cause spoilage cannot survive. Among the earliest preservatives were sugar and salt (NaCl), which produced food environment of high osmotic pressure that denied bacteria the aqueous surroundings they needed to live and reproduce. Jams and jellies are preserved as solutions of high sugar content, and many meats (e.g., hams) and fish are still preserved by salting. Unlike other microorganisms, moulds can often withstand the effects of high salt or sugar concentrations in foods. Fortunately, they seldom cause illness. Early methods of air removal included the sealing of foods inside containers (such as jars), or the covering of food surfaces with hot paraffin. The invention of canning by Nicolas Appert enabled commercial preparations of foodstuffs. In response to a prize offered by Napoleon in 1795, Appert developed a method of canning and preserving fruits and vegetables in glass containers for sea voyages. His process was used commercially in 1910 by Peter Durand in England, using metal cans. During the earliest days of canning, some persons (including some Arctic explorers) probably died as a result of exposure to the lead that was once used to solder cans.
Modern techniques of air removal include vacuum sealing and the use of plastic wrappings. Chemical preservatives include free radical scavengers (also known as antioxidants), such as vitamin C and compounds such as BHA (butylated hydroxyanisole), and bacterial growth inhibitors, such as benzoic acid, sulfur dioxide, and sodium nitrite (NaNO2). Ethanol (CH3CH2OH) has long been used as a preservative, both of itself (as in wine), and of other foods (e.g. fruits stored in brandy).
Some chemical preservatives may be harmful: Sulfur dioxide (often used to preserve wines) is irritating to the bronchial tubes of persons who have asthma, and nitrites have been implicated as carcinogens.
After Louis Pasteur proved that it was the presence of bacteria that caused food to spoil, there was a tendency to consider all microorganisms harmful. But in fact, microbial action is responsible for the production and preservation of some foods. The action of microbes is a part of the production of cheese and some flavouring agents. Sauerkraut is both processed. The irradiation of foods has the advantage of enabling food packaging and preparation in which there is less person-to-food contact, thus decreasing the possibility of contamination and decreasing the need for chemical preservatives, some of which may be harmful. The ionising radiation that is used to irradiate foods, wherein the foods are exposed to bursts of high-intensity x-rays or streams of electrons, disrupts bacterial DNA. Some persons have objected to the irradiation of foods because of an (unfounded) fear of radioactivity. As pathogens such as virulent strains of coliform bacteria have caused food poisoning, the irradiation of animal carcasses and, in particular, of hamburger during its preparation has become more desirable. Irradiation currently extends the shelf life of foods such as strawberries. Irradiation does not make foods radioactive, but may cause changes in food colour or texture.
Food Additives
In its broadest sense, a food additive is any substance added to food. Legally, the term refers to any substance - the intended use of which results or may reasonably be expected to result - directly or indirectly - in its becoming a component or otherwise affecting the characteristics of any food. This definition includes any substance used in the production, processing, treatment, packaging, transportation or storage of food. Food additives are also substances added to food to preserve flavour or enhance its taste and appearance. Some additives have been used for centuries; for example, preserving food by pickling (with vinegar), salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines. With the advent of processed foods in the second half of the 20th century, many more additives have been introduced, of both natural and artificial origin. Food Additives are defined by the United States Food and Drug Administration (FDA) as “any substance, the intended use of which results or may reasonably be expected to result, directly or indirectly, in its becoming a component or otherwise affecting the characteristics of any food.” In other words, an additive is any substance that is added to food. Direct additives are those that are intentionally added to foods for a specific purpose while indirect additives are those to which the food is exposed during processing, packaging, or storing. If a substance is added to a food for a specific purpose, it is referred to as a direct additive. For example, the low-calorie sweetener aspartame, which is used in beverages, puddings, yoghurt, chewing gum and other foods, is considered a direct additive. Many direct additives are identified on the ingredient label of foods. Indirect food additives are those that become part of the food in trace amounts due to its packaging, storage or other handling. For instance, minute amounts of packaging substances may find their way into foods during storage.
Food Additives Classification
a) Antimicrobial agents, which prevent spoilage of food by mould or microorganisms. These include not only vinegar and salt, but also compounds such as calcium propionate and sorbic acid, which are used in products such as baked goods, salad dressings, cheeses, margarines, and pickled foods.
b) Antioxidants, which prevent rancidity in foods containing fats and damage to foods caused by oxygen. Examples of antioxidants include vitamin C, vitamin E, BHA (butylated hydroxyl anisole), BHT (butylated hydroxytolene), and propyl gallate.
c) Artificial colours, which are intended to make food more appealing and to provide certain foods with a colour that humans associate with a particular flavour (e.g. red for cherry, green for lime).
d) Artificial flavours and flavour enhancers are the largest class of additives; its function is to make food taste better, or to give it a specific taste. Examples are salt, sugar, and vanilla, which are used to complement the flavour of certain foods. Synthetic flavouring agents, such as benzaldehyde for cherry or almond flavour, may be used to simulate natural flavours. Flavour enhancers, such as monosodium glutamate (MSG) intensifying the flavour of other compounds in a food.
e) Bleaching agents, such as peroxides, are used to whiten foods such as wheat flour and cheese.
f) Chelating agents, which are used to prevent discoloration, flavour changes, and rancidity that might occur during the processing of foods. Examples are citric acid, malic acid, and tartaric acid.
g) Nutrient additives, including vitamins and minerals are added to foods during enrichment or fortification. For example, milk is fortified with vitamin D, and rice is enriched with thiamin, riboflavin, and niacin.
h) Thickening and stabilising agents, which function to alter the texture of a food. Examples include the emulsifier lecithin, which keeps oil and vinegar blended in salad dressings, and carrageen - used as a thickener in ice creams and low-calorie jellies.
Groups
Food additives can be divided into several groups, although there is some overlap between them.
Acids: Food acids are added to make flavours “sharper,” and also act as preservatives and antioxidants. Common food acids include vinegar, citric acid, tartaric acid, malic acid, fumaric acid, and lactic acid.
Acidity regulators: Acidity regulators are used to change or otherwise control the acidity and alkalinity of foods.
Anticaking agents: Anticaking agents keep powders such as milk powder from caking or sticking.
Antifoaming agents: Antifoaming agents reduce or prevent foaming in foods.
Antioxidants: Antioxidants such as vitamin C act as preservatives by inhibiting the effects of oxygen on food, and can be beneficial to health.
Bulking agents: Bulking agents such as starch are additives that increase the bulk of a food without affecting its nutritional value.
Food colouring: Colourings are added to food to replace colours lost during preparation, or to make food look more attractive and appealing.
Colour retention agents: In contrast to colourings, colour retention agents are used to preserve a food’s existing colour.
Emulsifiers: Emulsifiers allow water and oil to remain mixed together in an emulsion, as in mayonnaise, ice cream, and homogenised milk.
Flavours: Flavours are additives that give food a particular taste or smell, and may be derived from natural ingredients or created artificially. Flavour enhancers: Flavour enhancers enhance a food’s existing flavours. They may be extracted from natural sources (through distillation, solvent extraction, maceration, among other methods) or created artificially.
Flour treatment agents: Flour treatment agents are added to flour to improve its colour or its use in baking.
Glazing agents: Glazing agents provide a shiny appearance or protective coating to foods.
Humectants: Humectants prevent foods from drying out.
Tracer gas: Tracer gas allows for package integrity testing preventing foods from being exposed to atmosphere, thus guaranteeing shelf life.
Stabilisers: Stabilisers, thickeners and gelling agents, like agar or pectin (used in jam for example) give foods a firmer texture. While they are not true emulsifiers, they help to stabilise emulsions.
Sweeteners: Sweeteners are added to foods for flavouring. Sweeteners other than sugar are added to keep the food energy (calories) low, or because they have beneficial effects for diabetes mellitus and tooth decay and diarrhoea.
Thickeners: Thickeners are substances which, when added to the mixture, increase its viscosity without substantially modifying its other properties.
Nowadays, most people tend to eat the ready-made food available in the market, rather than preparing it at home. Such foods contain some kind of additives and preservatives, so that their quality and flavour is maintained and they are not spoiled by bacteria and yeasts. More than 3,000 additives and preservatives are available in the market, which are used as antioxidants and antimicrobial agents. Salt and sugar are the most commonly used additives. Some of the commonly used food additives and preservatives are aluminum silicate, amino acid compounds, ammonium carbonates, sodium nitrate, propyl gallate, butylated hydrozyl toluene (BHT), butylated hydroxyanisole (BHA), monosodium glutamate, white sugar, potassium bromate, potassium sorbate, sodium benzoate, and so on. Some artificial colours are also added to the foods to give them an appealing look. These colouring substances are erythrosine (red), cantaxanthin (orange), amaranth (Azoic red), tartrazine (Azoic yellow) and annatto bixine (yellow orange). When the food is to be stored for a prolonged period, use of additives and preservatives is essential in order to maintain its quality and flavour. The excess water in the foods can cause the growth of bacteria, fungi and yeasts. Use of additives and preservatives prevents spoiling of the foods due to the growth of bacteria and fungi. Additives and preservatives maintain the quality and consistency of the foods. They also maintain palatability and wholesomeness of the food, improve or maintain its nutritional value, control appropriate pH, provide leavening and colour, and enhance its flavour.
Chemistry of Food Additives
When we need to store any food for a longer time, it should be properly processed. During this processing, some substances and chemicals, known as additives, are added to the food. In addition, we also need to add some preservatives in order to prevent the food from spoiling. Direct additives are intentionally added to foods for a particular purpose. Indirect additives are added to the food during its processing, packaging and storage. Food additives require the appropriate machinery; dispensing and storing equipment, whether one produces chemical food additives, or rely on food preservative suppliers to deliver additives and preservatives for baked goods or beverages. In the food preservatives industry, the industry considers supplies that align with the need for using food additives in food products. In other words, supplies and other equipment for food additives must be beneficial in maintaining freshness, consistency, texture, taste, colour and nutrient levels that help sell food products. Supplies for food additives include liquid and solid separation equipment, food preservation presses, industrial mixers, homogenisers, pasteurisers and dispensers. Conveyors, storage and processing tanks, and vacuum tumblers that marinate or cure meats are also common equipment used for preservatives in food. Chemical food additives such as corn starch, potassium sorbate and sodium nitrate are usually available as syrup, crystals or powders that must be ordered from food preservative suppliers.
Effect of Additives in Food
Some modern synthetic preservatives have become controversial because they have been shown to cause respiratory or other health problems. Some studies point to synthetic preservatives and artificial colouring agents aggravating ADD and ADHD (Attention Deficit Disorder and Attention Deficit Hyperactivity Disorder) symptoms in those affected [35]. Older studies were inconclusive, quite possibly due to inadequate clinical methods of measuring offending behaviour. Parental reports were more accurate indicators of the presence of additives than clinical tests.Several major studies show academic performance increased and disciplinary problems decreased in large non-ADD student populations when artificial ingredients, including preservatives were eliminated from school food programmes. Allergic preservatives in food or medicine can cause an aphylactic shock in susceptible individuals, a condition which is often fatal within minutes without emergency treatment. It is almost a certainty that few really know what it is, that is part of their foodstuffs, and yet may present threats and danger. Essentially, there are two main sources of dangerous or threatening additives. The first is those that are put in as part of the processing operation. These include the colourings, preservatives, flavours and flavour enhancers, sweeteners, texture agents and processing agents. Details of these must be included on the labelling and can be identified with a little knowledge and some attention to the information provided by the manufacturer. Ideally, food that has no additives at all is to be preferred and especially if it is to be used to feed children. Far too many of our young are sensitised through these additives and this can lead to allergies and such conditions as Attention Deficit Disorder and Hyperactivity
Significance of Preservatives, Additives
The importance of preserving food is that, it lengthens the shelf life of a food and it slows down the spoilage of food which is caused by microorganisms present in the container or the hands that held it before putting it inside a container. The importance of food preservation is so that the food cannot be spoilt or can cause illness. Although preservatives are essential to maintain food safety, too much of a good thing is not healthy. Besides allergies, these foods may cause stomach pains, vomiting, breathing problems, hives and skin rashes. Some of the worst additives include benzoates, which can cause skin rashes, asthma and perhaps brain damage. Bromates can cause nausea and diarrhoea. Saccharin may lead to toxic reactions that impact the gastrointestinal tract and heart, as well as cause tumours and bladder cancer. Red Dye 40 may result in certain birth defects. Sodium chloride can lead to high blood pressure, kidney failure, stroke and heart attack. Such problems are why some doctors are now saying it is better to have a soda with sugar than a diet soda with additives.
Food Additives - Advantages
Food additives play a vital role in today’s food supply. They allow our growing urban population to have a variety of foods year-round. And, they make possible an array of convenience foods without the inconvenience of daily shopping. Food additives perform a variety of useful functions in foods that are often taken for granted. Since most people no longer live on farms, additives help keep food wholesome and appealing while en route to markets sometimes thousands of miles away from where it is grown or manufactured. Additives also improve the nutritional value of certain foods and can make them more appealing by improving their taste, texture, consistency or colour.
Additives are used in foods for five main reasons:
i) To maintain product consistency. Emulsifiers give products a consistent texture and prevent them from separating. Stabilisers and thickeners give smooth uniform texture. Anti-caking agents help substances such as salt to flow freely.
ii) To improve or maintain nutritional value, vitamins and minerals are added to many common foods such as milk, flour, cereal and margarine to make up for those likely to be lacking in a person’s diet or lost in processing. Such fortification and enrichment has helped reduce malnutrition among the US population. All products containing added nutrients must be appropriately labelled.
iii) To maintain palatability and wholesomeness.
Preservatives retard product spoilage caused by mould, air, bacteria, fungi or yeast. Bacterial contamination can cause food-borne illness, including life-threatening botulism. Antioxidants are preservatives that prevent fats and oils in baked goods and other foods from becoming rancid or developing an off-flavour. They also prevent cut fresh fruits such as apples from turning brown when exposed to air.
iv) To provide leavening or control acidity/alkalinity.
Leavening agents that release acids when heated can react with baking soda to help cakes, biscuits and other baked goods to rise during baking. Other additives help to modify the acidity and alkalinity of foods for proper flavour, taste and colour.
v) To enhance flavour or impact desired colour. Many spices, natural and synthetic flavours enhance the taste of foods. Colours, likewise, enhance the appearance of certain foods to meet consumer expectations.
Additives and preservatives are used to maintain product consistency and quality, improve or maintain nutritional value, maintain palatability and wholesomeness, provide leavening, control pH, enhance flavour, or provide colour.
(The author is chief scientific offiicer, Zeon Lifesciences Ltd, Uttar Pradesh. He can be contacted at vivek.srivastav@zeonlifesciences.com)
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