K T H Farrer. Cambridge World History of Food. Editor: Kenneth F Kiple & Kriemhild Conee Ornelas, Volume 2, Cambridge University Press, 2000.
Foods are biological products and, therefore, incorporate complex physical and biochemical systems. Many vegetables, fruits, and (sometimes) meat and fish are eaten raw, but in general they are cooked. And cooking induces profound chemical and physical changes. Some changes, such as the denaturation of protein and the gelation of starch, render food more digestible and are beneficial; others, by improving appearance, color, flavor, and texture, are also desirable. But some that cause heat damage to proteins, the loss of vitamins, or the formation of carcinogens on the surfaces of roast and barbecued meats are deleterious. Cooking leads to the use of one system, or a component of it, in the establishment of another. An example would be the role of egg yolks in emulsifying oil and water (vinegar) to make mayonnaise and to color it. Cooking also permits the use of major and minor ingredients and, thus, infinite variation in the final dish, but it also opens the way for the entry into food of nonfood substances derived from utensils and containers, and from the kitchen itself.
Food processors operate highly organized and sophisticated kitchens, and they apply detailed scientific knowledge of the raw materials to the production and packaging of products in response to market demands for variety, safety, wholesomeness, nutrition, and reasonable price. In effect, food processors are “super-cooks,” but if in making mayonnaise they use lecithin (emulsifier) and beta-carotene (color) instead of egg yolk, or if they add acetic or citric acids instead of vinegar, then they are using additives.
Put simply, a food additive is a substance deliberately added to food by the processor to facilitate processing or to improve appearance, texture, flavor, keeping quality, or nutritional value. By contrast, any unwanted substance that finds its way into food is a contaminant. This may be defined even more widely as a substance that is not normally present in that food in its natural form; or is present in concentrations not normally found; or is not permitted under the food regulations to be present; or, being an additive as defined under the regulations, exceeds the concentration permitted.
Unfortunately, practice denies such simplicity, and the Codex Alimentarius Commission uses the following definition:
“Food additive” means any substance not normally consumed as food by itself or not normally used as a typical ingredient of the food, whether or not it has nutritive value, the intentional addition of which to food for a technological (including organoleptic) purpose in the manufacture, processing, preparation, treatment, packing, packaging, transport or holding of such food results, or may be reasonably expected to result, (directly or indirectly) in it or its by-products becoming a component of or otherwise affecting the characteristics of such foods. The term does not include “contaminants” or substances added to food for maintaining or improving nutritional qualities (Codex Alimentarius Commission 1979).
There are gaps and uncertainties in such a definition. The key word in the Codex definition is “intentional.” This excludes substances in which residues are inevitably present that are legitimately used in the production and processing of food. Strictly speaking, these residues are contaminants, but they are variously described as adventitious, indirect, incidental, or unintentional additives and are treated by most regulatory authorities in the same way as substances added for functional purposes to the food itself. They include pesticide residues, processing aids, sanitizers, boiler water additives, and packaging migrants and are quite different in kind, and often in concentration, from industrial contaminants, such as the notorious mercury contamination of the fish in Minimata Bay, Japan, and polychlorinated biphenyls (PCBs). For the purposes of this discussion, then, substances permitted by the Codex definition, together with such nutrients as vitamins and minerals, will be considered to be additives.
Food Additives in History
There is nothing new about the concept of food additives. The ancient Chinese unknowingly used traces of ethylene and propylene from burning paraffin to ripen fruit, although additives were probably used originally simply to preserve food. Smoking is an ancient method of food preservation, usually for meat or fish, which relies partly on drying and partly on the preserving chemicals in the smoke.
Similarly, the resins added to Greek wine act as mild preservatives, and in classical times, the pitch linings of amphorae contributed substances that helped to preserve the wine carried in them. More recently, the practice of burning sulfur in empty wine barrels not only fumigated the barrel but also adventitiously ensured that the wine filling the barrel would be treated with sulfur dioxide, still the preservative of choice in the industry.
It is possible, however, that the first additive deliberately used to preserve foods was salt. Salted foods, especially fish, were known in antiquity. Salt was used lavishly as a preservative; the Romans made a fish sauce, liquamen, in which the fermentation, as well as the keeping quality, was controlled by adding salt. Salt is, however, so familiar and is used so much in such proportions that we now think of it as an ingredient, in contrast to an additive.
The same could be said of sugar, which emerged much later, possibly from India. Salt, however, is a simple inorganic chemical, whereas cane (or beet) sugar is a rather more complex organic molecule. White granulated sugar is a very pure chemical of great value in food preparation, whether in the home or factory. In honey and dried fruits, the sugar present acts as a preservative as does cane sugar in jams—the value of sugar as a flavoring is obvious. Sugar is a functional additive, but today, like salt, it too is thought of as an ingredient. However, saltpeter (sodium nitrate), which has been used from ancient times as a preservative, is not considered an ingredient but is firmly classified as an additive and is subject to continuing scrutiny.
Fermentation was long used as an empirical method of preservation. Alcoholic fermentation is itself a kind of preservation, and alcohol, in the form of brandy, was used in brandied wines as an additive. The production of lactic acid by fermentation, as in cheese, yoghurt, certain cured sausages, and sauerkraut, is another historical example of the formation of a preservative in situ by fermentation. And the acetic acid of vinegar was used by the Romans as a preservative for fruits and vegetables. A modern parallel is the surface treatment of meat with acetic acid to prolong shelf life.
The use of spices as flavorings is very old, as is the Western spice trade with the East. Even if the popularity of spices in Europe was really the result of an efficacy in masking the flavors of salted and tainted meats, the demand for them was established, and it is now known that they also act as mild preservatives. Some 600 years ago, hops were added to beer as a flavoring, which was not at first appreciated; but it was then noted that hopped beer kept better than unhopped ale. Hop resins, too, function as preservatives, but both spices and hops also are today classified as ingredients.
Before the factory production of food, preservation and flavor seem to have been more important than color. Nonetheless, saffron was used as a food color in ancient Egypt, and upper-class Romans had a preference for white bread, which was produced for them by sieving the flour and then adding alum, a practice that persisted until the end of the nineteenth century. Food coloring became popular in medieval times but was confined to the kitchens of the castles and great houses whose chefs used many colors of plant origin. These included indigo, alkanet from the root of borage, sanders from sandalwood, saffron from crocuses, marigold, and turmeric; greens came from the chlorophyll of sage and spinach, and pinks, blues, mauves, and violets from petal extracts.
In the seventeenth century, cochineal (from the dried insect Coccus cacti) and annatto (from the seeds of the shrub Bixa orellana) reached Europe from the New World. The latter was used to color butter and cheese, although in the eighteenth century butter was colored with saffron. In addition, the greening of vegetables by cooking in copper vessels was well known. No food-processing industry existed, however, and additives were confined to the kitchen and to farmhouse and village technology—that is, to butter, cheese, wine, and cider making, and to brewing, baking, and milling. Because there was no food industry, there were no processing aids, sanitizers, boiler water additives, or packaging migrants; nor were there any agricultural chemicals. But there was lead, an outright contaminant that came from the pipes of water systems; from cooking, eating, and drinking utensils; and from ingredients.
The Romans employed lead for collecting and distributing water, and their methods persisted. Even today lead pipes are used for water reticulation in many old houses and buildings in Britain and Europe. In the ancient world, food was cooked and stored in vessels of lead, leaded bronze and brass, and pewter and was served on lead and pewter plates and dishes. The Romans lacked sugar and, for a sweetener, used grape juice concentrated by boiling in lead vessels, because of the extra sweetness derived from the lead salts (Nriagu 1983).
So high was the lead content of the food and drink (especially wine) consumed by the upper-class Romans that lead poisoning has been confidently proposed as one of the major causes of the decline of the Roman Empire (Gilfillan 1965; Nriagu 1983).
Lead acetate (“sugar of lead”) itself, and other lead compounds, were used as sweeteners in wine well into the nineteenth century (Christison 1835; Johnson 1989). In 1767 the disease “Devonshire colic” was identified as lead poisoning and traced to lead fittings on cider presses and lead-lined tanks to hold the apple juice, which, because of the malic acid content, readily picks up lead (Baker 1767, cited in Smith 1986; MAFF 1983). Also during this period, warnings were issued about the danger of the solution of lead from the glazes on earthenware (Drummond and Wilbraham 1957), but as late as the 1870s, lead salts, especially chromate, were being added as colors to confectionery (Dunn 1878).Thus, by 1905, when the Australian state of Victoria introduced food regulations, the first of those regulations included the prohibition of lead in or in contact with food.
The attempts of governments, however, to regulate food additives had a long history. In the late Middle Ages, for example, saffron was used by pastry cooks to simulate eggs, and by the seventeenth century, butter was being colored with annatto. But in 1574 the authorities in the French city of Bourges acted to prohibit egg simulation, and in 1641 Amsterdam prohibited annatto coloring in order to protect May butter, which, because of its color, enjoyed a premium (Meijer 1961; Truhaut and Souverain 1963).
In England in the eighteenth century, claims that chalk and ground bones were added to bread to whiten it were successfully refuted (Drummond and Wilbraham 1957). But there is no doubt that alum was used in this capacity. Calcium carbonate in the form of marble, chalk, or shells was added to beer and cider to counteract acidity; bean flour and isinglass were used as clarifiers; and copperas (iron sulfate) was added to produce a “head” (Drummond and Wilbraham 1957).
With the emergence of factories during the Industrial Revolution, adulteration increased dramatically. Most of this had to do with cheaper substitutes, but some of it involved what would now be called additives: colors, flavors, thickeners, and so forth. In 1820, F. Accum, for example, reported among other things the whitening of bread with alum, the greening of pickles with copper salts, the coloring of Gloucester cheese with red lead, and the flavoring of beer with Cocculus indicus. By midcentury, alum, black lead, Prussian blue, lead chromate, copper carbonate, red lead, vermilion, and copper arsenite were all being used in food and confectionery (Mitchell 1848; Hassall 1855; Campbell 1990). One example of such usage involved spent tea leaves that were “faced” with a mixture of Prussian blue and turmeric to permit their resale as green tea (Cochran 1870).
At least as early as the 1840s, sodium nitrate was employed to preserve butter (Anon. 1843). From the 1830s to the 1870s, attempts were made in Australia to preserve meat with sulfites, phosphoric and lactic acids, acetates, nitrates, and nitrites for shipment to Britain (Farrer 1980). Boric and salicylic acids emerged later in the century as flavored preservatives for sausages, milk, and cordials, and in the United States, this led eventually to the “Poison Squad” of volunteers set up by H. H. Wiley, Chief Food Chemist of the U.S. Department of Agriculture, to test the safety of preservatives then in use.
Similar concerns had surfaced elsewhere. In Canada, a report to a meeting of the British Medical Association in Toronto in 1905 resulted in the Adulteration Act, under which the first list of additives prohibited for use in food was published (Pugsley 1959). In Australia, a report by the Victorian Government Analyst covered (among other things) colors, preservatives, flavors, saccharin, and alum. This led at the end of 1905 to the aforementioned Pure Food Act (Farrer 1980).
In 1856 William Perkin’s accidental discovery of mauveine initiated the dyestuffs industry, which by the beginning of the twentieth century made available a large number of synthetic colors, some 80 of which were being used in food (Noonan and Meggos 1980). Their tinctorial properties were such as to require only very small concentrations to obtain the desired result, and thus they were perceived to be, and were, much safer than the lead, copper, and even arsenic salts that had been used for so long. In 1906, the United States listed 7 colors permitted to be used in foods, and in the interests of commercial rationalization, the number of dyes of “food grade” were soon limited elsewhere by manufacturers. In the period up to World War II, the American list was extended, and lists of colors permitted to be used in foods were adopted by various other countries.
Also in the early years of the twentieth century, borates and salicylates fell into disuse as preservatives and were largely replaced with sulfites and benzoates. For thickening and stabilizing, regular flour was employed (that is, the starch in it), along with corn flour, gelatin, and gums, and the natural lecithin of egg yolk was a common emulsifier. Changes came only after the World War II, when the carcinogenicity of additives and even of ingredients became an issue, and when large numbers of new functional additives became available.
Food Additives in Processing
The appearance, flavor, texture, and keeping quality of foods have always been important, and as noted, additives have long been used to improve them all. By enabling food to be presented in new, attractive, stable, and convenient ways, modern food additives have raised consumers’ expectations to the extent that the demand for the advantages that food additives confer may be said to be sociological rather than technological.
Some may argue that it is the food technologist who has created such a demand, but at best this would be only half true. Colors, flavors, and preservatives have been used for centuries. Gelatin for jelly making, for example, was laboriously prepared in medieval times, and no doubt earlier, from calves’ feet and hartshorn. Chemical aerators for baked goods have been dated from 1842 when Abel Conant obtained a patent for a baking powder. The role of the food technologist has been to simplify the preparation of many of the traditional additives and to offer better, more reliable, and safer alternatives to other older additives, while simultaneously providing and responding to the demand for greater variety, more convenience, and better keeping quality in the food products themselves.
Table VII.9.1 is by no means a complete summary of food additives and the functions they perform, and it is readily apparent that some of them serve more than one purpose. The discussion that follows will concentrate not so much on the additives themselves as on the properties modified by them.
Organoleptic Properties: Color and Flavor
Color has a great deal to do with food selection and appreciation, and thus the argument in favor of the addition of food colors to processed foods is primarily aesthetic. Nonetheless, there are three technological justifications: (1) to intensify natural colors considered by manufacturer and consumer to be too weak; (2) to smooth over color variations in the raw material and thus to ensure standardization of the product in the marketplace; and (3) to replace color lost during processing by heating, chemical reaction (for example, bleaching with sulfur dioxide used as a preservative), or light.
Although all three justifications could be considered extensions of the aesthetic argument, they are part of the fulfillment of consumer expectations and therefore of importance to both manufacturer and consumer. Many natural colors are included in the various permitted lists; some are synthetic but their number is slowly diminishing.
No matter how tempting a food may look, however, if its flavor is found to be unacceptable it will not be bought a second time. Apart from confectionery and beverages (specifically, soft drinks), which are special cases, the arguments for the addition of flavors to foods are the same as those for adding colors. In addition, there is a fourth justification, which is (4) to make flavorful and attractive an otherwise uninteresting formulated product, such as a meat analogue from spun vegetable protein.
Table VII.9.1. Food additives and their functions Source: Farrer (1987).
|Additives||Appearance||Texture||Keeping quality||Flavor||Nutritive value|
|Acidulants, alkalis & buffers||–||–||x||x||–|
|Anticaking & free-running agents||x||x||–||–||–|
|Emulsifiers, gums & stabilizers||x||x||–||–||–|
Natural flavorings have always been used, and by far the largest proportion of food flavors employed today are of natural origin. Because of the chemical complexity of flavors and the low concentrations normally required, it has been difficult to classify and control them, but they are generally recognized as falling into a few categories: (1) aromatic, but natural, raw materials of vegetable or animal origin, such as spices and meat extract; (2) natural flavors that are concentrates of materials in the first category; and (3) natural flavoring substances isolated from them. Then there are (4) flavoring substances that are synthesized or isolated; and finally, (5) artificial flavoring substances that simulate natural flavors but are not found in them. All flavors in the first three categories contain dozens, sometimes hundreds, of separate, naturally present, and identifiable chemical compounds.
Flavorings are sold in solution, and the solvents used, very often alcohol, are subject to the same scrutiny as the flavors themselves. Flavor enhancers are compounds that, apart from salt, have little flavor of their own but have the property of intensifying other flavors. Monosodium glutamate (MSG), possibly the best known of these, was identified early this century from a seaweed preparation known in antiquity for its property of intensifying other flavors.
Some enzymes are very useful in establishing flavor profiles. These substances are of natural origin and are able, among many other things, to split fats, proteins, and carbohydrates. Those associated with flavor development are usually lipases (“fat splitters”) and proteinases (“protein splitters”). They are, perhaps, most obviously active in cheese. Some, in purified form, may be used to develop flavor in other products. Food acids, acidulants, have long been known in the form of vinegar (acetic acid), lemon juice (citric acid), and the juices of other fruits, such as verjuice from grapes and the malic acid of apples.
Their influence on flavor is well known, and many products are flavored with, say, citric or acetic acids.
Nonnutritive sweeteners (as distinct from sugars) are a special group of flavors. The oldest is saccharin, which is hundreds of times sweeter than cane sugar but leaves a slightly bitter aftertaste. More recently, the cyclamates and aspartame were introduced, but the former, probably unfairly, fell under a cloud of suspicion. The latter is now well established, and although these compounds cannot exactly duplicate the taste of sugar, they are valuable in making a useful range of products available to diabetics and people on weight-reduction diets.
Pouring and Slicing: Texture
Many different substances are variously classified as modifiers and conditioners. Between them they contribute to all the qualities of food except nutritive value—especially to appearance and texture. They ensure that emulsions do not break, that salad dressings pour satisfactorily, that baked products do not collapse in crumbs, that crystals of ice, salt, or phosphate, do not form where they are not wanted, and so forth.
Emulsifiers facilitate the dispersion of water and oil in each other to form the emulsions of such things as cake batters, salad dressings, ice cream, processed cheese, and some meat products. Gums of vegetable origin and thickeners and stabilizers, such as gelatin, starches, and modified starches, are then used to stabilize the systems. Humectants maintain the texture of such items as fruitcake and Christmas puddings, by preventing them from drying out, and anticaking agents ensure that salt, milk powders, and the like will run freely when poured.
Aerators have been used traditionally in baked goods to establish the desired texture, in this case, crumb structure, and in so doing have contributed to appearance. Yeasts, as well as yeast food to stimulate fermentation, make up a biological system of aeration, but chemical aerators also are common. They consist of slow-acting acidulants and baking soda and are designed to liberate carbon dioxide slowly enough to enable the desired texture to develop. Enzymes are used to modify texture in many products, and the oldest application may well be the use of rennet to set the curd for cheese making. Other applications are the tenderizing of meat, modification of gluten in dough making, digestion of pectin in fruit products to reduce gelling, and reduction of haze in beer.
Shelf Life: Preservatives and Antioxidants
Food, by its very nature, is perishable because it supports the growth of microorganisms, such as molds, yeasts, and bacteria. As they grow, these organisms can destroy food and render it unfit for human consumption. Yet sometimes, before its unfitness is apparent, such food can be positively dangerous to health. The empirical preservatives of history—salt, sugar, wood smoke, burning sulfur, and the alcohol and acid of fermentation—have been discussed, as have the chemical preservatives that came into use during the nineteenth century.
Modern methods of food processing, especially heat processing and refrigeration, have greatly reduced the need for chemical preservatives, although it is sometimes necessary to include one to protect a product once the container has been opened. This is particularly the case in tropical countries where many do not have home refrigeration. In addition, some modern packaging techniques rely on preservatives. For example, the flexible packaging material used for cheese frequently carries the antimycotic, sorbic acid, to inhibit the growth of the mold spores that are inevitably present on cheese surfaces.
Preservatives are also important in some processes. When meat, for example, is comminuted (as in the making of sausage), heat is generated in it, and the inclusion of a preservative, usually a sulfite, is necessary to stop the growth of microorganisms. Wine making is more difficult without the help of sulfur dioxide to control unwanted microbial growth, and for the same reason this preservative is used frequently in fruit juices.
Nitrates have long been associated with the preservation of meat, and it is now understood that nitrate reduces readily to nitrite, which inhibits the growth of Clostridium botulinum, the most deadly of all food-poisoning organisms. It is also the case that nitrates, via the nitrites, may give rise to nitrosamines that have proved carcinogenic in rats. Yet the benefit of the inhibition of Cl. botulinum outweighs the very low risk associated with nitrosamine formation.
That oils and fats develop rancidity is well known. This is a common flavor defect caused by oxidation that can also produce unacceptable colors and textures. These oxidation defects may be delayed (but not corrected or ultimately prevented) by the addition of antioxidants, and these compounds can, thus, be regarded as a special class of preservatives. In addition, because rancidity is promoted by traces of copper and iron, it is sometimes beneficial to add a sequestrant to an oil, which locks up such trace metals and eliminates their catalytic effect.
Some antioxidants, such as ascorbic acid (vitamin C), the tocopherols (vitamin E), and natural phospholipids (lecithin, for example), occur naturally in fruit and vegetables, whereas others, like the gallates, are synthetic compounds. Antioxidants may be used in oils and fats, as well as in other food products where their use has been shown to prolong shelf life. Also it has been suggested that some antioxidants in food may offer protection against certain forms of cancer of the alimentary tract.
The acidity (or alkalinity) of a biological system is an extremely important property, usually expressed as pH within a range from 1 (very acid) through 7 (neutral) to 14 (very alkaline). Acids, such as the vinegar used in salad dressings, send the pH down, whereas alkalis move it up. If it is necessary to hold the pH steady, a buffer is added. This is a substance that has the ability to “soak up” the acidity or alkalinity. Phosphates are the most common buffers used in food systems. The pH of most phosphates ranges from about 3 (some salad dressings) to about 8. Low pH (high acidity) inhibits microbial growth; conversely, higher pH, either slightly acid or on the alkaline side of neutral, favors such growth, meaning that meats and some cheeses are more vulnerable to microbial spoilage than, say, tomato products. Clearly then, the keeping quality of food products may frequently be improved by lowering the pH.
Vitamins and minerals are added to foods for a number of reasons, the most important being to protect or improve nutritive value. The invention of margarine in 1870 introduced a new product that lacked the vitamins A and D of butter. This deficiency was not, of course, discerned until after the discovery of vitamins early in the twentieth century, and when eventually sources of A and D were commercially available, it became obligatory for the margarine manufacturers to add them to their products. This is a good example of the addition of a nutrient to a substitute (or analogue) in order to match the concentration found in the natural product.
A fine example of the rectifying of processing losses that could otherwise endanger the health of whole communities is found in the addition of B vitamins (especially thiamine) to rice after it is stripped of a vitamin-rich husk in a polishing process intended to improve keeping quality. Similar examples include the addition of calcium to the British national loaf in wartime; the addition of vitamin D to milk; the addition of iodine to salt or to bread for the prevention of goiter; and the addition of fluoride to water for the prevention of dental caries. All are illustrative of government additive programs in the interests of their constituents.
Rather different, however, was the addition of nutrients for purely commercial reasons—an initiative that dated from the late 1940s, when vitamins became freely available as ordinary items of commerce. A rash of advertising claims were made to the effect that the addition of large “unnatural” concentrations of vitamins, and some minerals, made products more “healthy.” As a result of such exagerated claims, some countries now limit the addition of vitamins and minerals to specific products and in specific concentrations.
During the processing of food, it is inevitable that (as in the kitchen) vitamins and minerals will be lost to a greater or lesser extent. The example of polishing rice is a special case, but in both kitchen and factory, losses resulting from leaching and heat are common, which is the reason for the addition of sufficient quantities of vitamins to replace these losses. Similarly, the concentrations of some vitamins will fall during storage, and additions ensure that at the end of the stated shelf life of the product the vitamin activity claimed or expected will still be present. There might also be reason to standardize a product made from variable raw material, so that it contains the level of a vitamin or a mineral that would normally be expected of it.
Additives from the Field
Many chemicals are used in agriculture, horticulture, and animal husbandry, and it is inevitable that traces of them will find their way into foods. Because of this result, some regulatory authorities subject such chemicals to the same close scrutiny as is given to additives proper. Of these substances, the most important are pesticides, which are used directly on food products. Traces large or small, usually depending on the way in which instructions for harvesting are observed, will be found on almost all raw food materials, and regulations governing the concentrations of pesticides permitted in food offered for sale have been introduced throughout the world since the 1950s. It is fortunate that the development of the wide range of chemical pesticides available today coincided quite closely with the discovery and application of modern methods of chemical analysis, which permit the measurement and detection of pesticides in very low concentrations.
Additives from the Factory
Many substances are legitimately used in the food factory to facilitate processing and to clean and sanitize both plant and equipment, and these may be found in foods in minute amounts. For example, traces of boiler water additives to prevent the buildup of scale in steam boilers can be transferred in droplets of water in wet steam. Processing aids that may enter foods include flocculants and clarifying agents, enzymes, lubricants (such as medicinal paraffin on packaging machinery), and talc (on certain types of confectionery), along with quick-release agents in the baking industry. In addition, because cleanliness and the highest hygienic standards are essential, detergents (which sometimes must be quite specialized) and sanitizers used daily in food factories, can also enter foods.
Additives from the Package
The first packages in modern food technology were Nicolas Appert’s glass jars of the 1780s, which were followed by tin cans in 1810.The former contribute little to the food packed in them. But the latter may transfer tin, iron, and (in the past) even lead from the solder used to seal the can, although recent concern over lead in food has resulted in the development of the welded can (to eliminate the soldered side seam). Canned foods inevitably pick up some tin. This metal has not been a cause of significant concern, but the amount that might reach the consumer has been reduced, even though it occasionally imparts a desirable flavor, as with canned asparagus.
The wide use of plastics, both rigid and flexible, in the packaging of food products has focused attention on traces of residual monomers, plasticizers, colors, and so forth that may find their way from the package into the food, especially oily and fatty products. Some of these substances are potentially dangerous, and industry worldwide has collaborated with regulators to develop strict guidelines for plastics that come into contact with foods.
Control of Food Additives
The English “Assize of Bread,” which remained in force from 1266 until the Bread Act of 1822, controlled weight and price but not additives. The French “Livres des Métiers” of 1268 sought to protect both the pocket and the health of the consumer and touched upon additives by forbidding the flavoring of beer. The appointment of German wine inspectors for Swabia and Alsace dates from 1488, and measures were taken at about this time by companies in England, the Netherlands, and France to protect their good names by controlling the misuse of certain additives.
In 1701, the government of Denmark issued an order against food that was tainted or unwholesome or that could cause sickness. This was a vague regulation with only the faintest implication of additive control, but a list of colors permitted for use in food was issued in Denmark in 1836, well before the first dye was synthesized. In 1887 the use of harmful colors in foods was forbidden by the German “Color Act” (Hinton 1960; Uhl and Hansen 1961; Hamann 1963; Truhaut and Souverain 1963).
In England, additive control was inextricably linked with the control of adulteration. Accum’s 1820 treatise dealt primarily with adulteration, and only with modern eyes can it be seen as an indictment of the abuse of additives. Similarly, the search for pure food in the United Kingdom, which has been well documented by I. Paulus (1974), was only incidentally related to additive control. Regulations under the Victoria (Australia) Pure Food Act of 1905 and those flowing from the American Pure Food and Drug Act of 1906 were not primarily directed at additives, although as noted, concern over lead incidentally finding its way into food was a factor. The French, too, early in the twentieth century, accepted the possibility of dangerous metals (lead, zinc, arsenic, antimony) entering the food from utensils or kitchen equipment (Truhaut and Souverain 1963), and up to World War II many countries placed limitations of one kind or another on colors, preservatives, and heavy metals in foodstuffs.
Concern over food additives, first by governments and then by consumers, began to intensify in the 1950s. There were four reasons:
- Results from animal tests in the late 1930s strongly suggested that a so-called coal tar dye used to color butter and margarine was carcinogenic; this finding converged in the late 1940s with a growing awareness of environmental links with some forms of cancer, and a 1952 lecture by A. F. J. Butenandt on the carcinogenicity of some food colors was taken up by the press (Hamann 1963).
- Food technology had emerged during the war as an important new subject of study, and industry was offering a range of substances that could simplify the preparation of many existing products and permit the formulation and manufacture of new ones.
- Analytic chemistry was on the threshold of enormous advances, and the detection and measurement of additives and the like was fast becoming easier.
- There were new needs and, through United Nations agencies, new opportunities for the international regulation of food.
Governments in a number of countries appointed committees and developed mechanisms to study and propose regulations for food additives. In 1956, the United Nations Food and Agriculture and World Health Organizations set up a Joint Expert Committee on Food Additives (JECFA) for the same purpose. JECFA adopted a set of principles as follows:
- Food additives should not be used to disguise faulty processing or handling techniques, nor to deceive the consumer with regard to the nature or quality of the food.
- Special care should be exercised in the use of additives in foods that may form a major part of the diet of some sections of the community, or that may be consumed in especially large quantities at certain seasons.
- The choice of food additives should be related to the prevailing dietary patterns within a community. The availability of essential nutrients and their distribution in the various foods consumed should be taken into account before the true significance of making a further addition of a particular nutrient (e.g., calcium or phosphorus) or of using an additive that may change the pattern of nutrients in a food (e.g., an oxidizing agent) can be assessed.
- The specifications needed for each food additive have been compiled with three main objectives in mind: to identify the substance that has been subjected to biological testing; to ensure that the substance is of the quality required for safe use in food; to reflect and encourage good manufacturing practice (JECFA 1957).
In 1953, Australia had adopted similar principles (Farrer 1990). In Canada, the Adulteration Act of 1884 had included four general principles related to food additives, and in 1906 a report to the Canadian government made six recommendations, which, though directed specifically at preservatives, were the first related to the use of food additives (McGill 1906).The four general principles called for toxicological safety, technological need, labeling, and, where there is no provision for their use, exclusion. In effect, these are the principles that govern the use of food additives today.
Expert committees in many developed countries and the Scientific Committee for Food (SCF) of the European Community (EC) gather and assess information from many sources before deciding whether to recommend a specific additive for use in food and, if so, under what conditions. In some countries the technological need for a given additive in a given product must be demonstrated. But the SCF makes the questionable assumption that a request for permission to use an additive is prima facie evidence of technological need and concerns itself only with toxicological safety. In both cases, if there is any doubt about the toxicological safety of the additive in the way it is to be used, it will not be recommended. JECFA has a key role in establishing toxico-logical safety, and the information it seeks is detailed and stringent. Full details of the substance are required: how it is made, likely impurities, its method and rate of use, what happens to it in food, its effect on nutrients, and the substitute additives available.
Much detailed toxicological and pharmacological information about the additive also is sought: the no-observable-effect level (NOEL) of additives—that is, the concentration in the diet expressed as mg/kg of body weight that may be consumed over several generations without producing any discernible effect; cute and chronic toxicity; the results of studies on carcinogenicity, mutagenicity, and teratogenicity, and of changes induced in cells and the nervous system; and whether the additive triggers or exacerbates an effect caused by another substance or alters the balance between naturally occurring substances. The 1980s saw a heightened awareness of the allergenic properties of some additives, and it is possible that in the future, more questions will be asked about neurotoxicity. The results obtained from all these studies are important, but equally important are the methodologies, which also must be reported.
From all the information generated by these investigations and using a safety factor of, usually, 100, JECFA calculates an Acceptable Daily Intake (ADI). This is “the amount of a chemical which may be ingested daily, even over a lifetime, without appreciable risk to the consumer in the light of all the information available at the time of the evaluation” (JECFA 1957). Without appreciable risk is taken to mean the practical certainty that injury will not result after a lifetime exposure (Vettorazzi 1975). If the data are insufficient to satisfy the committee, a “Temporary ADI” may be adopted, or it may be a case of “No ADI Allocated.” Substances of very low toxicity are classified as “ADI not Specified,” and the designations “Not to be used” and “Decision postponed” speak for themselves. JECFA assessments are very thorough, and its recommendations count for a great deal with both national and international regulatory authorities. They are reflected in the International Standards of Codex Alimentarius, which are of increasing importance in the world trade of food products.
In some countries, permitted additives have been listed for use in all foods, as, for example, substances classified in the United States as GRAS (Generally Recognized as Safe). In others, such as the United Kingdom, the tendency has been to let the courts decide what is “harmful,” although the Public Health Regulations 1925 (Preservatives etc. in Food) limited preservatives to sulfur dioxide, sulfites, benzoic acid, and benzoates, and their use to 20 categories of food (nitrates were excluded from the definition of “preservative”).
The trend now is to limit additives to specified products and limit them up to specified concentrations. These limitations combine the concepts of technological need and toxicological safety-in-use. In addition, former blanket labeling provisions (for example, the general statement “Artificially Colored”) are being replaced by explicit requirements for the naming of each additive, or at least inclusion on the label of identifiable codes, such as the numbering system used in Europe and elsewhere. These requirements make it possible for persons who show idiosyncratic responses to avoid substances that are safe-in-use for the vast majority of people.
Because the evidence relating to substances proposed for use as food additives is freely available all over the world, lists of permitted additives and their concentrations are very similar. Nevertheless, there are differences, most of which reflect likes, prejudices, cultural differences, and politics. In the latter case, the range is from the influence of pressure groups (those of both consumers and industry) to the widespread effect of the American “Delaney Clause.” Enacted by the U.S. Congress in 1958, this clause prohibits the use in food of any substance that has been shown to cause cancer when ingested by humans or any animal.
Ostensibly unchallengeable, this clause has caused untold difficulty in America and in many other countries as well. It takes into account no qualifying circumstance, such as dose levels (that is, amount of substance in a serving), variations in the responses of different animal species, the size of the animal, the frequency of consumption of the substance, and so on. Moreover, in the words of one commentator, “this clause has generated much controversy because of recognition by most scientists that the continued existence of mankind is silent witness to the fact that low levels of carcinogens can be tolerated” (Wodicka 1980). Fortunately, no other country is so legally constrained as the United States. There was recourse to the principle of de minimis non curat lex (“the law is not concerned with trifles”), which enabled some scientific evaluations to be made (Middlekauf 1985), but only for a few years. In 1992 a court decision in the United States ruled that the Delaney Clause meant no levels of carcinogens were permissible (Winter 1993). Because of the extreme sensitivity of modern methods, this definition has created a difficult (some would say, impossible) situation.
Food Additives in Popular Culture
Late-twentieth-century food-additive usage has a foundation of scientific evaluation that is not readily apparent to the casual observer. Newspaper articles, radio and television programs, books, even school teachers, inveigh against food additives as “chemicals added to our food.” Some individuals class as contaminants certain substances that add quality to processed food products, and reject additives without any understanding of their functions. Nor is it generally understood that more fearsome substances occur naturally in foods than are ever added by humans.
Some food manufacturers have sought to profit from public uneasiness by advertising their products as free from all, or at least free from stipulated classes of, additives. One result has been to reinforce many consumers’ uncertainties while creating unjustified suspicion of other products.
For many people, the most damning thing about food additives is that they are “chemicals,” and chemicals are perceived as something to be avoided. Unfortunately, the chemical nature of food and of life itself is generally unappreciated. The body contains thousands of chemicals from the simple, such as water and salt (sodium chloride), to the complex, such as hemoglobin and cholesterol, and all are necessary for life itself. Water, salt, and many others must be supplied in the food, whereas hemoglobin and thousands more such compounds are made by the body as required. In addition, there are substances such as cholesterol, which is both manufactured in vivo and supplied in foods, such as eggs. And then, there is monosodium glutamate (MSG), which is naturally present in some foods, manufactured in the body from others, and also used as an additive.
For generations, cooks have used potassium hydrogen tartrate and sodium hydrogen carbonate. Better known as cream of tartar and baking soda, respectively, both are chemicals and both are food additives. There are many such examples of additives with familiar names; but there are others, known only by intimidating chemical names, that are no less safe. Similarly, many examples could be given of chemical reactions that occur in food during cooking and processing and of others that go on continuously in the body to permit such simple operations as breathing or typing these words.
Late-twentieth-century opponents of food additives cite several concerns. A major one relates to possible long-term and cumulative effects of their consumption, and the further possibility of interactions in vivo of additives with each other, with other food constituents, and with body components. Another concern is that toxicologically innocuous substances may cause nutritional imbalance or the physical obstruction of some biological process. Certainly, none of these possibilities should be unequivocally dismissed, but the detailed and exhaustive testing of substances proposed as food additives is intended to ensure that in the circumstances in which they are eventually permitted to be used, they will be safe; that is, they will be “safe-in-use.”
Early in the sixteenth century, the Renaissance physician Paracelsus wrote that all substances are poisons and it was the right dose that differentiated a poison from a remedy. This truth is the clue to the understanding and acceptance of food additives. It is a statement of what is now called dose-response, of which probably the most familiar modern example is the effect of alcohol. For each person there is a limited number of drinks (“units” of alcohol) that produce no visible response in his or her behavior, but once that limit is passed there is a clearly visible response.
Put another way, given time, it is conceivable that the body can cope with any dose, but some substances can quickly swamp the body’s capability to deal with them. Cyanide is well known as a deadly poison, but marzipan contains cyanide. It is, however, in such a small concentration that the body can deal with it without visible response, and in some countries, cyanide is specifically permitted by regulation to be present in marzipan up to a specified (very low) level. Dose-response, knowingly or not, is considered by everyone who drinks fermented liquids, and it is at the heart of food-additive usage. So, too, is risk-benefit analysis.
Certainly there is risk in food consumption, but the greatest risk is not that of food additives but, rather, that of food poisoning. This is a microbial risk, and it is increasing as people eat out more often and as an increasing number of housewives work and find themselves taking shortcuts in the kitchen. It has been calculated that the risk of food poisoning is 100,000 times greater than any risk from food additives (Truswell et al. 1978).
Nonetheless, the community has the right to expect that food-additive usage is fully explained and is as safe as it can be. And government, industry, and food technologists have the responsibility to see that it is.