FOOD AND NUTRITIONAL ANALYSIS / Additives 217
Various cleanup techniques can be used to remove system, cleanups can be performed with little or no
these contaminants, but they are time-consuming, operator intervention, requiring only that the final
may remove target compounds, and cannot remove extracts be concentrated.
all interfering compounds. One of the primary class-
See also: Carbohydrates: Dietary Fiber Measured as Non-
es of problem compounds is lipid in food samples.
starch Polysaccharides in Plant Foods. Extraction: Solvent
GPC cleanup is a technique that separates target
Extraction Principles; Solid-Phase Extraction; Solid-Phase
compounds from a sample based on their molecular
Microextraction. Food and Nutritional Analysis: Over-
size. Since lipids are very large molecules compared
view. Sampling: Theory; Practice. Sensory Evaluation.
to the target compounds in these methods, they are
effectively removed from the extract prior to analy-
sis. The packing gel used in GPC cleanup is porous
Further Reading
and is characterized by the range or uniformity of
AOAC International (1995) Official Methods of Analysis,
that pore size. GPC operates on the principle of
16th edn. Gaithersburg, MD: AOAC International.
loading all components in an extract on the gel bed,
Horwitz W (1988) Sampling and preparation of samples
and then selectively removing the components of
for chemical examination. Journal of the Association of
larger molecular size. This procedure provides for the
Official Analytical Chemists 71: 241 245.
efficient separation of typical semivolatile and pesti-
Pomeranz Y and Meloan CE (1994) Food Analysis: Theory
cide components from various higher-molecular
and Practice, 3rd edn, pp. 11 29. New York: Chapman
weight compounds. This also improves method
and Hall.
performance and extends GC column life, leading
Proctor A and Meullenet J-F (1998) Sampling and sample
to more efficient analyses. With autosampling and
preparation. In: Nielsen SS (ed.) Food Analysis, 2nd edn,
automatic fraction collection as part of the GPC pp. 71 82. Gaithersburg, MD: Aspen Publishers.
Additives
M Gallego, University of Córdoba, Córdoba, Spain
methods (which consume more than 70% of the an-
M González, Instituto Canario de Investigaciones
alytical process) and the determinative and disc-
Agrarias, La Laguna, Spain
riminative methodologies for the determination of
additives in foods have gone through remarkable
& 2005, Elsevier Ltd. All Rights Reserved.
changes in the last few years as a consequence of the
spectacular advances in analytical instrumentation.
However, in this regard it has to be pointed out that
these modern methodologies (with sophisticated
Introduction
instrumentation) are uncommon in many food
industries.
Foods naturally provide a series of substances that
maintain the vital processes and normal development
of the body, but sometimes it is desirable to add
General Information about
foreign substances to foods in order to modify some
aspect of its properties; these substances are called Food Additives
food additives. The advantages of food additives are
Definition of Additive
undeniable and so no country prohibits them en-
tirely. Currently, the establishment of international Among the various definitions of food additives that
positive lists and the acceptable daily intake (ADI) can be found in international legislation and accords
instituted by international organizations ensure that is the one adopted by the European Union (EU) in its
these additives, used at a normal dosage, will not European Community Directive 89/107/EEC of the
have toxic effects on the human body. Analytical Council of 21 December 1988: any substance not
methods for the determination of additives have been normally consumed as a food in itself and not nor-
developed so that the stability of these substances mally used as a characteristic ingredient of food
until the food s consumption can be monitored and whether or not it has nutritive value, the intentional
also to ensure that the additives are within the limits addition of which to food for a technological pur-
established by legislation. The sample treatment pose in the manufacture, processing, preparation,
218 FOOD AND NUTRITIONAL ANALYSIS / Additives
treatment, packaging, transport or storage of such Table 1 Comparison between the classifications of food add-
itives established by EU and Codex Alimentarius
food results, or may be reasonably expected to result,
in it or its by-products becoming directly or indi-
Improved EU legislation Codex Alimentarius
rectly a component of such foods. This definition characteristic
emphasizes that additives are substances added in-
Color Color additives Color additives
tentionally to food to produce permanent functional
Color Color stabilizers
effects and that they are generally not considered
Preservation Preservatives Preservatives
Preservation Antioxidants Antioxidants
themselves to be foods.
Texture Emulsifiers Emulsifiers
Another food additive definition is that proposed
Texture Emulsifying salts Emulsifying salts
by the Codex Alimentarius Commission: any sub-
Texture Thickeners Thickeners
stance not normally consumed as a food itself and
Texture Gelling agents Gelling agents
not used as a typical ingredient of the food, whether
Texture Stabilizers Stabilizers
Flavor Flavor enhancers Flavor enhancers
or not it has nutritive value, the intentional addition
Flavor Acids
of which to food for a technological (including
Flavor Acidity regulators Acidity and pH
organoleptic) purpose in the manufacture, process-
regulators
ing, preparation, treatment, packing, packaging,
Texture Anticaking agents Anticaking agents
transport or holding of such food results, or may
Flavor Sweeteners Sweeteners
be reasonably expected to result (directly or indi- Texture Modified starch
Texture Raising agents Raising agents
rectly), in it or its by-products becoming a compo-
Texture Antifoaming agents Antifoaming agents
nent of or otherwise affecting the characteristics of
Texture Foaming agents
such foods. The term does not include contami-
Texture Glazing agents and Lubricants
nants or substances added to food for maintaining
lubricants
Texture Firming agents
or improving nutritional qualities. This definition
Texture Flour treatment Flour treatment
indicates the difference between an additive that is
agents agents
added intentionally and a contaminant (e.g., micro-
Texture Humectants Humectants
organisms and their toxins, heavy metals) whose
Texture Sequestrants
presence in a food is unintentional.
Texture Enzymes
Texture Bulking agents Bulking agents
These two examples illustrate that different food
Texture Propellants and Propellants
additive definitions tend to be very similar because a
packaging gases
general consensus has been reached among the ma-
jority of countries as to what an additive is. It should
also be pointed out that a special statute is normally
reserved for dietetic products, nutritive substances various categories. Table 1 shows a comparison be-
added to food products (e.g., vitamins, amino acids, tween the two different classifications.
minerals, etc.), technological processing aids, and In practical terms, a more general classification
aromas. could be created that includes the additive categories
previously mentioned, separating them by the func-
tions that they fulfill in the foods:
Classification of Food Additives
1. additives that increase the shelf life or stability of a
food,
There are many classification methods for additives:
2. additives that improve sensorial qualities without
alphabetical order, numeration of each substance
altering the nature or quality of the food in such a
within a collection of chemicals, or classification by
way that could deceive the consumer,
chemical function. The most common method is to
group them by functional categories, that is, by an- 3. additives that improve the nutritional value of the
foods, and
ticipated use. This is the method used by the EU,
4. additives that aid in the manufacture, transfor-
which classifies additives in 24 categories, and by the
mation, preparation, treatment, packaging, trans-
Codex Alimentarius Commission, which uses 21
portation, or storage of the foods.
categories. The juxtaposition between the types
of additives classified by the EU and the Codex
Alimentarius Commission is not perfect, given that
Food Additive Regulations
the number of categories is different and some
categories that exist in one do not exist in the oth- Although additives are generally associated with the
er. Furthermore, there is a large amount of multi- modern food industry, in reality they have been used
functional additives that could be classified in for centuries. Preserving food has always been a
FOOD AND NUTRITIONAL ANALYSIS / Additives 219
concern for humans and to achieve this end, our an- those that the FDA or the United States Department
cestors used salt to preserve meats and fish; preserved of Agriculture (USDA) had deemed safe for use in
fruit with sugar; and pickled or canned vegetables foods previous to the 1958 amendment and those on
with vinegar. During the nineteenth century and the the GRAS lists. In 1960, the US Congress approved
beginning of the twentieth century, new chemical the Color Additive Amendments to the FD&C Act,
substances were discovered that could be used to which state that all color additives to be used in
preserve and color foods. In the twentieth century the foods, cosmetics, and drugs (including externally ap-
need to combat commercial fraud and abuse led to plied drugs and cosmetics) must be approved by the
the first regulation of chemical food additives by FDA before being sold on the market. Since 1958,
France in 1912, giving rise to the concept of a po- the FDA and USDA have continued to monitor all
sitive list of chemicals allowed to be added to foods. prior sanctioned and GRAS substances in response to
For the first time there was explicit prohibition to the new scientific information and evidence on the safety
addition of chemicals or colorants, which had not of these substances.
been previously approved by law, to foods. The con-
cept of positive lists of additives has lasted until to- International organizations Every country needs to
day and is still in use in modern international have access to reliable evaluations of the risks asso-
legislation. ciated with the chemical substances used in foods,
but relatively few have the technical capability and
-
Regulations in Europe and in the United States the economic means to do individual evaluations on
Since 1988, the EU, using safety evaluations done by the risks posed by the huge number of existing add-
its Scientific Committee for Food (SCF), has harmo- itives. The work done by the Joint FAO/OMS Expert
nized the national legislation of its Member States Committee on Food Additives (JECFA) and the
through European Community Directive 89/107/ Codex Committee on Food Additives and Contam-
EEC, concerning additives that can be used in prod- inants (CCFAC) is extremely important in this
ucts destined for human consumption. The role of regard. Both committees were jointly created by the
the SCF has grown in importance since the adoption World Health Organization (WHO) and the Food
of directives on sweeteners (Directive 94/35/EC), and Agriculture Organization of the United Nations
colorants (Directive 94/36/EC), and other additives (FAO) and are dedicated to studying additives with
(Directive 95/2/EC) in 1994 and 1995. The commit- the objective of producing international regulations
tee, created in 1974 by the European Commission, for them. The JECFA works as the scientific advisor
has dedicated itself to evaluating the possible risks of to the FAO, the WHO, the member governments of
food additives and elaborating guidelines for their the FAO, and the WHO and the Codex Alimentarius
safe use. Meanwhile, the European Commission has Commission. The JECFA establishes guidelines to
established concrete criteria on the purity of add- evaluate the safety of additives, makes toxicological
itives, the general or specific categories of foods with evaluations, determines the ADI of each of the add-
which additives may be used, and the maximum itives, prepares their purity specifications, and evalu-
amounts that can be added to them. ates the frequency of consumption of foods that
In the United States, the regulation of additives is contain additives. The CCFAC advises the Codex
done by the Food and Drug Administration (FDA). Alimentarius Commission on food additives, conta-
As a response to the widespread use of many sub- minants, and naturally present toxic substances; ex-
stances not approved by the FDA, in 1958 the agency amines the purity characteristics and the identity of
created the GRAS lists (Generally Recognized As the additives; establishes the maximum level of con-
Safe), comprising substances that were unanimously taminants in foods; and advises the Products Com-
recognized as safe. These lists, the US equivalent to mittee of the Codex Alimentarius in which foods an
the positive lists in European legislation, included additive can be used and the maximum amounts that
only substances that had been proven by scientific can be added to them.
practice and evidenced to be innocuous to human
beings. In the same year, the Food Additive Amend- Labeling and identification of food additives In ad-
ment, to the Federal Food, Drug and Cosmetic Act dition to the strict criteria applied to the evaluation
(FD&C Act) was passed, requiring the explicit au- of risk and the obligation of having a demonstrable
thorization of an additive before it could be added to use, the regulations also require that additives appear
a food. It also obligates the manufacturer to prove on the labels of the packaging of the foods and drinks
that the additive is safe in all of the forms in which it that contain them. These labels must explain the
will be used. This amendment excluded two groups function of the additive and its name or assigned
of substances from the additive regulation process: number.
220 FOOD AND NUTRITIONAL ANALYSIS / Additives
The identification of food additives using a expressed in milligrams of additive per kilogram of
number is an alternative to stating the specific name body weight per day.
of the additive, which is normally quite long and has
Legal Procedures for the Authorization of
a complex chemical structure. In 1960, the EU
New Food Additives
assigned conventional numbers to food additives to
better identify them. It was decided that each sub-
The EU has established a legislative structure for the
stance would be identified with a number (of three or
authorization of new additives proposed by either
four digits) preceded by the letter E. It was thought
the EU or any of the individual Member States. This
that the additives could be separated into nine
authorization requires a safety evaluation by the SCF,
categories and that each category would have 100
which evaluates the information provided by the
numbers: the first 100 numbers was assigned to color
manufacturers of the new food additive, including
additives (100 199); the second to preservatives
toxicity data and the function of the new additive. If
(200 299); the third to antioxidants (300 399);
the additive passes the safety standards, the commit-
and the fourth to emulsifiers, thickeners, and gelling
tee establishes its ADI. The European Commission
agents (400 499). The initial letter E indicates that
then develops legislation based on the committee s
the additive has been certified by the SCF as safe for
recommendations and then presents it to the Euro-
use in the entire EU. In the framework of the Codex
pean Council of Ministers and the European Parlia-
Alimentarius, in 1989 the CCFAC created the Inter-
ment. The final result is published in a European
national Numbering System (INS). This numbering
Community Directive that obligates each Member
system was created to reach an international agre-
State to make the necessary changes in their national
ement on the identification number of additives and
legislation to include the new additive. Alternatively,
establish a numerically ordered list of additives that
the manufacturers can ask one of the Member States
included the number of each additive and its tech-
for a provisional national authorization while the EU
nological function. The European Commission and
deliberates on whether or not to legalize the additive.
that of the Codex Alimentarius have agreed to adopt
In this case, a committee of experts from the Member
the same identification numbers, although the INS
State evaluates the request, following procedures
system does not include the E prefix, which is re-
similar to those of the SCF. If the Member State es-
served for the EU.
tablishes an ADI, the additive can be approved for
use in that country for a period of 2 years, while the
authorization request is studied in the EU. If the SCF
Criteria Used to Establish the Maximum Food
authorizes the additive it is incorporated in a Euro-
Additive Dose
pean Community Directive. If the SCF denies the
To establish the maximum food additive dose that
authorization request, the additive must immediately
can be used, international authorities consider two
be banned in all of the Member States. Figure 1
basic criteria: technology and toxicology. On the one
summarizes the legislative procedures required to
hand, they assess the amount of the additive that is
authorize additives in the EU.
technologically required to satisfy the objective need
to include the additive in the food; on the other hand,
Food additive
they evaluate the innocuousness of the additive.
The technologically useful dose of the additive is
Provisional national
EU evaluation
that which accomplishes the desired effect on the
authorization
food. The tests that determine the technologically
useful dose must follow the guidelines established in
Committee of experts
the Good Manufacturing Practice used by the food
SCF
from the Member State
industry.
The ADI is established by international organizat-
European Commission
Council of Ministers
ions like the JECFA and the SCF after completing
toxicological evaluations. The toxicological evaluat-
ion of additives is done using as reference the max-
European European Council National authorization
imum dose that does not have a toxic effect on
Parliament of Ministers for 2 years
animals or the maximum dose that in short- and long-
term toxicological studies has not had any significant
EC directive
toxic effects. The ADI for man is defined as the add-
itive dose that, when consumed daily during a life-
Figure 1 Legislative procedures to authorize additives in
time, does not cause a noticeable risk and is the EU.
FOOD AND NUTRITIONAL ANALYSIS / Additives 221
Table 2 European Community Directives (updated on December 2003)
EC Directive Content
General legislation
Directive 89/107/CEE Additives that can be used in products destined for human consumption
Sweeteners
Directive 94/35/CE Sweeteners
Directive 95/31/CE Criteria on the purity of sweeteners
Color additives
Directive 94/36/CE Color additives
Directive 95/45/CE Criteria on the purity of color additives
Directive 99/75/CE Modification of the Directive 95/45/CE
Directive 2001/50/CE Modification of the Directive 95/45/CE
Food additives other than colors or sweeteners
Directive 95/2/CE On food additives other than colors or sweeteners
Directive 96/85/CE Modification of the Directive 95/2/CE
Directive 98/72/CE Modification of the Directive 95/2/CE
Directive 2001/5/CE Modification of the Directive 95/2/CE
Directive 96/77/CE Criteria on the purity of food additives other than colors or sweeteners
Directive 98/86/CE Modification of the Directive 96/77/CE
Directive 2000/63/CE Modification of the Directive 96/77/CE
Directive 2001/30/CE Modification of the Directive 96/77/CE
In the US, a request to authorize a new food add- Table 3 US additive legislation
itive is presented to the FDA. A petition for an add-
Part Content
itive or a colorant must include data pertaining to the
70 82 Regulation of color additives
toxicity of the additive accompanied by toxicological
170 173 General regulation of food additives
tests on animals and even on humans. To evaluate
174 178 Regulation of indirect food additives
whether an additive should be approved, the agency
180 Regulation of food additives permitted in food or in
first considers the composition and attributes of the
contact with food on an interim basis pending
additional study
substance, the probable amount that will be ingested,
182 186 Regulation of the substances affirmed as generally
the possible long-term effects on consumers and var-
recognized as safe
ious additional safety factors. If the additive is ap-
189 Regulation of the substances prohibited from use in
proved, the FDA publishes regulations that may
human food
include the types of foods in which it can be used, the
maximum quantities that can be added, and how it
should be identified in the food labels.
Analytical Methods for the
Determination of Food Additives
Food Additive Legislation
The development of analytical methods for the de-
European legislation is compiled in European Com-
termination of food additives responds to the need to
munity Directives that are published in the Bulletin
check the stability of the additives during processing
of the EU. European Community Directives affect
and storage or, primarily, to legal requirements such
the entire EU, setting a time limit for their integration
as: (1) establishing whether there are additives
in the legislation of each Member State, after which
present in foods and whether they are permitted,
they are required to be enforced in the entire EU.
(2) determining their concentration to ensure that
Table 2 is a catalog of European Community Di-
they are within the legally established limits, and (3)
rectives, updated in December 2003, that regulate
confirming the absence of illegal additives in foods.
positive lists of additives, standards for the purity of
additives, and the maximum amounts of additives
Sample Pretreatment: Extraction and Cleanup
that can be added to different categories of foods.
The US additive legislation is incorporated in the The pretreatment of foods before additive determi-
Code of Federal Regulations, Title 21, Chapter 1. nation varies greatly depending on the type of sample
The content of the US legislation is organized in (liquid or solid foods, samples with high content of
parts, shown in Table 3. lipids, proteins or carbohydrates) or the analytical
222 FOOD AND NUTRITIONAL ANALYSIS / Additives
technique employed for the determination of the distillation, membrane separation, dialysis and
additive. Often, very simple samples do not require microdialysis, microwave-assisted extraction, solvent
prior treatment or at the most need uncomplicated extraction assisted by ultrasound, solvent microex-
pretreatments, but most foods need to be treated be- traction, solid-phase microextraction, and stir bar
fore the determination of the additive. Frequently, sorptive extraction.
the first step is to use liquid liquid extraction (LLE) It is important to emphasize that specific difficul-
to eliminate interferences. LLE can be simple or re- ties arise when extracting antioxidants and pre-
petitive (with the same solvent and then combining servatives from fatty foods. Most of the permitted
all the extracts). The extractant and the extraction antioxidants and preservatives are fat soluble, so it
method used depend fundamentally on the kind of may first be necessary to extract the fat from the food
sample being analyzed. The extraction can be done and then extract the antioxidants from the fat.
with a single solvent, principally n-hexane, water As a result, the determination of these additives
or acidified water, acetonitrile, dichloromethane, implies the removal of triglycerides; the techniques
ethanol or methanol, diethylic or petroleum ether, most frequently used to remove triglycerides are
acetone, and chloroform, or with a binary or even saponification of the extracts, esterification of
ternary mixture of the solvents, containing a very the extracts in the presence of lipase, and the
polar solvent, like water or methanol, and other less separation of the analytes by preparative liquid
polar solvents. chromatography.
However, other matrix compounds are extracted
together with the analytes, making it necessary to
Determination, Separation, and Detection of
include an extract-cleanup step. The thoroughness of
Food Additives
this step depends on the detection system: if the de-
tector being used is selective enough, an exceedingly For the determination of food additives several an-
thorough cleanup of the extract is not necessary; but alytical methods are used based on spectroscopic,
if the detector is not very selective, this step must electrochemical, and separation techniques, the latter
eliminate as many as possible of the coextracts that with detectors included.
can interfere in the determination.
For the determination of individual additives
Moreover, because the additive concentration in several spectroscopic techniques are normally em-
this extract is not sufficient for the detection of legal ployed: ultraviolet visible spectrophotometry, spec-
limits, it is necessary to preconcentrate the analytes. trofluorimetry, luminescence, and photoacoustic
LLE is commonly used to separate additives from spectrometry. Sometimes, to increase method selec-
their coextracts. Nevertheless, the recent trend is to
tivity, a combination of spectroscopic techniques is
replace LLE with solid-phase extraction (SPE). It is used. Another alternative to determine individual
possible to use SPE as a single cleanup/preconcen- additives are electrochemical techniques: voltamme-
tration step or as an additional step after LLE. The try, polarography, amperometry, and potentiometry.
use of SPE has become popular because of the great
However, additives are normally combined to
variety of polar and nonpolar sorbents and ionic ex- complement and promote their activity; as a result,
change resins that exist. The sorbents most often it is necessary to develop analytical methods for the
used to preconcentrate food additives are: RP-C18, determination of additive mixtures. Although some
silica gel, sorbents with amino groups, XAD-2 poly- spectroscopic and chemical methods are used, it is
meric sorbent, polyamide and wool.
preferable to use separation methods for this pur-
Supercritical fluid extraction is another technique pose. Most analytical methods used to determine
used to extract food additives. Its main advantages food additives are based on chromatographic
are that it saves both time and solvents; the solvent techniques, although several recent papers have
most often employed is carbon dioxide, for its mod- demonstrated the usefulness of electrophoresis
erate critical temperature (311C) and pressure (73 for the analysis of food colors, sweeteners, antioxi-
atm). In addition, carbon dioxide is not inflammable, dants, and/or preservatives. The separation of
toxic, or very expensive. Methanol is sometimes used food colors has received most attention, with a
as a modifier to adjust the dissolution power of this number of articles published on both capillary
fluid. zone electrophoresis and micellar electrokinetic
Quite recently, other extraction techniques have chromatography.
been developed and are being employed for the de- Thin-layer chromatography, in its normal and high
termination of food additives, but are not yet widely resolution forms, is used for the separation and
used. These techniques include countercurrent quantification of additives with minimal sample
chromatography, gel permeation chromatography, manipulation. The most common detection technique
FOOD AND NUTRITIONAL ANALYSIS / Additives 223
is ultraviolet visible spectrophotometry, although Liquid chromatography is the preferred technique
other techniques such as spectrofluorimetry and mass to determine food additives, which in general are
spectrometry are also used. not very volatile and sometimes are thermolabile.
Table 4 Official AOAC methods of analysis applicable to antioxidants
AOAC method Antioxidant Food Analytical technique
948.26 a-Tocopheryl acetate Foods Colorimetry
942.11 Quaternary ammonium compounds Milk Qualitative test
942.13 Quaternary ammonium compounds Foods, beverages Bromophenol blue method
952.09 Propyl gallate Foods Colorimetry
952.10 Quaternary ammonium compounds Milk Optical crystallographic properties of
the Reineckates
954.06 Quaternary ammonium compounds Milk Eosin yellowish method
965.28 Antioxidants Foods Qualitative test
967.21 Ascorbic acid Juices Titrimetry
968.17 Butylated hydroxyanisole, butylated Cereals Gas chromatography
hydroxytoluene
971.30 a-Tocopherol, a-tocopheryl acetate Foods Colorimetry
975.43 a-Tocopherol Foods Polarimetry
983.15 Antioxidants Oils, fats Liquid chromatography
984.26 Ascorbic acid Foods Semiautomated method fluorimetry
Table 5 Official AOAC methods of analysis applicable to preservatives
AOAC method Preservative Food Analytical technique
892.02 Sulfurous acid free Meat Titrimetry
910.02 Benzoic acid Foods Qualitative test
931.08 Formaldehyde Foods Qualitative test
935.34 Benzoic acid Flour Photometry
950.24 Benzoate, caffeine, saccharin Soda beverages Liquid chromatography
953.12 Dehydroacetic acid Cheese Qualitative test
953.13 Dehydroacetic acid Cheese Spectrophotometry
959.09 Boric acid Meat Semiquantitative test
960.27 Preservatives Milk Qualitative test
960.38 Benzoic acid Non-solid foods, beverages Spectrophotometry
961.09 Sulfites Meat Qualitative test
962.16 Sulfurous acid total Foods Modified Monier Williams method
963.19 Benzoic acid Foods Titrimetry
963.20 Sulfurous acid total Dried fruit Colorimetry
964.13 Nitrites Curing preparations Titrimetry
967.15 Benzoic acid Foods Thin-layer chromatography
968.16 Fumaric acid Foods Polarography
969.26 Boric acid Caviar Spectrophotometry
970.33 Boric acid, borates Foods Qualitative test
970.34 Boric acid Foods Titrimetry
971.15 Sorbic acid Cheeses Oxidation method
972.19 Boric acid Foods Atomic absorption spectrometry
974.08 Sorbic acid Wines Spectrophotometry
974.10 Sorbic acid Dairy products Spectrophotometry
975.10 Sorbic acid Wines Colorimetry
975.26 Boric acid Foods Emission spectroscopy
975.30 Salicylic aid Foods, beverages Qualitative test
975.31 Salicylic acid Foods, beverages Colorimetry
975.32 Sulfurous acid Foods Qualitative test
980.17 Preservatives Ground beef Spectrophotometry
983.16 Benzoic acid, sorbic acid Foods Gas chromatography
987.04 Sulfites total Foods Differential pulse polarography
990.28 Sulfites Foods Optimized Monier Williams method
990.29 Sulfites total Foods, beverages Flow injection method spectrophotometry
990.30 Sulfites free Wines Flow injection method spectrophotometry
990.31 Sulfites Foods, beverage Ion exclusion chromatography
993.03 Nitrates Baby foods Spectrophotometry
224 FOOD AND NUTRITIONAL ANALYSIS / Additives
In most of the methods that have been developed, the chromatography, has been done using ultraviolet
stationary phase used for the additive separation is a visible, fluorescence, electrochemical, and mass
polygosyl-bonded silica reversed-phase sorbent with spectrometry detectors.
octadecylsilane functional groups (RP-C18), although Gas chromatography, with or without derivatiza-
other stationary phases such as reverse RP-C30 and tion, is also used to selectively determine individual or
ionic-exchange phases have also been used. The de- mixtures of food additives. The additive separation is
tection of additives, after their separation by liquid done using nonpolar stationary phases consisting
Table 6 Official AOAC methods of analysis applicable to sweeteners
AOAC method Sweetener Food Analytical technique
934.04 Saccharin Nonalcoholic beverages Semiquantitative method
941.10 Saccharin Foods Qualitative test
947.10 Saccharin Foods Sublimation
950.24 Benzoate, caffeine, saccharin Soda beverages Liquid chromatography
957.09 Cyclamate salts Nonalcoholic beverages Sodium nitrite test
957.10 Cyclamate salts Nonalcoholic beverages Gravimetry
957.11 Dulcin Fruits Qualitative test spectrophotometry
969.27 Nonnutritive sweeteners Nonalcoholic beverages Thin-layer chromatography
969.28 Cyclamate salts Canned fruits Colorimetry
973.28 Sorbitol Foods Gas chromatography
973.29 Saccharin Foods Gravimetry
980.18 Saccharin Foods Differential pulse polarography
Table 7 Official AOAC methods of analysis applicable to color additives
AOAC method Color additive Food Analytical technique
900.01 Color additives Milk Qualitative test
920.114 Color additives Cream Qualitative test
920.119 Color additives Butter fat Qualitative test
920.209 Natural color additives Foods Qualitative test
925.28 Color additives Ice cream, frozen desserts Qualitative test
930.17 Artificial color additives Distilled liquors Qualitative test
930.38 Synthetic organic color additives Foods Column chromatography
938.04 Carotenoids Macaroni products Colorimetry
942.19 Synthetic color additives Oils, fats Spectrophotometry
948.07 Caramel Wines Qualitative test
955.18 Natural and artificial organic and Distilled liquors Spectrophotometry
water-soluble color additives
966.21 Oil-soluble color additives Foods Column chromatography
970.65 Riboflavin Foods Fluorimetry
981.15 Riboflavin Foods Flow injection method fluorimetry
985.31 Riboflavin Ready-to-feed milk-based infant Fluorimetry
formula
988.13 FD&C color additives Foods Spectrophotometry thin-layer
chromatography
Table 8 Official AOAC methods of analysis applicable to emulsifying agents
AOAC method Emulsifying agent Food Analytical technique
920.106 Gelatin Milk, milk products Qualitative test
935.61 Gums Salad dressings Qualitative test
945.51 Gelatin Ice cream, frozen desserts Qualitative test
959.06 Alginates Chocolate products Qualitative test
960.33 Gums Ice creams, frozen desserts Infrared spectroscopy
960.34 Alginates Chocolate frozen desserts Qualitative test
963.25 Alginates Food dressings Colorimetry
968.18 Sodium lauryl sulfate Egg white Colorimetry
974.11 Polysorbate 60 Shortening, oils, dressings Gravimetry
991.30 Polydimethylsiloxane Pineapple juice Atomic absorption spectrometry
FOOD AND NUTRITIONAL ANALYSIS / Antioxidants and Preservatives 225
of 100% poly(dimethylsiloxane), intermediate The Association of Official Analytical Chemists
polarity phases consisting of 5% diphenyl 95% (AOAC) publishes reference methods for the analysis
dimethylsiloxane or 50% diphenyl 50% dime- of additives in foods. The following Tables 4 8
thylsiloxane, and polar phases consisting of 100% summarize the AOAC Official Methods of Analysis
poly(ethyleneglycol). The detection of these analytes applicable to antioxidants (Table 4), preserva-
is usually done using a flame ionization detector, tives (Table 5), sweeteners (Table 6), color additives
which is able to detect compounds with CH (Table 7), and emulsifying agents (Table 8).
groups, or universal detectors like a mass spectrome-
See also: Food and Nutritional Analysis: Overview;
try detector.
Antioxidants and Preservatives. Gas Chromatography:
Identification of Food Additives
Overview. Liquid Chromatography: Instrumentation.
Sweeteners.
When analyzing food additives it is frequently nec-
essary to identify the additives that have been deter-
mined quantitatively using the above cited detectors
Further Reading
that, while supplying high sensitivity (essential for
measuring the established legal limits), are not able
Abidi SL (2000) Chromatographic analysis of tocol derived
to identify these compounds. To confirm the ob-
lipid antioxidants. Journal of Chromatography A 881:
tained results two strategies are used: on the one
197 216.
hand, the use of detectors that are able to unmistak- Belitz HD and Grosch W (eds.) (1999) Food Chemistry,
2nd edn. Berlin: Springer.
ably identify the analytes; on the other hand, the use
Boyce MC (2001) Determination of additives in foods by
of two different detectors to compare their responses
capillary electrophoresis. Electrophoresis 22: 1447 1459.
against the same mixture of additives.
Burdock GA (ed.) (1996) Encyclopedia of Food and Color
Mass spectrometry is an excellent tool that can be
Additives. Boca Raton, FL: CRC Press.
used coupled to either a liquid or a gas chro-
Clydesdale FM (ed.) (1996) Food additives: Toxicology,
matograph to confirm the identity of the additives
Regulation and Properties. Boca Raton, FL: CRC Press.
present in foods. A complete mass spectrum of an
Code of Federal Regulations Title 21, Chapter 1, Parts
additive provides structural information that is
70 82, 170 189. Washington, DC: US Government
unique to the additive. Most of the studies that have
Printing Office, 2003; http://www.access.gpo.gov/cgi-bin/
been done use the ionization technique for electronic
cfrassemble.cgi?title ź 200321.
impact to a certain energy (normally 70 eV). Horwitz W (ed.) (2000) Official Methods of Analysis of the
Association of Official Analytical Chemists, 17th edn.
Detection by a diode array detector can be used to
Arlington: AOAC International.
confirm the identity of an additive. This detector is
Karovicová J and Simko P (2000) Determination of syn-
usually coupled with a liquid chromatograph to
thetic phenolic antioxidants in food by high performance
record the ultraviolet visible spectra for each of the
liquid chromatography. Journal of Chromatography A
chromatographic peaks so that they can be compared
882: 271 281.
with the spectra of the pure compounds. Moreover,
Macrae R, Robinson RK, and Sadler MJ (eds.) (1993)
the purity of each of the chromatographic peaks can
Encyclopaedia of Food Science, Food Technology and
be checked.
Nutrition, vols. I and II. San Diego: Academic Press.
The use of two connected detectors, in succession
Pokorny J, Yanishlieva N, and Gordon MH (eds.) (2001)
or in parallel, is widely employed, coupling them to
Antioxidants in Food: Practical Applications. Boca
either a liquid or gas chromatograph. Raton, FL: CRC Press.
Antioxidants and Preservatives
M H Gordon, The University of Reading, Reading, UK
chemical oxidation of the lipids whereas pre-
servatives retard microbiological deterioration. In
& 2005, Elsevier Ltd. All Rights Reserved.
the UK, the permitted antioxidants and preservatives
are listed in the Miscellaneous Food Additives
Introduction
Regulations (1995). Common allowed antioxidants
Antioxidants and preservatives are added to foods to and preservatives are listed in Tables 1 and 2. The
retard their deterioration. Antioxidants retard allowed additives vary from country to country with
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