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Lecture Material - Food Safety Inneke Hantoro FOOD ADDITIVES Direct & Indirect Chemical Residues Definition Any substance added to food during production, processing ... – PowerPoint PPT presentation

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Lecture Material - Food Safety Inneke Hantoro
  • Direct Indirect Chemical Residues

  • Any substance added to food during production,
    processing, treatment, packaging, transportation
    or storage.
  • In legally term, it defined as any substance
    the intended use of which results or may
    reasonably be expected to result directly or
    indirectly in its becoming component or otherwise
    affecting the characteristics of any food
    (FDA/IFIC, 1992).

  • Direct additives are added to a food for a
    specific purpose and are identified on the
    ingredient label of the food.
  • Indirect additives unintentionally become part of
    the food in trace amount due to its handling,
    packaging, etc.
  • Excessive levels of an additive or inclusion of
    an undeclared additive may be directly dangerous
    in some instances.

Migration of Packaging
  • Plastic consists of its polymer, plasticizers,
    antistatic agents, stabilizers and antioxidants,
  • Some components are more likely to migrate into
    foods than others, esp. residual plastic monomers
    and plasticizers.
  • The plastic monomers of most health concern are
    vinyl chloride, and styrene.

  • 1. Vinyl Chloride Monomer (VCM)
  • The monomer of polyvinyl chloride (PVC).
  • It leaches into both water and fats.
  • Typical products that absorb VCM are bottled
    mineral water and cooking oils.
  • Mineral water (stored in PVC bottles) has been
    shown to take up VCM. After 6 months, a
    concentration of 170 mg/l was measured.
  • This may lead to a daily intake of 120 ng per
    person in countries where PVC bottled drinking
    water is used.
  • In cooking oils, higher concentrations have been
    found, 14.8 mg/kg.

  • It also the most available for migration from the
    cling films that are used for all kinds of
  • Vinyl chloride has been identified as a liver
    carcinogen in animal models as well as in humans.
  • Acute intoxication causes depression of the
    central nervous system and hepatic damage.

  • 2. Styrene
  • While paper and board materials may transmit
    taint or odor to a food, plastics have a much
    greater potential to do this.
  • These taints may be residual monomer e.g.
    styrene. This is probably the compound usually
    responsible when consumers detect a 'plastic
    taste' in a food
  • Styrene prefers to leach into fats.
  • Typical sources of styrene deli packaging
    (sausages, ham, smoked beef/ bacon/ fish, etc)
    and yoghurt cups.
  • It is a potent mutagen.

  • Styrene-induced toxic effects include renal and
    hepatic damage, pulmonary edema, and cardiac
    arrhythmia. The oral LD50 in rats is relatively
    low is 5 g/kg.
  • Average concentrations of 27 ppb have been
    measured in high-fat yogurt, 71 ppb in fruit
    yogurt, 20 to 70 ppb in other desserts, 18 to 180
    ppb in meat products and 5 ppb in packed fruit
    and vegetable salads.
  • For styrene, a provisional ADI of 40 ng/kg has
    been calculated.

  • 3. Plasticizers
  • Important plasticizers in PVC plastics are the
    phthalic acid esters di-(2- ethylhexyl) phthalate
    (DEHP) and di-n-butyl phthalate (DBP).
  • The phthalic acid esters DEHP and DBP have low
    acute toxicities.
  • However, liver or lung damage by the leached
    plasticizers has been suggested. DEHP and DBP
    appear to be non-genotoxic carcinogens.
  • Since they are widely distributed in materials
    involved in transportation, construction,
    clothing, medicine, and packaging, the concern
    about their health effects has increased.

  • Different plastics and forms are designed for
    specific product containment situations.
  • Use of this plastic packaging in a manner other
    than that for which it was designed may cause
    significant migration of plastic compounds into
    the food.

Situation that can promote contaminants migration
  • Heating containers (by microwave oven) which are
    designed solely for chilled foods.
  • Overheating heat resistant containers.
  • Coming close to laminating leftovers covered with
    cling wrap in the microwave.
  • Following the instruction on the label /
    packaging is important!

Nitrates, Nitrites, and N-nitroso compounds
  • Nitrates (NO3) and nitrites (NO2) are used to
    preserve meat products, such as bacon, ham, hot
    dogs, and cold cuts.
  • The addition of nitrite can give desirable color
    to meat products (pink) and flavor, retards fat
    oxidation, and prevent bacterial growth
    (especially Clostridium botulinum).
  • Nitrites was intentionally added to meat in the
    16th or 17th century.

1. Nitrites
  • Nitrite inhibits the bacterial production by
    inhibiting certain enzymes within the microbe and
    on its cell membrane.
  • Nitrite weakens the bacterial spores, reducing
    the like-hood of germination.
  • Nitrite is very reactive and can be directly
    toxic or form carcinogenic N-nitroso compounds.
  • It can oxidize blood oxyhemoglobin (ferrous form)
    to methemoglobin (ferric form).

  • Oxyhemoglobin is a good transport for oxygen
    throughout the body, while oxygen cant bind to
    methemoglobin ? unavailable for respiration.
  • Excessive nitrite intake can lead to cyanosis and
  • The average lethal dose of nitrite is approx. 4 g
    as sodium nitrite.
  • The sub-lethal doses of nitrite may lead to
    abnormalities in metabolism of the body.

  • When nitrite is acidified to nitric oxide, it
    provides antimicrobial activity.
  • If it reacts with amines under acidic conditions,
    carcinogenic nitrosamines may be formed.
  • The residual amounts of nitrites in various meat
    products should not exceeded 100 mg/kg, or 50
    mg/kg for dried meat products, and 175 mg/kg for
    cured bacon.
  • ADI for nitrites expressed as sodium nitrites is
    0.1 mg/kg body weight.

2. Nitrates
  • Commonly found in water and vegetables,
    especially those grown with high-nitrate
  • It has low reactivity ? not toxic.
  • However, nitrate becomes a hazard when it is
    reduced to nitrite! Dietary nitrates can be
    converted to nitrites during digestion.
  • Cases of life-threatening methemoglobinemia when
    the patients diet contained too many nitrate
    sources (e.g. drinking water and spinach) within
    a short time span.
  • 5 of ingested nitrates in saliva is reduced to
    nitrite by bacteria.

3. N-nitroso compounds
  • There are 2 types nitrosamines nitrosamides.
  • They are formed when a nitroso group replaces a
    hydrogen attached to a nitrogen ? nitrosation.
  • The formation of these compounds is encouraged at
    high temperature and can be catalyzed directly by
    stomach acid or bacteria.
  • Nitrosamines are generally stable and can be
    quickly distributed through the body, although
    need metabolic activation for mutagenic and
    carcinogenic activity.

  • Nitrosamines are found in cured meat products and
    malt products (beer).
  • Another case nitrosamine in rubber baby bottle
  • Nirosamides are direct mutagen.
  • They can be decomposed at mild alkaline condition
    or destroyed by cooking.
  • The mutagenic/carcinogenic potential of nitroso
    compounds in animal models is well documented,
    but the toxicity to humans is not proven.

  • Exposure to nitroso compound can be minimized as
    contaminants by using ascorbic and erythorbic
    acids in curing solutions, which have synergistic
    effect on nitrite.
  • The level of sodium ascorbate is 550 ppm together
    with sodium nitrite (100-200 ppm) in bacon
    product (USFDA).
  • If sugar and LAB are also added, the amount of
    nitrite used is about 40 ppm.

  • The max limit of nitrosamine allowed in fried
    bacon is 10 ppb (USFDA).
  • Nitrite in smoked fish should be monitored as
    well ? at least 100 ppm in vacuum packed smoked
    fish to prevent botulism, but should also be less
    than 200 ppm to prevent nitrite poisoning.

  • Sulfites (SO3) are used as antioxidants to
    prevent enzymatic browning, inhibit bacterial
    growth (in wine), bleaching agent, dough
    conditioner, to prevent melanosis on shrimp, and
    in the production of some food packaging.
  • They are present in the form of sulfur dioxide,
    sodium sulfite, sodium metabisulfite, sodium

  • Individuals with asthma problem are sensitive to
  • GRAS (Generally Recognized As Safe) since 1959,
    but then they are banned by FDA (1986) after
    reported causing some health problems when they
    used to maintain the color and crispness of the
    salad greens.
  • Sulfites sprayed onto foods produce the most
    rapid allergic reactions.
  • Sulfites can destroy thiamin ? banned by FDA to
    be used in important sources of the vitamin (e.g.
    enriched flour).

  • FDA requires that product labels declare sulfites
    in excess of 10 ppm (detected level).
  • Sulfites are not permitted to be used in meats.
  • Their limit in shrimp is 100 ppm.
  • The major food groups contributing to dietary
    intake of sulphites consist of a wide variety of
    foods and soft drinks (dried fruit 6002000
    mg/kg lime and lemon juice, barley water 350
    mg/kg concentrated grape juice 2000 mg/kg beer
    and cider 20200 mg/kg wines 200260 mg/kg).

  • The ADI for sulphites (expressed as sulphur
    dioxide) is 0.7 mg/kg body weight.
  • Unpackaged food in bulk form should have a sign
    stating that sulfites were used.
  • Case sulfite poisoning in US (1997), canned tuna
    contained sulfites (not declared on the label) ?
    sulfites were identified from one of the
    ingredients the hydrolyzed vegetable protein
    (used as flavor enhancer).

Phenolic Antioxidants
  • They are used to protect fats against oxidation.
  • Butylated hydroxytoluene (BHT) and butylated
    hydroxyanisole (BHA) are radical scavenger.
  • They interfere propagation step during lipid
  • Curiously, these antioxidants can exhibit both
    antitumorigenic and tumorigenic effects, and they
    are known to alter enzyme activity affecting
    detoxification of xenobiotics.

  • BHA and BHT have low acute toxicity.
  • They are categorized as GRAS in FDA.
  • In 1980s BHA was suspected to have carcinogenic
    potential in animals and to be nongenotoxic ?
    should have a threshold dose.
  • BHT metabolism is more complex and slower than
    BHA. It is reported to have toxic effects on
    organ systems.
  • However, BHA and BHT are still permitted to be
    used in food ? 0.02 (200 ppm) of the fat oil
    content of the food product or 50 ppm (combined
    BHA and BHT) if they are used dry low-fat product.

  • An important food additive for prevention of
    bacterial growth, for necessary technical reason,
    or for flavor.
  • The chemical name for salt, sodium chloride,
    reveals that sodium is in fact a component of
    salt. By weight, salt is composed of 40 sodium
    and 60 chloride. One teaspoon of salt weighs 5
    grams and contains about 2,300 mg of sodium.
  • Both sodium and chloride ions are important in
    physiological processes, but excess sodium
    directly cause hypertension (high blood
    pressure), a major risk factor for heart disease,
    stroke and kidney disease.

  • The typical modern consumption of sodium is 10-20
    times the amount needed for physiological
  • Potassium containing table salt substitutes can
    cause hyperkalemia in high dose.
  • FDA limit sodium to 2400 mg daily for a 2000-
    calorie diet.
  • The best way to reduce salt intake read labels
    and make educated choices!

  • Sodium labelling defined by FDA
  • Sodium free or salt free Less than 5 mg per
  • Very low sodium 35 mg or less of sodium per
  • Low sodium 140 mg or less of sodium per serving
  • Low sodium meal 140 mg or less of sodium per 3 ½
  • Reduced or less sodium At least 25 less sodium
    than the regular version
  • Light in sodium 50 less sodium than the regular
  • Unsalted or no salt added No salt added to the
    product during processing

Nonnutritive sweeteners
  • Low calorie sweeteners, such as saccharin,
    aspartame, acesulfame.
  • Saccharin
  • It is 300 times sweeter than sugar.
  • It is not metabolized ? no calories.
  • It comes in the forms of pure saccharin, ammonium
    saccharin, calcium saccharin, and sodium

  • Saccharin has low direct toxicity ? has a
  • It was allowed to be used in beverage additive at
    not more than 12 mg/fluid ounce, not more than 30
    mg per serving as processed food additive.
  • ADI for saccharin is 2.5 mg/kg body weight.
  • But it has been implicated as a potential human
    carcinogenic (since 1981), then it was de-listed
    as a safe food additive.

  • In April 2000, saccharin was de-listed as a
    possible human carcinogen due to the lack of data
    in humans suggesting a carcinogenic hazard.
  • This decision caused a controversy. Another
    source stated that saccharin correlated bladder
  • Saccharin-containing products are still required
    to have warning statement on their labels.

  • Aspartame
  • Approved in 1981 as artificial sweetener.
  • It is 200 times sweeter than sugar and has the
    same number of calories per teaspoonful.
  • Aspartame is a dipeptide consisting of L-aspartic
    acid and the methyl ester of L-phenylalanine.
  • It can be hydrolyzed into aspartic acid,
    phenylalanine and methanol during digestion.
  • Chronic methanol exposure can cause visual

  • Phenylalanine can interfere with amino acid
    transport and lead to nervous system disturbances
    ? only a problem in people with the rare genetic
    disease phenylketonuria (PKU) unable to
    metabolize phenylalanine properly.
  • When aspartame containing product are heated or
    stored for a long period, aspartame can be
    decomposed into diketopiperazine (DKP), a tumor
  • ADI for DKP is 30 mg/kg bw.
  • ADI for aspartame is 50 mg/kg bw.
  • In ready to bake product aspartame is limited to
    0.5 by weight.

  • Stevioside
  • A natural sweetener from Stevia rebuadiana plant.
  • It is 200-300 times sweeter than sugar and have
    no calories.
  • It was used as a common sweetener in Japan
    (herbal teas) during 1980s.
  • It was banned in 1991 because of the lack of
    formal toxicological evaluation proving its
  • It is not allowed in Canada and some EU.
  • Some current studies indicate that steviol, a
    metabolite of stevioside may have toxic effect
  • Ironically, stevia is allowed as a nutritional
    supplement (FDA Import Allert 45-06, 1996).

Color additives
  • FDC color ? safe for foods, drugs and cosmetics.
  • Certified color belong to four classes azo dyes,
    triphenylmethane dyes, xanthene dyes and
    sulfonated indigo dyes.
  • They should be used at less than 300 ppm,
    according to GMP? it is still too high
    considering the tolerances of other chemical

  • Some colorants have been de-listed due to their
    carcinogenic potential, such as
  • - FDC Red No.1 ? hepatocarcinogenic
  • - FDC Red No.2 ? still used in developing
    countries (insufficient toxicological evidence to
    human health)
  • - FDC Red No. 4 ? originally margarine/butter
    colorant, delisted in 1976 due to its toxicity.
  • - FDC Red No. 40 ? allowed in US but not in
    some European countries.
  • - Citrus Red No. 2 ? only allowed for coloring
    orange skins, implicated as animal carcinogen.
  • - FDC Yellow No.3 and No. 4 ? originally used
    as margarine colorants, delisted in 1959 due to

  • Yellows No. 5 (tartrazine) and 6 (sunset yellow)
    are associated with allergic reactions and
    specifically required to be declared on
    ingredient labels.
  • Orange B is permanently listed, but is restricted
    to be used on the surfaces of sausage casings at
    level of no more than 150 ppm.

  • Schmidt, R. H. G. E. Rodrick. (2003). Food
    Safety Handbook. John Wiley Sons Inc. New
  • Wood R., L. Foster, A. Damant P. Key. (2004).
    Analytical Methods for Food Additives. CRC Press.
    Boca Raton.