Case Study 1: Aflatoxins

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Case Study 1Aflatoxins

• Aflatoxins are toxic metabolites (mycotoxins)
  produced by certain fungi in/on foods and feeds
• Best known and most intensively researched
  mycotoxins in the world
• Lead to aflatoxicosis in livestock , domestic
  animals and humans throughout the world
• Aflatoxins exert carcinogenic effects in
  susceptible laboratory animals and acute
  toxicological effects in humans

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History

• 1960 lt100,000 turkeys in England died in a few
  months from an apparently new disease that was
  termed "Turkey X disease
• Ducklings and young pheasants were also affected
• All outbreaks were associated with Brazilian
  peanut meal in feeds which was highly toxic to
  poultry and ducklings with symptoms typical of
  Turkey X disease
• The toxin-producing fungus was identified as
  Aspergillus flavus (1961) and the toxin was given
  the name Aflatoxin by virtue of its origin
  (A.flavis--gt Afla).
• Aflatoxins are produced primarily by some strains
  of A. Flavus and by most , if not all , strains
  of A. parasiticus , plus related species, A.
  nomius and A. niger

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Occurence of aflatoxins influenced by several
environmental factors geographic location
(e.g. soil type and microbes) agronomic
practices (rotations, density, etc susceptibilit
y of commodities to fungal invasion during
preharvest , storage, and/or processing periods
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• NOTE
• Absolute safety is never achieved
• Many countries to limit exposure to aflatoxins by
  imposing regulatory limits on commodities
  intended for use as food and feed .

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Some Chemistry

• four major aflatoxins B1 , B2 , G1 , G2 plus
  additional metabolic products which also are
  toxic
• 18 compounds in total

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difuranocoumarins
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Occurrence

• In Raw Agricultural Products
• Aflatoxins often occur in crops in the field
  prior to harvest
• Postharvest contamination can occur when moist
• Aflatoxins are found in milk, cheese, corn,
  peanuts, cottonseed, nuts, almonds, figs, spices
• Commodities with the highest risk of aflatoxin
  contamination are corn, peanuts, and cottonseed.

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Factors

• Fungal growth and aflatoxin contamination are
  the consequence of interactions among the fungus,
  the host and the environment

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Occurrence (contd)

• In Processed Foods
• Corn is of greatest worldwide concern
• grown in climates that are likely to have
  perennial contamination with aflatoxins
• corn is the staple food of many countries
• procedures used to process of corn help to reduce
  contamination of the resulting food product (e.g.
  unstable in processes used to make tortillas with
  alkaline conditions)
• Aflatoxin-contaminated corn and cottonseed meal
  in dairy rations have resulted in aflatoxin M1
  contaminated milk and milk products

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• Aflatoxicosis and Animal Health
• Aflatoxicosis is primarily a hepatic disease and
  causes liver damage, decreased milk and egg
  production, embryo damage
• All aflatoxins have been shown to cause various
  types of cancer in different animal species.

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Aflatoxins and Human Health

• Humans are exposed to aflatoxins by consuming
  foods contaminated with products of fungal growth
  .
• Exposure is difficult to avoid
• Evidence of acute aflatoxicosis in humans has
  been reported from many parts of the world
• The syndrome is characterized by vomiting,
  abdominal pain, pulmonary edema, convulsions,
  coma, and death with cerebral edema and fatty
  involvment of the liver , kidneys , and heart.

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Control and Management of Aflatoxins

• A- Regulatory Control
• Aflatoxins are considered unavoidable
  contaminants of food and feed,
• The action level for human food is 20 ppb total
  aflatoxins, with the exception of milk which has
  an action level of 0.5 ppb for aflatoxin M1.
• The action level for most feeds is also 20 ppb.

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Action Levels for Aflatoxins
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Methods of Analysis for Aflatoxins in Foods and
Feeds
Complex extractions Chromatography Fluorescence
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• B- Detoxification Strategies
• Structural Degradation Following Chemical
  Treatment alkali, acids
• Modification of Toxicity by Dietary Chemicals
• Alteration of Bioavailability by Aflatoxin
  chemisorbents A new approach to the
  detoxification of aflatoxins is the addition of
  inorganic sorbent materials, known as
  chemisorbents, such as hydrated sodium calcium
  aluminosilicate (HSCAS) to the diet of animals.

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Properties / Stability

• Heat
• Aflatoxins in dry state are very stable to heat
  up to the melting point. However, in the presence
  of moisture and at elevated temperatures there is
  destruction of aflatoxin over a period of time.
• Alkalis In alkali solution hydrolysis occurs
  which may be reversible.
• Acids In acids, aflatoxin B1 and G1 are
  converted in to aflatoxin B2A and G2A
• Oxidizing agentsMany oxidizing agents, such as
  sodium hypochlorite, chlorine, hydrogen peroxide,
  and ozone react with aflatoxin

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Economic Impact of Aflatoxins

• Economic impact of aflatoxins derive directly
  from crop and livestock losses
• The Food and Agriculture Organization (FAO)
  estimates that 25 of the world's food crops are
  affected by mycotoxins, of which the most
  notorious are aflatoxins.
• Long term cancer risks unknown

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• Large batches of milk were dumped (US) because of
  their content of aflatoxin M1 that exceeds the
  FDA action Level of 0.5 ppb for milk.

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Food Additives

• A food additive is any substance added to food
• "any substance the intended use of which results
  or may reasonably be expected to result --
  directly or indirectly -- in its becoming a
  component or otherwise affecting the
  characteristics of any food."
• Includes any substance used in the production,
  processing, treatment, packaging, transportation
  or storage of food
• This definition excludes ingredients whose use is
  generally recognized as safe (government approval
  is not needed)
• Direct food additives are those that are added to
  a food for a specific purpose in that food. E.g.
  xanthan gum -- used in salad dressings, chocolate
  milk, bakery fillings, puddings and other foods
  to add texture -- is a direct additive.
• Indirect food additives are those that become
  part of the food in trace amounts due to its
  packaging, storage or other handling.

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Food Additives

• Food including additives have been used for many
  years to preserve, flavor, blend, thicken and
  color foods, and have played an important role in
  reducing serious nutritional deficiencies among
  consumers.

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Why are food additives and colors used in foods?

• To Maintain or Improve Safety and Freshness
• Preservatives slow product spoilage caused by
  mold, air, bacteria, fungi or yeast.
• To Improve or Maintain Nutritional Value
• Vitamins and minerals (and fiber) are added to
  many foods to make up for those lacking in a
  person's diet or lost in processing
• Improve Taste, Texture and Appearance
• Spices, natural and artificial flavors,
  sweeteners food colors, emulsifiers, stabilizers,
  thickeners, leavening agents, pH control, fat
  replacers

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Food Additives (Improvers)

• ANTIOXIDANTS
• retard oxidation of unsaturated fats and oils,
  colorings, and flavorings
• CHELATING AGENTS
• trap trace amounts of metal atoms that would
  otherwise cause food to discolor or go rancid.
• EMULSIFIERS
• keep oil and water mixed together.
• FLAVOR ENHANCERS
• have little or no flavor of their own, but
  accentuate the natural flavor of foods
• THICKENING AGENTS
• are natural or chemically modified carbohydrates
  that absorb some of the water that is present in
  food, thereby making the food thicker
• COLORANTS

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• A color additive is any dye, pigment or substance
  which when added or applied to a food is capable
  (alone or through reactions with other
  substances) of imparting color.
• Color additives are used in foods for many
  reasons
• 1) to offset color loss due to exposure to light,
  air, temperature extremes, moisture and storage
  conditions
• 2) to correct natural variations in color
• 3) to enhance colors that occur naturally
• 4) to provide color to colorless and "fun" foods.
  (e.g. brown colas yellow margarin, green mint ice
  cream)

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Types of Food Ingredientsand What They Do -
Summary Examples

• Flavors and Spices
• Add specific flavors (natural and synthetic)
• E.g. Pudding and pie fillings, gelatin dessert
  mixes, cake mixes, salad dressings, candies
• Preservatives
• Prevent food spoilage from bacteria, molds,
  fungi, or yeast (antimicrobials)
• slow or prevent changes in color, flavor, or
  texture and delay rancidity (antioxidants)
• maintain freshnessFruit sauces and jellies,
  beverages, baked goods, cured meats, oils and
  margarines, cereals, dressings, snack foods,
  fruits and vegetables
• Ascorbic acid, citric acid, sodium benzoate,
  calcium propionate, sodium erythorbate, sodium
  nitrite, calcium sorbate, potassium sorbate, BHA,
  BHT, EDTA, tocopherols (Vitamin E)

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• Emulsifiers
• keep ingredients dispersed, and to help products
  dissolve more easily
• Salad dressings, peanut butter, chocolate,
  margarine, frozen dessertsSoy lecithin, mono- and
  diglycerides, egg yolks, polysorbates, sorbitan
  monostearate
• Sweeteners
• Add sweetness with or without the extra
  caloriesBeverages, baked goods, confections,
  table-top sugar, substitutes, many processed
  foodsSucrose (sugar), glucose, fructose,
  sorbitol, mannitol, corn syrup, high fructose
  corn syrup, saccharin, aspartame, sucralose,
  acesulfame potassium (acesulfame-K), neotame

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• Stabilizers and Thickeners
• Binders, Texturizers
• Produce uniform texture, improve "mouth-feel
• Frozen desserts, dairy products, cakes, pudding
  and gelatin mixes, dressings, jams and jellies,
  sauces
• Gelatin, pectin, guar gum, carrageenan, xanthan
  gum, whey
• pH Control Agents and acidulants
• Control acidity and alkalinity,
• prevent spoilageBeverages, frozen desserts,
  chocolate, low acid canned foods, baking powder
• Lactic acid, citric acid, ammonium hydroxide,
  sodium carbonate

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• Color Additives
• Offset color loss due to exposure to light, air,
  temperature extremes, moisture and storage
  conditions correct natural variations in color
  enhance colors that occur naturally
• provide color to colorless and "fun" foods Many
  processed foods, (candies, snack foods margarine,
  cheese, soft drinks, jams/jellies, gelatins,
  pudding and pie fillings) use FDC Blue Nos. 1
  and 2, FDC Green No. 3, FDC Red Nos. 3 and 40,
  FDC Yellow Nos. 5 and 6, Orange B, Citrus Red
  No. 2, annatto extract, beta-carotene, grape skin
  extract, cochineal extract or carmine, paprika
  oleoresin, caramel color, fruit and vegetable
  juices, saffron
• Anti-caking agents
• Keep powdered foods free-flowing, prevent
  moisture absorption
• Salt, baking powder, confectioner's sugar
• Calcium silicate, iron ammonium citrate, silicon
  dioxide

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• Humectants
• Retain moisture
• Shredded coconut, marshmallows, soft candies,
  confections
• Glycerin, sorbitol
• Yeast Nutrients
• Promote growth of yeast
• Breads and other baked goods
• Calcium sulfate, ammonium phosphate
• Dough Strengtheners and Conditioners
• Produce more stable dough
• Breads and other baked goods
• Ammonium sulfate, azodicarbonamide, L-cysteine

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• Leavening Agents
• Promote rising of baked goods
• Baking soda, monocalcium phosphate, calcium
  carbonate
• SAPP

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• Firming Agents
• Maintain crispness and firmness
• Processed fruits and vegetables
• Calcium chloride, calcium lactate
• Enzyme Preparations
• Modify proteins, polysaccharides and fats
• Cheese, dairy products, meat
• Enzymes, lactase, papain, rennet, chymosin

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• Gases
• Serve as propellant, aerate, or create
  carbonation
• Oil cooking spray, whipped cream, carbonated
  beverages
• Carbon dioxide, nitrous oxide