Food Additives and Food Toxins

Introduction

• For centuries, food additives have been used to improve and preserve foods.
  • Examples:
    • Salt for preserving meats and fish.
    • Herbs and spices to improve flavor.
    • Sugar for preserving fruit.
    • Vinegar for pickling vegetables.
• Consumers expect flavorful, nutritious, safe, convenient, colorful, and affordable foods.
• Food additives and processing techniques help deliver these attributes.
• There's a consumer desire for clean labels and foods without additives.
• Food chemists face challenges regarding the use of additives.
• Thousands of ingredients are approved for use in foods.
• The FDA maintains a list of over 3000 ingredients in its database “Everything Added to Food in the United States”.
  • Many are used at home (e.g., sugar, baking soda, salt, vanilla, yeast, spices, colors).
• All food additives are carefully regulated by federal authorities and international organizations to ensure food safety and accurate labeling.
  • JECFA (Joint FAO/WHO Expert Committee on Food Additives) - 1956.
• Foods can contain toxic materials produced by plants, animals, fungi, or microbial contamination.

Food Toxins

• Paracelsus (1500s): "All things are poison, and nothing is without poison; only the dose makes a thing not a poison.”
  • Condensed: “The dose makes the poison.”
• Harmful substances can enter the food supply unintentionally.
  • Through direct contamination.
  • Through environmental pollution.
  • As a result of processing.
  • Through deliberate adulteration for economic benefit.
• Many foods can contain toxic materials.
• Most chemicals have a safe range of use but are toxic at very high doses.
• Most compounds in food have a dose response: inconsequential at low doses, toxic at higher doses.
  • Examples: pesticides, salt.
• The typical dose response curve is similar for most chemicals or food ingredients.
• The key is to identify the safe level, typically the “no adverse effect level” (NOAEL).
• Toxicity varies greatly among individuals.
• There's a distribution in the concentration of a material that will affect individuals.
• Variations in sensitivity exist even to common food ingredients.
  • Example: Some populations are sensitive to salt.
• Sources of foodborne toxins include certain seafood, microbial contamination, mycotoxins, and natural toxins in plants, fungi, and seafood.
• Increased use of dietary supplements also presents sources of natural toxins.
• Many compounds are defined as natural toxins in the food supply.
  • Cause a range of symptoms from gastrointestinal upset to death.
  • Include toxins produced by the species and contaminants resulting from microbiological activity (e.g., aflatoxins).

Food Toxins: Fungal Toxins (Mycotoxins)

• Fungal toxins, also called mycotoxins, are produced by fungi or molds.
• Most interest is in storage fungi, molds that grow on dry cereals and oilseeds.
  • Common genera: Aspergillus and Penicillium.
• The most common fungal toxins are aflatoxins formed by the Aspergillus flavus group.
• Aflatoxins were discovered due to widespread poisoning of turkeys in England in the early 1960s through toxic peanut meal.
• Aflatoxins are among the most powerful toxins known and are highly carcinogenic.
  • A dose of 1 \, \text{mg} given to rats for short or long periods can cause liver cancer.
  • A diet containing 0.1 \, \text{ppm} of aflatoxin produces liver tumors in 50% of male rats.
• Aflatoxins can occur in many foods, particularly peanuts.
• Roasting peanuts reduces aflatoxin levels.
  • Roasting for a half hour at 150^\circ \text{C} may reduce aflatoxin B1 content by as much as 80%.
• Aflatoxins can be found in cottonseed meal, rice, sweet potatoes, beans, nuts, and wheat.
• Through ingestion of moldy feed by animals, aflatoxins may end up as contaminants in milk and meat.
• Aflatoxin development depends on temperature and moisture conditions.
• With peanuts, contamination occurs mostly during the drying period.
• Improper drying and storage are responsible for most contamination.
• Optimum conditions for growth of Aspergillus flavus are 25^\circ \text{C} to 40^\circ \text{C} with a relative humidity greater than 85%.
• Control measures for aflatoxin production focus on reducing water activity to inhibit fungal growth and maintaining low water activity during storage.
• A moisture content of 18.0\text{%} – 19.5\text{%} in cereal grains is required for growth and toxin production by A. flavus.
• Aflatoxin-contaminated commodities can be detoxified by treatment with ammonia, calcium hydroxide, or a combination of formaldehyde and calcium hydroxide.

Food Additives

• Food additive: any substance the intended use of which results, directly or indirectly, in its becoming a component or affecting the characteristics of any food.
  • Includes substances used in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food.
  • Includes any source of radiation intended for any such use.
  • Excludes pesticides, color additives, and substances with prior sanction or approval.
• Food additives are chemical masses or mixtures of substances that are not consumed alone as food.
• They are not used as the main component, raw material, or auxiliary material of a food product.
• They are added to food products to preserve, correct, or prevent undesirable changes in taste, smell, appearance, structure, and other qualities.
• Their residues or derivatives remain in the finished product.

Properties of Food Additives

1. Cannot be used to mask problems in food but can prevent deterioration and quality losses.
2. When added to any food, it becomes a component of that food.
3. Not a food substance on its own and cannot be consumed on its own.
4. Has no nutritional value on its own.
5. Not a substance used to increase the nutritional value of food.
6. Not a contaminant that contaminates food during production, preparation, processing, handling, packaging, storage, or transportation.
7. Must be homogeneously distributed in the food it is placed in.

Organizations

• WHO (World Health Organization): Birleşmiş Milletler Dünya Sağlık Örgütü.
• FAO (Food and Agriculture Organization): Birleşmiş Milletler Dünya Gıda ve Tarım Örgütü.
• EFSA (The European Food Safety Authority): Avrupa Gıda Güvenliği Otoritesi.
• FDA (Food and Drug Administration): Birleşik Devletler Gıda ve İlaç Dairesi.
• CAC (Codex Alimentarius Commission): Uluslararası Gıda Standartları Komisyon.
• JECFA (The Joint FAO/WHO Expert Committee on Food Additives): Gıda Katkı Maddeleri FAO/WHO Ortak Uzmanlar Komitesi.
• JECFA applies 9 different toxicity tests on 3 different experimental animals to determine the safety of food additives; sometimes, the last test can be on humans (rare).
• NOAEL: The highest amount of a substance that no toxic effect is observed in experimental animals despite using it throughout their lives (mg/kg).
• ADI: The daily consumption amount that does not show any toxic effect in our bodies even if we use a substance every day throughout our lives (daily intake allowed amount).
• LD50: The amount that causes the death of half of the total number of people using a substance.
• GRAS: Generally recognized as safe.
• Manufacturers are responsible for ensuring that all ingredients used are of food-grade purity and comply with specifications and limitations in applicable authorizations.
• The regulatory status of each individual food ingredient affects the overall regulatory status of a food.
• Compliance is determined by considering the identity of the substance, specifications (including purity and physical properties), and limitations on the conditions of use.

Utility of Food Additives

• Perform a variety of useful functions in foods.
• Intentional additives are intentionally introduced into foods to aid in processing, act as preservatives, or improve the quality of the food.
• Food ingredients have been used for many years to preserve, flavor, blend, thicken, and color foods.
• They play an important role in reducing serious nutritional deficiencies among consumers.
• Help ensure the availability of flavorful foods.
• FDA defines the utility of food additives as follows:
  • To Maintain or Improve Safety and Freshness:
    • Preservatives slow product spoilage caused by mold, air, bacteria, fungi, or yeast.
    • Help control contamination that can cause foodborne illness, including life-threatening botulism.
    • Antioxidants prevent fats and oils and the foods containing them from becoming rancid or developing an off-flavor.
    • Prevent cut fresh fruits (e.g., apples) from turning brown when exposed to air.
  • 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, or to enhance the nutritional quality of a food.
    • Fortification and enrichment has helped reduce malnutrition in the U.S. and worldwide.
    • All products containing added nutrients must be appropriately labeled.
  • Improve Taste, Texture, and Appearance:
    • Spices, natural and artificial flavors, and sweeteners are added to enhance the taste of food.
    • Food colors maintain or improve appearance.
    • Emulsifiers, stabilizers, and thickeners give foods the texture and consistency consumers expect.
    • Leavening agents allow baked goods to rise during baking.
    • Some additives help control the acidity and alkalinity of foods.
    • Other ingredients help maintain the taste and appeal of foods with reduced fat content.

Food Processing Method

• The use of food additives is in effect a food processing method because both have the same objective—to preserve the food and/or make it more attractive.
• The use of additives is an integral part of many food processing techniques, such as smoking, heating, and fermenting.
• The use of food additives is strictly regulated by national and international laws.
• The National Academy of Sciences (1973) has listed the purposes of food additives as follows:
  • To improve or maintain nutritional value.
  • To enhance quality.
  • To reduce wastage.
  • To enhance consumer acceptability.
  • To improve keeping quality.
  • To make the food more readily available.
  • To facilitate preparation of the food.

Classification of Food Additives

• In general, food additives are classified in 3 different ways:
  • According to their intended use.
  • According to their functions.
  • According to the E numbering system.

Food Supplements Classification According to Their Purposes

• Additives that extend the shelf life of food without compromising its quality:
  1. Acidity regulators
  2. Antimicrobial agents
  3. Antioxidants
• Additives that improve the sensory properties of food:
  1. Textural structure regulators of food
  2. Visual development enhancers of food
  3. Colorants (dyes)
  4. Flavor enhancers (taste and odor substances)
• Food processing aids, structure enhancing additives:
  1. Starters
  2. Enzymes
  3. pH adjusters
  4. Anti-caking agents
  5. Stabilizers
• Nutritional value regulating additives:
  1. Functional and/or dietary additives
  2. Natural and artificial sweeteners
  3. Enriching additives
• Preservatives or antimicrobial agents play an important role in today’s supply of safe and stable foods.
• Increasing demand for convenience foods and reasonably long shelf life of processed foods make the use of chemical food preservatives imperative.
• Some commonly used preservatives—such as sulfites, nitrate, and salt—have been used for centuries in processed meats and wine.
• The choice of an antimicrobial agent has to be based on:
  • A knowledge of the antimicrobial spectrum of the preservative.
  • The chemical and physical properties of both food and preservative.
  • The conditions of storage and handling.
  • The assurance of a high initial quality of the food to be preserved.