Food Additives and Food Toxins

Introduction

• For centuries, food additives have been used to improve and preserve foods.
  • Examples include using salt for preserving meats and fish, herbs and spices to improve flavor, sugar for preserving fruit, and vinegar for pickling vegetables.
• Consumers expect flavorful, nutritious, safe, convenient, colorful, and affordable foods.
• Food additives and processing techniques help deliver foods with these attributes.
• There is a strong consumer desire for clean labels and foods without additives, which presents a conundrum for food chemists.

Key Points

• 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,” including common items like sugar, baking soda, salt, vanilla, yeast, spices, and colors.
• All food additives are carefully regulated by federal authorities and various 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, in addition to intentionally added ingredients.

Food Toxins

• Paracelsus (1500s): “All things are poison, and nothing is without poison; only the dose makes a thing not a poison.” Often condensed to: “The dose makes the poison.”
• Harmful or toxic substances can unintentionally enter the food supply through direct contamination, environmental pollution, processing, or deliberate adulteration for economic benefit.
• Many foods can contain toxic materials; most chemicals have a safe range of use but can be toxic at very high doses.
• Most compounds in food have a dose response: inconsequential at low doses but toxic at high doses. This applies to ingredients ranging from pesticides to common items like salt.
  • The key is to identify the safe level, typically the “no adverse effect level” (NOAEL).

Individual Variation in Toxicity

• The toxicity of some materials varies greatly among individuals.
• There is a distribution of what concentration of a material will affect individuals.
• Variations exist in sensitivity to even the most common food ingredients.
  • For example, some populations are sensitive to salt, while most are unaffected.

Sources of Foodborne Toxins

• Sources include certain seafood, microbial contamination and production of mycotoxins, and natural toxins present in plants, fungi, and seafood.
• The increased use of dietary supplements by consumers also presents sources of natural toxins.
• Many compounds are defined as natural toxins found in the food supply, causing a range of symptoms from gastrointestinal upset to death.
• These materials include toxins produced by the species and contaminants resulting from microbiological activity such as aflatoxins.

Fungal Toxins (Mycotoxins)

• Fungal toxins, also called mycotoxins, are produced by fungi or molds.
• Most interest is concerned with storage fungi, molds that grow on relatively dry cereals and oilseeds, belonging to the genera Aspergillus and Penicillium.
• Aflatoxins, formed by members of the Aspergillus flavus group, are the most common fungal toxins.
  • Discovered in the early 1960s in England due to widespread poisoning of turkeys fed toxic peanut meal.
• Aflatoxins are highly carcinogenic.
  • A dose of 1 mg given to rats for short or long periods can result in liver cancer, and a diet containing 0.1 ppm of aflatoxin produces liver tumors in 50% of male rats.

Aflatoxin Occurrence and Control

• Aflatoxins can occur in many foods but are particularly common in peanuts.
• Roasting of peanuts reduces the level of aflatoxin; for example, roasting for a half hour at 150°C may reduce aflatoxin B1 content by as much as 80%.
• However, aflatoxin may still be carried over into peanut butter.
• Aflatoxins have also been 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.
• The development of aflatoxins depends very much on temperature and moisture conditions.
  • With peanuts, contamination occurs mostly during the drying period.
  • Improper drying and storage are responsible for most contamination; this also applies to rice.
• Optimum conditions for growth of Aspergillus flavus are 25° to 40°C with a relative humidity greater than 85%.

Control Measures for Aflatoxin Production

• Control measures focus on reducing water activity to a point where the fungus is unable to grow and maintaining low water activity during storage.
• A moisture content of 18.0–19.5% 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

• The term food additive means 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 (including any substance intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food; and including any source of radiation intended for any such use),
• If such a substance is not generally recognized, among experts qualified by scientific training and experience to evaluate its safety, as having been adequately shown through scientific procedures (or, in the case of a substance used in food prior to January 1, 1958, through either scientific procedures or experience based on common use in food) to be safe under the condition of its intended use;
• except that such a term does not include pesticides, color additives and substances for which prior sanction or approval was granted.

Definition of Food Additives

• Food additives are chemical masses or mixtures of substances that are not consumed alone as food and are not used as the main component, raw material, or auxiliary material of a food product.
• They are allowed to be added to food products in order to preserve, correct, or prevent undesirable changes in the taste, smell, appearance, structure, and other qualities of the food, and whose residues or derivatives remain in the finished product.

Properties of Food Additives

1. It cannot be used to mask problems in food, but it can be used to prevent possible deterioration and quality losses in food.
2. When added to any food, it is not added as a component of that food, but it becomes a component of that food once it enters the food.
3. It is not a food substance on its own and cannot be consumed on its own.
4. A food additive has no nutritional value on its own.
5. It is not a substance used to increase the nutritional value of food.
6. It is not a contaminant that contaminates food during the production, preparation, processing, handling, packaging, storage, or transportation of food.
7. It 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

Safety Assessment

• When determining the safety of food additives, JECFA applies 9 different toxicity tests on 3 different experimental animals (sometimes on humans, but rarely).
• NOAEL: The highest amount of a substance that no toxic effect is observed in experimental animals despite using it throughout our 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.

Regulation

• It is the responsibility of the manufacturer of any food to ensure that all ingredients used are of food-grade purity and comply with specifications and limitations in all applicable authorizations.
• The overall regulatory status of a food is affected by the regulatory status of each individual food ingredient.
• To determine compliance, consider each authorization to be composed of three parts:
  • The identity of the substance,
  • Specifications including purity and physical properties, and
  • Limitations on the conditions of use.

Functions of Food Additives

• Food additives perform a variety of useful functions in foods.
• Food ingredients that are intentionally introduced into foods to aid in processing, to act as preservatives, or to improve the quality of the food are called intentional additives.
• Food ingredients 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.
• These ingredients also help ensure the availability of flavorful foods.

FDA Definition of Food Additive Utility

• To Maintain or Improve Safety and Freshness: Preservatives slow product spoilage caused by mold, air, bacteria, fungi, or yeast. They also 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. They also prevent cut fresh fruits such as 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. Such 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, while other ingredients help maintain the taste and appeal of foods with reduced fat content.

Food Processing

• 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.
• In many food processing techniques, the use of additives is an integral part of the method, as is 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

Classification According to 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

• Preservatives or antimicrobial agents play an important role in today’s supply of safe and stable foods.
• Increasing demand for convenience foods and a reasonably long shelf life of processed foods make the use of chemical food preservatives imperative.
• Some of the 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, and the assurance of a high initial quality of the food to be preserved.