11.8: Food Additives
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Food additives are substances added to food to preserve flavor or enhance its taste and/or appearance. Some additives have been used for centuries; for example, preserving food by pickling (with vinegar), salting, as with bacon, preserving sweets or using sulfur dioxide as with wines. With the advent of processed foods in the second half of the twentieth century, many more additives have been introduced, of both natural and artificial origin. Please take a look at two of the most common additives, coloring agents and preservatives using the Wikipedia links below. When you see these items listed in the "ingredients" section of a food label, will you be able to recognize them? What are they made from? Are they safe to eat in small amounts? Are they safe to eat in large amounts?
Food coloring, or color additive, is any dye, pigment or substance that imparts color when it is added to food or drink. They come in many forms consisting of liquids, powders, gels, and pastes. Food coloring is used both in commercial food production and in domestic cooking. Food colorants are also used in a variety of non-food applications including cosmetics, pharmaceuticals, home craft projects, and medical devices. Color additives are used in foods for many reasons including:
- To make food more attractive, appealing, appetizing, and informative
- 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
- Allow consumers to identify products on sight, like candy flavors or medicine dosages
In the 20th century, the improvement of chemical analysis and the development of trials to identify the toxic features of substances added to foods led to the replacement of the negative lists by lists of substances allowed to be used for the production and the improvement of foods. This principle is called a positive listing, and almost all recent legislations are based on it. Positive listing implies that substances meant for human consumption have been tested for their safety, and that they have to meet specified purity criteria prior to their approval by the corresponding authorities.
A preservative is a substance or a chemical that is added to products such as food, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined.
Antimicrobial preservatives prevent degradation by bacteria. This method is the most traditional and ancient type of preserving—ancient methods such as pickling and adding honey prevent microorganism growth by modifying the pH level. The most commonly used antimicrobial preservative is lactic acid. Common antimicrobial preservatives are presented in the table. Nitrates and nitrites are also antimicrobial. The detailed mechanism of these chemical compounds range from inhibiting growth of the bacteria to the inhibition of specific enzymes.
|sorbic acid, sodium sorbate and sorbates||common for cheese, wine, baked goods|
|benzoic acid, sodium benzoate and benzoates||used in acidic foods such as jams, salad dressing, juices, pickles, carbonated drinks, soy sauce|
|hydroxybenzoate and derivatives||stable at a broad pH range|
|sulfur dioxide and sulfites||common for fruits|
|nitrite||used in meats to prevent botulism toxin|
|nitrate||used in meats|
|propionic acid and sodium propionate||baked goods|
The oxidation process spoils most food, especially those with a high fat content. Fats quickly turn rancid when exposed to oxygen. Antioxidants prevent or inhibit the oxidation process. The most common antioxidant additives are ascorbic acid (vitamin C) and ascorbates. Thus, antioxidants are commonly added to oils, cheese, and chips. Other antioxidants include the phenol derivatives. These agents suppress the formation of hydroperoxides. Other preservatives include ethanol and methylchloroisothiazolinone.
|ascorbic acid, sodium ascorbate||cheese, chips|
|butylated hydroxytoluene, butylated hydroxyanisole||also used in food packaging|
|gallic acid and sodium gallate||oxygen scavenger|
|sulfur dioxide and sulfites||beverages, wine|
|tocopherols||vitamin E activity|
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