Chemical food preservation

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Overview

The use of chemical substances for preserving foodstuffs began when man learned to protect each harvest until the next harvest, and preserve meat and fish by salting or smoking them. The Egyptians, for example, used in dyes and flavorings to increase the attractiveness of certain food products and Romans have used saltpeter (or potassium nitrate), spices and dyes for the conservation and improvement of appearance of food.

Past 50 years, developments in food science and technological advances have led to the discovery of new food additives useful for food preservation against damage and deterioration caused by chemical reactions (non-enzymatic oxidation, degradation of vitamins and amino acids, etc..), biological (enzymatic oxidation and other degradation enzymatically) and microbiological.

Additives that perform this function of food are classified into two main categories: Conservatives and antioxidants.

Conservatives

Preservatives are substances that limit, slow down or stop the growth of microorganisms (bacteria, yeasts, molds) or present within the food and thus prevent the deterioration of the goods or food poisoning. They are used inter alia in cooked food, wine, cheese, fruit juices and margarines.

The number of E conservatives currently authorized in the European Union ranges from E200 to E297. The following table gives some examples of the preservatives commonly used.

Examples of preservatives commonly used
Number E Substance / Class Examples of foods in which they are used
E 200 - 203 Sorbic acid and sorbates Cheeses, wines, dried fruits, fruit purees, trimmings
E 210 - 213 Benzoic acid and benzoates Pickled vegetables, jams and jellies low in carbohydrates, fruits, semi-preserved fish products, sauces
E 220 - 228 Sulfur dioxide and sulphites Inhibit bacterial growth in the dried fruit, canned fruit and wine. They also have antioxidant properties.
E 235 Natamycin Surface treatment of cheese and sausages
E 249 - 252 Nitrites and nitrates Employees in the preparations of meat (ham, sausages, foie gras, etc..) To prevent the growth of Clostridium botulinum.
E 282 Calcium propionate Prevents growth of mold on bread and cooked foods.

Antioxidants

Antioxidants are molecules that help to protect foods against oxidation reactions that accelerate aging. This may be due to alterations of the oxygen in the air, light, trace metals or certain enzymes. Antioxidants include the category of antioxidants and the sequestrants.

Ascorbic acid (vitamin C), contained in many citrus fruits, is commonly used in kitchens and food production to prevent the oxidation of food (color change of fresh-cut or peeled). Vitamin C and its various salts are also added to protect the soft drinks, jams, milk and sausages.

Tocopherols, which are part of the family of vitamin E, is another example of natural antioxidants. They are found mainly in nuts, sunflower seeds, soybean sprouts and corn and they are most often used to keep vegetable oils, margarine and cocoa products.

Ascorbic acid and tocopherols are antioxidants widely used and needs can not be covered entirely from natural sources, these two compounds are also produced synthetically for some time. It is now possible to copy the molecular structure so perfect that there is no difference in either their structure or their effects. In other words, these substances identical to natural "are essentially identical to their originals.

Artificial antioxidants are also used as antioxidants "natural" and "identical to natural." Belong to the main group of gallates (E 310-312). The gallates are added mainly to vegetable oils and margarine to prevent them from turning rancid and to preserve their flavor.

The following table gives some examples of antioxidants most commonly used.

Examples of antioxidants most commonly used
Number E Substance / Class Examples of foods in which they are used
E 300-302 Ascorbic acid, sodium ascorbate, calcium ascorbate Soft drinks, jams, milk, sausage, maintain the color of fresh-cut or peeled
E 304 Ascorbyl Palmitate Sausages, chicken broth
E 306-309 Tocopherols Oils and fats
E 310-311 Gallates, Octyl gallate Fats and oils for the professional production, oils and fats for frying, seasoning, dehydrated soups, chewinggum
E 320-321 BHA (butyl hydroxyanisole)
BHT (butyl hydroxytoluene
Candies, raisins, cheese, peanut butter, instant soups

Other preservatives of food by chemical

Many other applications are being developed, based on the use of substances occurring naturally (they are more easily accepted by the consumer) in animal and plant organisms, even microorganisms, and with antimicrobial or antioxidant properties. Lysozyme, for example, present in body fluids and to a level of 3.5% in the dried egg white is already the subject of applications: it is considered as an additive (E 1105) it is added during food processing. It lyse vegetative forms of many bacteria gram + but is inactive against Gram-negative bacteria (their outer membrane prevents access of lysozyme to the underlying peptidoglycans which are the substrate of this enzyme). Among the substances with antioxidant and antimicrobial properties used, include a few examples:

  1. of animal origin: the lactoperoxidase (present in milk, colostrum, saliva, ...); the ovotransferrine (in egg), lactoferrin (in milk);
  2. vegetable: phenolic compounds present in many spices, organic acids present in many plants.

Legislation on the use of preservatives and antioxidants

Like all food additives, preservatives and antioxidants are subject to strict regulation, despite their beneficial effects on the body (in the case of vitamins C and E) and the keeping of food.

The legislation, generally requires the use of additives is allowed for the food in question and this without exceeding the maximum limits set. In addition, they must be indicated on the packaging of the product categories (antioxidants, preservatives, dyes, etc..) By name or by code.

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