Food Preservatives Examples

food-preservatives

Humans have been preserving food for generations, with the earliest known evidence of salt being used to preserve meat and shellfish. Traditionally, other techniques such as using sugar to preserve canned foods and pickling vegetables have become common preservation methods. While all of the preceding methods are still applicable today, new chemical preservation technologies are becoming more prevalent. Food preservatives are the chemicals added to delay degradation in food products by inhibiting the growth of bacteria, fungi, and the oxidation of food constituents. This action usually requires the preservatives to be absorbed by the microorganisms and thus alter their chemical structure to allow passage through the microbial cell wall. When it comes to preserving foods, there are two methods: physical and chemical. Drying, refrigerating, and freezing are some of the few examples of physical preservation, whereas chemical preservation involves adding chemical ingredients to food that prevent oxidation, rancidity, bacterial growth, etc. Let’s take a look at a few examples of commonly used food preservatives.

Examples

Sodium Benzoate

Sodium-benzoate

Sodium benzoate is a food preservative that is labeled by the E number E211 in several processed food items available in the market. It is specifically added to prolong the shelf life of acidic food items such as vinegar, cold drinks, fruit juices, yogurt, etc. In chemical terms, Sodium benzoate is salt with the chemical formula {C}_{6}{H}_{5}{COONa}, and it is an odorless crystalline powder produced by reacting benzoic acid with sodium hydroxide. Sodium benzoate acts as a preservative by inhibiting the growth of several microorganisms including moths, fungi, and bacterias. In particular, sodium benzoate gets absorbed into the cell of growing microorganisms and shifts the pH of the intracellular water to make it acidic. This, in turn, decreases the anaerobic fermentation of glucose inside the cell of the microorganism, thereby inhibiting its growth. Apart from food items, sodium benzoate is also used as a preservative in cosmetics and personal care items, such as hair products, baby wipes, toothpaste, and mouthwash. Although sodium benzoate is safe to ingest on its own, it has been connected to several health risks when combined with vitamin C, which has the potential to convert it into the well-known carcinogen benzene.

Salt

SALT

Table salt, otherwise known as Sodium Chloride, is one of the most common preservatives that one can come across in the kitchen. It has been used for ages to both add flavor and to preserve foods such as meats, pickles, salmon, etc. The features that make it a prominently used preservative are its inexpensive and nontoxic nature.  The chemical action by which salt preserves food is known as osmosis. Essentially, adding enough salt to the food items increases the salinity or salt concentration outside the cell wall of the pathogenic microorganisms. To stabilize the salt concentration, enough water moves through the cell wall and makes the microorganism inefficient to survive. Nonetheless, this method is not effective for all microbial growths. For instance, a 20% salt concentration is effective to kill bacterial growth; however, some organisms such as halophilic (salt-loving) bacterias thrive under extreme concentrations of salt.

Nitrogen Gas

Most of us are familiar with a bag of chips filled with nitrogen gas. Nitrogen is an inert gas comprising 79% of the atmosphere, and it can be distilled from ordinary air. The food companies use this distilled nitrogen in their packaging processes to prolong the shelf life and quality of their products. This method is known as nitrogen flushing in technical terms. Bacterias, such as mold and mildew, rely on oxygen for their growth. Nitrogen flushing is the method in which oxygen-rich air is flushed out of the bags and nitrogen gas is immediately filled as a preservative. Unlike oxygen, inert nitrogen does not react and spoils the food. Moreover, Nitrogen also provides cushioning to the chips and prevents them from undergoing any wear and tear during their transit.

Nitrate and Nitrites

hotdogs

In our previous example, we discussed that nitrogen is used to get rid of oxygen to preserve food; however, the compounds of nitrogen and oxygen known as nitrates ({NO}_{3}) and nitrites ({NO}_{2}) are widely used in the food industry as preservatives. Although nitrates and nitrites are compounds that occur naturally in the human body and some foods, manufacturers also add them to processed foods, such as bacon, to preserve them and make them last longer. Nitrite inhibits the growth of Clostridium botulinum, a harmful bacterium, and it may also have antimicrobial properties against other pathogenic microorganisms. Furthermore, nitrite develops the flavor and color of cured meats while also preventing rancidity, off-odors, and off-flavors from developing during storage. The characteristic pink color of preserved meats is also due to nitrite. The most commonly used nitrites and nitrates are sodium and potassium nitrite and sodium and potassium nitrate. These substances have been attributed E numbers E250, E249, E251, and E252 respectively, which can be easily found on the ingredient label of several food items including bacon, ham, sausages, and hot dogs.

Sulfites

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Sulfites are compounds encompassing a variety of food preservatives that essentially contain {SO}_{2}. As a food preservative, sulfur dioxide acts as a broad-spectrum antibacterial, inhibiting bacteria, yeasts, and molds. It is prominently used in winemaking to prevent malolactic fermentation. To slow spoilage and avoid discoloration, these compounds are also widely added to soft drinks, juices, jams, jellies, sausages, and dried or pickled fruits and vegetables. In winemaking, sulfites are a natural by-product of the fermentation process that works as a preservative against certain yeast and bacteria. It plays an important role in preventing oxidization and maintaining a wine’s freshness. Because some grapes have already spilled juice, the grapes aren’t rinsed before crushing, which could dilute the high-quality free-run juice. Since unwashed skins contain bacteria and wild yeast that might impact fermentation in unpredictable ways, some winemakers choose to employ sulfur dioxide before loading them into the crusher/de-stemmer. Sulfur can be added again during racking or whenever the wine is likely to be exposed to oxygen. Because a small fraction of the population may be allergic to sulfur dioxide, producers are required by law to keep SO2 levels in dry wines below 200 parts per million (many wines contain significantly less), and only slightly higher in dessert wines. Despite international standards, winemakers avoid adding sulfur because of its disagreeable odor and impact on wine’s natural development.

Vitamin C (Ascorbic acid)

ASCORBIC ACID

Ascorbic acid is an organic molecule that occurs naturally and has antioxidant effects. It is a white solid that can seem yellowish in contaminated samples. It readily dissolves in water and produces moderately acidic solutions. One kind of vitamin C is ascorbic acid. Plants, particularly citrus fruits, tomatoes, and green vegetables, contain ascorbic acid. Scurvy is caused by a nutrient deficit in the human diet. Ascorbic acid and its sodium, potassium, and calcium salts are commonly used as antioxidant food additives. These compounds are water-soluble and thus cannot protect non-polar fats from oxidation. For this purpose, the fat-soluble esters of ascorbic acid with long-chain fatty acids can be used as food antioxidants. Ascorbic acid is found in nature in many fruits and vegetables and is produced by the kidney of some animals. Humans are not able to produce ascorbic acid and must obtain it from the diet, or else they will develop a deficiency and, in more severe cases, scurvy. Industrially, ascorbic acid is produced through a multistep process involving bacteria that reduce glucose and produce ascorbic acid as a byproduct.

Butylated Hydroxyanisole (BHA)

butylated-hydroxyanisole-in-potato-chips

When it comes to the preservation of food items that contain fats, one of the most common choices of preservatives is Butylated Hydroxyanisole (BHA). It is an antioxidant consisting of a mixture of two isomeric organic compounds, 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole, and it exists as a white waxy solid with a faint characteristic odor at normal room temperature. It was first synthetically manufactured in the late 1940s, and since 1947, it has been added to foods to preserve fats and oils and keep them from becoming rancid. Moreover, it is also used to preserve and prolong the shelf life of food items that are cooked in fats because of its high thermal stability and antioxidant activity in baked food items. The common food items that contain BHA as a preservative include butter, lard, biscuits, beer, sweets, vegetable oils, snacks, glazed fruits, nuts, chewing, and meat products. On the ingredients label of such food items, BHA is denoted by the E number E320. Besides food items, BHA with a slightly different ratio of 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole is commonly used in cosmetics and pharmaceutical products. Nonetheless, the very properties that make BHA an effective food preservative are also implicated to show adverse health effects, and therefore, the use of BHA for preservation is still under review by food associations around the world.

Butylated hydroxytoluene (BHT)

butylated-hydroxytoluene

Butylated hydroxytoluene (BHT) is also a similar food preservative to Butylated Hydroxyanisole (BHA) that is often used to preserve food items that contain fats. Unlike BHA, BHT is also produced naturally by phytoplankton, including the green algae and different types of cyanobacteria. As BHT is also an antioxidant like BHA, its preservative action also includes stopping the rancidity of fats in food items by free-radical scavenging. It’s used to keep the odor, color, and flavor of food. BHT is found in a variety of packaging materials. It’s also used to make shortening, cereals, and other fat-and-oil-based goods. On the ingredients label of such food items, BHA is denoted by the E number E321. Despite its structural similarity to BHA, BHT is not implicated to show any adverse health effects, and it is not expected to be carcinogenic. In fact, several studies are underway concerning the use of BHT in the diagnosis of herpes and AIDS.

Calcium Disodium Ethylenediaminetetraacetate (E385)

Calcium Disodium Ethylenediaminetetraacetate or CaNaEDTA is a salt of EDTA (ethylenediaminetetraacetic acid) that is primarily used for flavoring purposes and food preservation in canned food items. In general, it is represented by the E number E385 on the ingredient label of food items. In technical terms, it is a white powder with a salty flavor and chemical formula {C}_{10}{H}_{14}{CaN}_{2}{Na}_{2}{O}_{8}. It is an antioxidant that works as a chelating agent in food preservation. It combines with free metal ions (such as Zinc, Iron, Copper, Magnesium, Manganese) which are often present in food & beverage, and prevents them from participating in chemical reactions that might cause discoloration and flavor or odor loss. Calcium disodium EDTA promotes flavor retention and reduces discoloration and turbidity in soft drinks. For instance, in beverages containing vitamin C, calcium disodium EDTA prevents the reaction from the interference of uncontrolled metal ions, which will deteriorate colors and reduce the shelf life of vitamin beverages. It can also preserve an antioxidant in vitamins A, B, D & E. Moreover, it is also used as a preservative in the cosmetics and pharmaceutical industries.

Polyphosphates (E452)

Sodium-Phosphates-in-seafood-

Polyphosphates are a class of polymeric compounds in which the structural unit phosphate ({PO}_{4}) is linked together by sharing oxygen atoms. The most commonly used polyphosphates in the food industry for preservation are Sodium polyphosphate (E452(i)), potassium polyphosphate (E452(ii)), sodium calcium polyphosphate (E452(iii)), and calcium polyphosphate (E452(iv)). They’re utilized to increase binding characteristics, limit moisture loss during heating and thawing, and keep items from drying out. This happens, for example, when meat sandwich fillings are cooked at a high temperature or when frozen chicken is reheated and loses a lot of fluid. Polyphosphates also improve the appearance of meat products in the freezer cabinet by reducing rancidity. Polyphosphates also help to improve shelf life by reducing chemical and microbiological degradation.

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