HOME

TheInfoList



OR:

A humectant is a
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
(water-absorbing) substance used to keep things moist. They are used in many products, including food, cosmetics, medicines and pesticides. When used as a
food additive Food additives are substances added to food to preserve Taste, flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), sal ...
, a humectant has the effect of keeping moisture in the food. Humectants are sometimes used as a component of antistatic coatings for
plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adapta ...
s. A humectant attracts and retains the moisture in the air nearby via absorption, drawing the water vapor into or beneath the organism's or object's surface. This is the opposite use of a hygroscopic material where it is used as a desiccant used to draw moisture away. In pharmaceuticals and cosmetics, humectants can be used in
topical A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes ...
dosage forms to increase the solubility of a chemical compound's active ingredients, increasing the active ingredients' ability to penetrate skin, or its activity time. This hydrating property can also be needed to counteract a dehydrating active ingredient (e.g.,
soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are us ...
s, corticoids, and some
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
s), which is why humectants are common ingredients in a wide range of cosmetic and personal care products that make moisturization claims (e.g., hair conditioners, body lotions, face or body cleansers, lip balms, and eye creams).


Chemistry

A humectant is often a molecule with several
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...
groups, most often
hydroxyl group In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
s; however,
amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent ...
s and carboxyl groups, sometimes
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
ified, can be encountered as well (its affinity to form
hydrogen bond In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a l ...
s with molecules of water is the crucial trait).


Examples

Examples of some humectants include: *
Propylene glycol Propylene glycol ( IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. Containing two alcohol groups, it is classed as a diol. It ...
, hexylene glycol, and butylene glycol *
Aloe vera ''Aloe vera'' () is a succulent plant species of the genus '' Aloe''. It is widely distributed, and is considered an invasive species in many world regions. An evergreen perennial, it originates from the Arabian Peninsula, but grows wild in t ...
gel * Alpha hydroxy acids such as
lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
* Egg yolk and
egg white Egg white is the clear liquid (also called the albumen or the glair/glaire) contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms ar ...
* Glyceryl triacetate *
Honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
* Lithium chloride *
Molasses Molasses () is a viscous substance resulting from refining sugarcane or sugar beets into sugar. Molasses varies in the amount of sugar, method of extraction and age of the plant. Sugarcane molasses is primarily used to sweeten and flavour foods ...
* Polymeric polyols such as polydextrose * Quillaia * Sodium hexametaphosphate E452i * Sugar alcohols (sugar polyols) such as
glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
,
sorbitol Sorbitol (), less commonly known as glucitol (), is a sugar alcohol with a sweet taste which the human body metabolizes slowly. It can be obtained by reduction of glucose, which changes the converted aldehyde group (−CHO) to a primary alcoho ...
, xylitol, maltitol *
Urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important ...
* Castor oil


Uses

A humectant is a substance that is used to keep products moisturized and affects the preservation of items, which can be used in cosmetic products, food and tobacco. A humectant-rich formulation contains simple alcoholic sugar that can increase skin hydration and helps to remove and reduce thickness of skin.


Food additives

Some common humectants used in food are
honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
and glucose syrup both for their water absorption and sweet flavor. Glucose syrup also helps to retain the shape of the product better than other alternatives, for a longer period of time. In addition, some humectants are recognized in different countries as good food additives because of the increase in nutritional value that they provide, such as sodium hexametaphosphate. In order to gauge a compound's humectancy, scientists will put it through a series of tests, often involving water absorption. In tests involving toothpaste, the process is also coupled with a sweetness test and a crystallization test. When humectancy is being assessed in different products, testers will compare the results to other humectants that are already used in those products, in order to evaluate efficiency. Some of these humectants are seen in non-ionic polyols like
sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refine ...
, glycerin or
glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
and its triester ( triacetin). These humectant food additives are used for the purpose of controlling
viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...
and texture. Humectants also add bulk, retain moisture, reduce water activity, and improve softness. A main advantage of humectant food additives is that, since they are non-ionic, they are not expected to influence any variation of the pH aqueous systems. Glycerol or glycerin humectants undergo a pretreatment process using saponification, bleaching, ion exchange exclusion, both cationic and ionic ion exchanges, vacuum flash evaporation, thin film distillation, and heating to produce a 100% pure glycerol. Humectants are used in stabilization of food products and lengthening shelf life through food and moisture control. The available moisture determines
microbial A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
activity, physical properties, sensory properties and the rate of chemical changes, that if not controlled, are the cause of reduced shelf life. Examples are dry
cereal A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food ...
with semi-moist raisins,
ice cream Ice cream is a sweetened frozen food typically eaten as a snack or dessert. It may be made from milk or cream and is flavoured with a sweetener, either sugar or an alternative, and a spice, such as cocoa or vanilla, or with fruit such as ...
in a cone,
chocolate Chocolate is a food made from roasted and ground cacao seed kernels that is available as a liquid, solid, or paste, either on its own or as a flavoring agent in other foods. Cacao has been consumed in some form since at least the Olmec ci ...
,
hard candy A hard candy (American English), or boiled sweet (British English), is a sugar candy prepared from one or more sugar-based syrups that is heated to a temperature of 160 °C (320 °F) to make candy. Among the many hard candy varietie ...
with liquid centers and
cheese Cheese is a dairy product produced in wide ranges of flavors, textures, and forms by coagulation of the milk protein casein. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During productio ...
. Humectants are used to stabilize the moisture content of foodstuffs and are incorporated as food additives. Humectants are also used in military technology for the use of
MRE A Meal, Ready-to-Eat (MRE) is a self-contained, individual field ration in lightweight packaging purchased by the United States Department of Defense for its service members for use in combat or field conditions where other food is not availa ...
s and other military rations. A number of food items always need to be moist. The use of humectants reduces the available water, thus reducing bacterial activity. They are used for safety issues, for quality, and to have a longer shelf-life in food products. An example of where humectants are used to keep food moist is in products like
toothpaste Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, ...
as well as certain kinds of
cookies A cookie is a baked or cooked snack or dessert that is typically small, flat and sweet. It usually contains flour, sugar, egg, and some type of oil, fat, or butter. It may include other ingredients such as raisins, oats, chocolate chi ...
. Regional kinds of cookies often use humectants as a binding agent in order to keep moisture locked into the center of the cookie rather than have it evaporate out. Humectants are favored in food products because of their ability to keep consumable goods moist and increase shelf-life.


Cosmetics

Humectants are frequently used in cosmetics as a way of increasing and maintaining moisture in the skin and hair, in products including shampoo, conditioner, frizz serum, lotions, creams, lip treatments, cleansers, after-sun lotion, and some soaps or body lotions. As hygroscopic moisturizers, humectants work by attracting water to the upper layer of the skin (stratum corneum). All humectants have common hydroxyl groups which allow them to participate in hydrogen bonding and attract water. This process attracts moisture from the outer layer of the skin or, in high humidity, from the atmosphere. The moisture is then trapped against the
epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rel ...
or the shaft of the hair, depending on where the humectant is applied. Various humectants have different ways of behaving because they differ in water binding capacity at different humidities. Humectants used in cosmetics include triethylene glycol, tripropylene glycol,
propylene glycol Propylene glycol ( IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. Containing two alcohol groups, it is classed as a diol. It ...
, and PPGs. Other popular humectants in cosmetics include glycerin,
sorbitol Sorbitol (), less commonly known as glucitol (), is a sugar alcohol with a sweet taste which the human body metabolizes slowly. It can be obtained by reduction of glucose, which changes the converted aldehyde group (−CHO) to a primary alcoho ...
(sugar alcohol), hexylene and butylene glycol, urea, and collagen. Glycerin is one of the most popular humectants used because it produces the desired result fairly frequently and is low in cost. A category of humectants called nanolipidgels allow skin to retain moisture, but also possess antifungal properties. Scientists are also working to discover different types of humectants; a study published in 2011 concluded that extracts from wine cakes have the potential to be used as a humectant in cosmetics. Humectants have been added to skin moisturizing products to treat xerosis. Some moisturizers tend to weaken the skin barrier function, but studies on xerosis have proven that moisturizers containing humectants increase desired moisturizing effects on the affected area without damage to the skin barrier function. In this xerosis treatments study, some "smarting and stinging" was also reported from the use of humectant-rich treatment products. When the humectant glycerol was added to soaps for the cleansing of wounds, similar effects were found. There was an increase in moisture in the areas that the soap was applied, however, "further consideration of conditioning the use of glycerol to improve the absorption of exudates from wounds for an advanced wound healing is needed." The healing properties of humectants are therefore uncertain. Humectants are also added to toothpaste (dentifrice) to stop the product drying out and cracking in the tube. Sorbitol is commonly used as this also contributes a sweet flavour to the toothpaste without contributing to tooth decay.


Tobacco products

Humectants are used in the manufacturing of some
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
products, such as
cigarettes A cigarette is a narrow cylinder containing a combustible material, typically tobacco, that is rolled into thin paper for smoking. The cigarette is ignited at one end, causing it to smolder; the resulting smoke is orally inhaled via the opp ...
, e-cigarettes, and self-rolled tobacco. They are used to control and maintain the moisture content of the cut tobacco filler and add flavor. Humectants are vital to the creation of cigarettes. In an examination of waterpipe smoking, researchers worked to identify substances such as
formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...
,
acetaldehyde Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the ...
, and
acrolein Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is a colorless liquid with a piercing, acrid smell. The smell of burnt fat (as when cooking oil is heated to its smoke point) is caused by glycerol in the burning fat ...
in the smoke of a waterpipe, discovering that the value of formaldehyde detected in one smoking session was five times higher than that of a regular cigarette. This data demonstrated that increasing amounts of humectants in the unburned tobacco lowered the temperature in the waterpipe head during smoking, so that considerable amounts of toxic substances were present. Further, e-cigarettes produce aerosol by heating a humectant containing nicotine without burning tobacco. Those "vaping" then inhale the aerosol and receive nicotine. The main health concern regarding e-cigarettes is that their production is not regulated, and there is immense uncertainty of quality control during manufacturing. Self-rolled tobacco contains more humectants, which are added to tobacco to make it taste better and keep from drying out. As the humectants burn, they unleash chemicals such as acrolein. Humectants are found in most cigarettes and are considered one of the most dangerous chemicals found in tobacco. However, there have been conflicting claims about the degree to which these products warrant a health concern. In a literary study of e-cigarette health risks, 388 different symptoms were reported; mouth and throat concerns generated more negative symptoms than any other group. There are not enough studies or sufficient evidence to suggest that products, particularly the contaminants of the aerosol in e-cigarettes, produce health risks at a concerning level. More research is currently being conducted to find the true dangers of the use of humectants in cigarettes.


References

{{reflist, 2 Food additives Excipients