Polyglycerol polyricinoleate (PGPR), E476, is an

emulsifier An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althou ...

made from

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

and fatty acids (usually from

castor bean ''Ricinus communis'', the castor bean or castor oil plant, is a species of perennial flowering plant in the spurge family, Euphorbiaceae. It is the sole species in the monotypic genus, ''Ricinus'', and subtribe, Ricininae. The evolution of ca ...

, but also from

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

). In

chocolate Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either by itself or to flavoring, flavor other foods. Cocoa beans are the processed seeds of the cacao tree (''Theobroma cacao''); unprocesse ...

compound chocolate Compound chocolate is a product made from a combination of cocoa, vegetable fat and sweeteners. It is used as a lower-cost alternative to pure chocolate ''(())'' as it uses less-expensive hard vegetable fats such as coconut oil or palm kernel ...

and similar coatings, PGPR is mainly used with another substance like

lecithin Lecithin ( ; from the Ancient Greek "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...

to reduce

viscosity Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...

. It is used at low levels (below 0.5%), and works by decreasing the

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

between the solid particles (e.g. cacao,

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...

milk Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfeeding, breastfed human infants) before they are able to digestion, digest solid food. ...

) in molten chocolate, reducing the

yield stress In materials science and engineering, the yield point is the point on a stress–strain curve that indicates the limit of elasticity (physics), elastic behavior and the beginning of plasticity (physics), plastic behavior. Below the yield point ...

so that it flows more easily, approaching the behaviour of a

Newtonian fluid A Newtonian fluid is a fluid in which the viscous stresses arising from its flow are at every point linearly correlated to the local strain rate — the rate of change of its deformation over time. Stresses are proportional to the rate of cha ...

. It can also be used as an emulsifier in spreads and in

salad dressings A salad dressing is a sauce for salads, used on virtually all leafy salads. Dressings may also be used in preparing salads of beans (e.g., three bean salad), noodle or pasta salads and antipasti, and forms of potato salad. A dressing may eve ...

, or to improve the texture of baked goods. It is made up of a short chain of glycerol molecules connected by

ether In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R� ...

bonds, with

ricinoleic acid Ricinoleic acid, formally called 12-hydroxy-9-''cis''-octadecenoic acid, is a fatty acid. It is an Unsaturated fatty acid, unsaturated omega-9 fatty acid and a hydroxy acid. It is a major component of the seed oil obtained from the seeds of casto ...

side chains connected by

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

bonds. PGPR is a yellowish,

viscous Viscosity is a measure of a fluid's rate-dependent resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup h ...

liquid, and is strongly

lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...

: it is soluble in fats and oils and insoluble in water and

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

Manufacture

Glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

is heated to above 200 °C in a reactor in the presence of an

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...

ne catalyst to create polyglycerol.

Castor oil Castor oil is a vegetable oil pressed from castor beans, the seeds of the plant ''Ricinus communis''. The seeds are 40 to 60 percent oil. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its den ...

fatty acids are separately heated to above 200 °C, to create interesterified ricinoleic fatty acids. The polyglycerol and the interesterified ricinoleic fatty acids are then mixed to create PGPR.

Use in chocolate

As PGPR improves the flow characteristics of chocolate and

, especially near the melting point, it can improve the efficiency of chocolate coating processes: chocolate coatings with PGPR flow better around shapes of enrobed and dipped products, and it also improves the performance of equipment used to produce solid molded products: the chocolate flows better into the mold, and surrounds inclusions and releases trapped air more easily. PGPR can also be used to reduce the quantity of

cocoa butter Cocoa butter, also called theobroma oil, is a pale-yellow, edible Vegetable oil, fat extracted from the cocoa bean (''Theobroma cacao''). It is used to make chocolate, as well as some ointments, toiletries, and pharmaceuticals. Cocoa butter h ...

needed in chocolate formulations: the solid particles in chocolate are suspended in the cocoa butter, and by reducing the viscosity of the chocolate, less cocoa butter is required, which saves costs, because cocoa butter is an expensive ingredient, and also leads to a lower-fat product.

Safety

The

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

has deemed PGPR to be

generally recognized as safe Generally recognized as safe (GRAS) is a United States Food and Drug Administration (FDA) designation that a chemical or substance added to food is considered safe by experts under the conditions of its intended use. An ingredient with a GRAS d ...

for human consumption, and the

Joint FAO/WHO Expert Committee on Food Additives The Joint FAO/WHO Expert Committee on Food Additives (JECFA) is an international scientific expert committee that is administered jointly by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO). ...

(JECFA) has also deemed it safe. Both of these organisations set the

acceptable daily intake Acceptable daily intake or ADI is a measure of the amount of a specific substance (originally applied for a food additive, later also for a residue of a veterinary drug or pesticide) in food or drinking water that can be ingested (orally) daily ove ...

at 7.5 milligrams per kilogram of body weight. In 2017, a panel from the

European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...

recommended an increased acceptable daily intake of 25 milligrams per kilogram of body weight based on a new chronic

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

and

carcinogenicity A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and Biological agent, biologic agent ...

study. In Europe, PGPR is allowed in chocolate up to a level of 0.5%. In a 1998 review funded by

Unilever Unilever PLC () is a British multinational consumer packaged goods company headquartered in London, England. It was founded on 2 September 1929 following the merger of Dutch margarine producer Margarine Unie with British soap maker Lever B ...

of safety evaluations from the late 1950s and early 1960s, "PGPR was found to be 98% digested by rats and utilized as a source of energy superior to

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diet ...

and nearly equivalent to

peanut oil Peanut oil, also known as groundnut oil or arachis oil, is a vegetable oil derived from peanuts. The oil usually has a mild or neutral flavor but, if made with roasted peanuts, has a stronger peanut flavor and aroma. It is often used in Americ ...

." Additionally, no evidence was found of interference with normal fat metabolism, nor with growth, reproduction, and maintenance of tissue. Overall, it did not "constitute a human health hazard". A study published in the European Food Safety Authority in 2017 re-evaluated the safety of the additive and recommended to revise the acceptable daily intake and increase it to 25 milligrams per kilogram of body weight.

References

{{reflist Food additives Non-ionic surfactants Organic polymers Fatty acid esters E-number additives