Polyglycerol polyricinoleate (PGPR), E476, is an emulsifier made from

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 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 ...

, 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, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu a ...

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

). In

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 civ ...

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 true chocolate, as it uses less-expensive hard vegetable fats such as coconut oil or palm kernel oil in pl ...

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

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 inte ...

. 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. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...

between the solid particles (e.g. cacao, sugar,

milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modula ...

) 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 elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and w ...

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 chang ...

. 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 making salads of beans (such as three bean salad), noodle or pasta salads and antipasti, and forms of potato salad. Salad dressings ...

, 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—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

bonds, with

ricinoleic acid Ricinoleic acid, formally called 12-hydroxy-9-''cis''-octadecenoic acid is a fatty acid. It is an unsaturated omega-9 fatty acid and a hydroxy acid. It is a major component of the seed oil obtained from mature castor plant (''Ricinus communis' ...

side chains connected by

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 a ...

bonds. PGPR is a yellowish,

viscous 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 inte ...

liquid, and is strongly

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

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

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

Manufacture

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 ...

is heated to above 200 °C in a reactor in the presence of an alkaline catalyst to create polyglycerol.

Castor oil Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...

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

Because 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 fat extracted from the cocoa bean. It is used to make chocolate, as well as some ointments, toiletries, and pharmaceuticals. Cocoa butter has a cocoa flavor and aroma. Its mel ...

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 has deemed PGPR to be generally recognized as safe 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 at 7.5 milligrams per kilogram of body weight. 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 goods company with headquarters in London, England. Unilever products include food, condiments, bottled water, baby food, soft drink, ice cream, instant coffee, cleaning agents, energy dri ...

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 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 America ...

." 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