Isinglass () is a substance obtained from the dried

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their curren ...

s of

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

. It is a form of

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

used mainly for the clarification or fining of some

beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...

and

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...

. It can also be cooked into a paste for specialised

gluing Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

purposes. The English word origin is from the obsolete Dutch ''huizenblaas'' – ''huizen'' is a kind of

sturgeon Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretace ...

, and ''blaas'' is a bladder, or German ''Hausenblase'', meaning essentially the same. Although originally made exclusively from sturgeon, especially

beluga The beluga whale (/bɪˈluːɡə/) (Delphinapterus leucas) is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genus Delphinapterus. It is also known as the wh ...

, in 1795 an invention by

William Murdoch William Murdoch (sometimes spelled Murdock) (21 August 1754 – 15 November 1839) was a Scottish engineer and inventor. Murdoch was employed by the firm of Boulton & Watt and worked for them in Cornwall, as a steam engine erector for ten yea ...

facilitated a cheap substitute using

cod Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...

. This was extensively used in

Britain Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...

in place of

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

n isinglass, and in the US hake was important. In modern British brewing all commercial isinglass products are blends of material from a limited range of tropical fish. The bladders, once removed from the fish, processed, and dried, are formed into various shapes for use.

Foods and drinks

Before the inexpensive production of

gelatin Gelatin or gelatine (from la, gelatus meaning "stiff" or "frozen") is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also ...

and other competing products, isinglass was used in confectionery and desserts such as fruit jelly and ''

blancmange Blancmange (, from french: blanc-manger ) is a sweet dessert popular throughout Europe commonly made with milk or cream and sugar thickened with rice flour, gelatin, corn starch, or Irish moss (a source of carrageenan), and often flavoured ...

''. Isinglass

finings Finings are substances that are usually added at or near the completion of the processing of brewing wine, beer, and various nonalcoholic juice beverages. They are used to remove organic compounds, either to improve clarity or adjust flavor or a ...

are widely used as a processing aid in the British brewing industry to accelerate the fining, or clarification, of beer. It is used particularly in the production of cask-conditioned beers, although many

cask ale Real ale is the name coined by the Campaign for Real Ale (CAMRA) for beer that is "brewed from traditional ingredients, matured by secondary fermentation in the container from which it is dispensed, and served without the use of extraneous car ...

s are available which are not fined using isinglass. The finings

flocculate Flocculation, in the field of chemistry, is a process by which colloidal particles come out of suspension to sediment under the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. The action differs from p ...

the live

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...

in the beer into a jelly-like mass, which settles to the bottom of the cask. Left undisturbed, beer will clear naturally; the use of isinglass finings accelerates the process. Isinglass is sometimes used with an auxiliary fining, which further accelerates the process of sedimentation. Non-cask beers that are destined for

keg A keg is a small barrel. Wooden kegs made by a cooper were used to transport nails, gunpowder, and a variety of liquids. A keg is normally now constructed of stainless steel, although aluminium can be used if it is coated with plastic on th ...

s, cans, or

bottle A bottle is a narrow-necked container made of an impermeable material (such as glass, plastic or aluminium) in various shapes and sizes that stores and transports liquids. Its mouth, at the bottling line, can be sealed with an internal stopp ...

s are often

pasteurised Pasteurization American and British English spelling differences#-ise, -ize (-isation, -ization), or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mi ...

and

filtered Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter m ...

. The yeast in these beers tends to settle to the bottom of the storage tank naturally, so the sediment from these beers can often be filtered without using isinglass. However, some breweries still use isinglass finings for non-cask beers, especially when attempting to repair bad batches. Many

vegetarian Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, insects, and the flesh of any other animal). It may also include abstaining from eating all by-products of animal slaughter. Vegetarianism m ...

s consider beers that are processed with these finings (such as most cask-conditioned ales in the UK) to be unsuitable for

vegetarian diet Vegetarian diet may refer to: *Vegetarianism *Vegetarian cuisine *Plant-based diet (i.e., not necessarily stemming from vegetarian beliefs) *Veganism Veganism is the practice of abstaining from the use of animal product—particularly in die ...

s (although acceptable for

pescetarian Pescetarianism (; sometimes spelled pescatarianism) is the practice of incorporating seafood into an otherwise vegetarian diet. Pescetarians may or may not consume other animal products such as eggs and dairy products. Approximately 3% of adults ...

s). According to global data in 2018, along with low-calorie beer and gluten-free beer, beers that are acceptable for strict vegetarians are expected to grow in demand in the coming years. The demand increase is attributed to

millennial Millennials, also known as Generation Y or Gen Y, are the Western demographic cohort following Generation X and preceding Generation Z. Researchers and popular media use the early 1980s as starting birth years and the mid-1990s to early 2000 ...

consumers, and some companies have introduced vegetarian friendly options or done away with isinglass use. A beer-fining agent that is suitable for vegetarians is Irish moss, a type of

red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

containing the polymer chemical

carrageenan Carrageenans or carrageenins ( ; ) are a family of natural linear sulfated polysaccharides that are extracted from red edible seaweeds. Carrageenans are widely used in the food industry, for their gelling, thickening, and stabilizing properties. T ...

. However, carrageenan-based products (used in both the boiling process and after

fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

) primarily reduce hazes caused by

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s, but isinglass is used at the end of the brewing process, after fermentation, to remove

. Since the two fining agents act differently (on different haze-forming particles), they are not interchangeable, and some beers use both. Isinglass finings are also used in the production of kosher wines, although for reasons of

kashrut (also or , ) is a set of dietary laws dealing with the foods that Jewish people are permitted to eat and how those foods must be prepared according to Jewish law. Food that may be consumed is deemed kosher ( in English, yi, כּשר), fro ...

, they are not derived from the

beluga sturgeon The beluga (), also known as the beluga sturgeon or great sturgeon (''Huso huso''), is a species of anadromous fish in the sturgeon family ( Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basin ...

, because this fish is not kosher. Whether the use of a nonkosher isinglass renders a beverage nonkosher is a matter of debate in Jewish law. Rabbi Yehezkel Landau, in ''Noda B'Yehuda'', first edition, Yore Deah 26, for example, permits such beverages. This is the position followed by many kashrut-observant Jews today.

Egg preservative

The similar-sounding names has resulted in confusion between isinglass and waterglass, especially as both have been used to preserve eggs. A solution of isinglass was applied to eggs and allowed to dry, sealing their pores. Waterglass is sodium silicate. Eggs were submerged in solutions of waterglass, and a gel of silicic acid formed, also sealing the pores of the eggshell.

Parchment and painting conservation

Isinglass is also used to help repair

parchment Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of ...

, stucco and damage to paintings on canvas. Pieces of the best Russian isinglass are soaked overnight to soften and swell the dried material. Next, it is cooked slowly in a

double boiler A bain-marie (; also known as a water bath or double boiler), a type of heated bath, is a piece of equipment used in science, industry, and cooking to heat materials gently or to keep materials warm over a period of time. A bain-marie is also us ...

at 45 °C while being stirred. A small amount of

gum tragacanth Tragacanth is a natural gum obtained from the dried sap of several species of Middle Eastern legumes of the genus ''Astragalus'', including '' A. adscendens'', '' A. gummifer'', '' A. brachycalyx'', and '' A. tragacantha''. Some of these species ...

dissolved in water is added to the strained isinglass solution to act as 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. Altho ...

. When repairing paint that is flaking from parchment, isinglass can be applied directly to an area which has been soaked with a small amount of

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

. It is typically applied as a very tiny drop that is then guided, with the help of a

binocular microscope Binocular may refer to: Science and technology * Binocular vision, seeing with two eyes * Binoculars, a telescopic tool * Binocular microscope, binocular viewing of objects through a single objective lens Other uses * Binocular (horse), a thorou ...

, under the edges of flaking paint. It can also be used to coat tissue or

goldbeater's skin Goldbeater's skin is the processed outer membrane of the intestine of an animal, typically cattle, which is valued for its strength against tearing. The term derives from its traditional use as durable layers interleaved between sheets of gold st ...

. On paintings this can be used as a temporary backing to either canvas patches or filler until dried. Here, isinglass is similar to parchment

size Size in general is the Magnitude (mathematics), magnitude or dimensions of a thing. More specifically, ''geometrical size'' (or ''spatial size'') can refer to linear dimensions (length, width, height, diameter, perimeter), area, or volume ...

and other forms of gelatin, but it is unique in that as a dried film the

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

can be reactivated with moisture. For this use, the isinglass is cooked with a few drops of

glycerin 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 ...

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 ...

. This adhesive is advantageous in situations where minimal use of water is desired for the parchment as the isinglass can be reactivated with an ethanol-water mixture. It also has a greater adhesive strength than many other adhesives used for parchment repair.

In popular culture

In the musical ''

Oklahoma! ''Oklahoma!'' is the first musical theater, musical written by the duo of Rodgers and Hammerstein. The musical is based on Lynn Riggs' 1931 play, ''Green Grow the Lilacs (play), Green Grow the Lilacs''. Set in farm country outside the town of ...

'', the song "The Surrey With the Fringe on Top" describes the

surrey Surrey () is a ceremonial and non-metropolitan county in South East England, bordering Greater London to the south west. Surrey has a large rural area, and several significant urban areas which form part of the Greater London Built-up Area. ...

as having "isinglass curtains you can roll right down" although here the term refers to

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

, commonly used for windows in vehicle side screens (but totally inflexible).

Foods and drinks

Egg preservative

Parchment and painting conservation

In popular culture

References

Further reading