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Isinglass () is a substance obtained from the dried swim bladders 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 ...
. It is a form of collagen 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, 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 Although originally made exclusively from sturgeon, especially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. 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 transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...
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 and other competing products, isinglass was used in confectionery and desserts such as fruit jelly and '' blancmange''. Isinglass finings 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 ales 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 constit ...
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 stop ...
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. Vegetariani ...
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 diet ...
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 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 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) 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, res ...
s, but isinglass is used at the end of the brewing process, after fermentation, to remove
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 constit ...
. 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, they are not derived from the beluga sturgeon, 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 o ...
, 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 ...
at 45 °C while being stirred. A small amount of gum tragacanth dissolved in water is added to the strained isinglass solution to act as an emulsifier. 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 with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
. 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 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. Size can also be m ...
and other forms of gelatin, but it is unique in that as a dried film the adhesive 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 ...
or
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 written by the duo of Rodgers and Hammerstein. The musical is based on Lynn Riggs' 1931 play, ''Green Grow the Lilacs''. Set in farm country outside the town of Claremore, Indian Territory, in 1906, it tell ...
'', the song "The Surrey With the Fringe on Top" describes the surrey as having "isinglass curtains you can roll right down" although here the term refers to mica, commonly used for windows in vehicle side screens (but totally inflexible).


References


Further reading

* {{cite book , last = Davidson , first = Alan , title = Oxford Companion to Food , year = 1999 , isbn = 0-19-211579-0 , page
407
, chapter = Isinglass , chapter-url-access = registration , chapter-url = https://archive.org/details/oxfordcompaniont00davi_0/page/407 * Woods, Chris (1995). "Conservation Treatments for Parchment Documents", ''Journal of the Society of Archivists'', Vol. 16, Issue 2, pp. 221–239.
Chemozyme
Brewing ingredients Winemaking Fish products Food ingredients Conservation and restoration materials