Isinglass is a substance obtained from the dried swim bladders of
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
. It is a form of
collagenCollagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
used mainly for the clarification of
wineWine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
and
beerBeer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
. It can also be cooked into a paste for specialized gluing purposes.
Isinglass was originally made exclusively from
sturgeonSturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common...
, especially
Beluga sturgeonThe beluga or European sturgeon is a species of anadromous fish in the sturgeon family of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea...
, until the 1795 invention by
William MurdochWilliam Murdoch was a Scottish engineer and long-term inventor.Murdoch was employed by the firm of Boulton and Watt and worked for them in Cornwall, as a steam engine erector for ten years, spending most of the rest of his life in Birmingham, England.He was the inventor of the oscillating steam...
of a cheap substitute using
codCod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
. This was extensively used in
BritainThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
in place of
RussiaRussia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n isinglass. The bladders, once removed from the fish, processed and dried, are formed into various shapes for use.
Use in foods and drinks
Prior to the inexpensive production of
gelatinGelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
and other competitive products, isinglass was used in confectionery and desserts such as fruit jelly and
blancmangeBlancmange is a sweet dessert commonly made with milk or cream and sugar thickened with gelatin, cornstarch or Irish moss, and often flavored with almonds. It is usually set in a mould and served cold. Although traditionally white, blancmanges are frequently given a pink color as well...
.
Isinglass
finingsFiningsThe term is a mass noun rather than a plural. are substances that are usually added at or near the completion of the processing of brewing wine, beer and various nonalcoholic juice beverages. Their purpose is for removal of organic compounds; to either improve clarity or adjust flavor/aroma...
are widely used as a processing aid in the British brewing industry to accelerate the fining, or clarification, of beer. They are used particularly in the production of cask-conditioned beers, known as real ale, although there are a few
cask aleCask ale or cask-conditioned beer is the term for unfiltered and unpasteurised beer which is conditioned and served from a cask without additional nitrogen or carbon dioxide pressure...
s available which are not fined using isinglass. The finings
flocculateFlocculation, in the field of chemistry, is a process wherein colloids come out of suspension in the form of floc or flakes by the addition of a clarifying agent. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually...
the live
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
in the beer into a jelly-like mass, which settles to the bottom of the cask. Left undisturbed, beer will clear naturally; however, 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
kegA keg is a small barrel.Traditionally, a wooden keg is made by a cooper used to transport items such as nails, gunpowder., and a variety of liquids....
s,
canA beverage can is a tin can designed to hold a specific portion of a beverage. Beverage cans are made of tin-plated steel or aluminium.- History :...
s or
bottleA bottle is a rigid container with a neck that is narrower than the body and a "mouth". By contrast, a jar has a relatively large mouth or opening. Bottles are often made of glass, clay, plastic, aluminum or other impervious materials, and typically used to store liquids such as water, milk, soft...
s are often
pasteurizedPasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...
and
filteredFiltration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...
. 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.
Although very little isinglass remains in the beer when it is drunk, many vegetarians consider beers that are processed with these finings (such as
GuinnessGuinness is a popular Irish dry stout that originated in the brewery of Arthur Guinness at St. James's Gate, Dublin. Guinness is directly descended from the porter style that originated in London in the early 18th century and is one of the most successful beer brands worldwide, brewed in almost...
and most real ales) to be unsuitable for vegetarian diets (although acceptable for pescetarians). A beer-fining agent that is suitable for vegetarians is Irish moss, a type of red alga also known as
carrageenanCarrageenans or carrageenins are a family of linear sulfated polysaccharides that are extracted from red seaweeds. There are several varieties of carrageen used in cooking and baking. Kappa-carrageenan is used mostly in breading and batter due to its gelling nature...
. However, carrageenan-based products (used in both the boiling process and post-fermentation) primarily reduce hazes caused by
proteinProteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, but isinglass is used at the end of the brewing process, after fermentation, to remove
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
. Since the two fining agents act differently (on different haze-forming particles), they are not interchangeable, and some beers make use of both.
Isinglass finings are also used in the production of
kosher wineKosher wine is grape wine produced according to Judaism's religious law, specifically, Jewish dietary laws .To be considered kosher, Sabbath-observant Jews must be involved in the entire winemaking process and any ingredients used, including finings, must be kosher...
s, although for reasons of
kashrutKashrut is the set of Jewish dietary laws. Food in accord with halakha is termed kosher in English, from the Ashkenazi pronunciation of the Hebrew term kashér , meaning "fit" Kashrut (also kashruth or kashrus) is the set of Jewish dietary laws. Food in accord with halakha (Jewish law) is termed...
they are not derived from the Beluga sturgeon, as this fish is not kosher. Whether the use of a non-kosher isinglass renders a beverage non-kosher is a matter of debate in Jewish law. Rabbi Yehezkel Landau, in Noda B'Yehuda, first edition, Jore Deah 26, for example, permits such beverages. This is the position followed by many kashrut-observant Jews today.
Use in parchment conservation
Isinglass is also used to help repair
parchmentParchment is a thin material made from calfskin, sheepskin or goatskin, often split. Its most common use was as a material for writing on, for documents, notes, or the pages of a book, codex or manuscript. It is distinct from leather in that parchment is limed but not tanned; therefore, it is very...
. Pieces of the best Russian isinglass are soaked overnight to soften and swell the dried material. Next, it is cooked slowly in a
bain-marieA bain-marie is a French term for a piece of equipment used in science, industry, and cooking to heat materials gently and gradually to fixed temperatures, or to keep materials warm over a period of time.- Description :...
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 that area which has been pre-wet with a small amount of
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
. It is typically applied as a very tiny drop that is then guided, with the help of a binocular microscope, under the edges of flaking paint.
It can also be used to coat tissue or
goldbeater's skinGoldbeater's skin — the outer membrane of calf's intestine — is a parchment traditionally used in the process of making gold leaf by beating, reducing gold into mere 1μm-thick leaves....
. Here isinglass is similar to parchment size and other forms of
gelatinGelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
but it is unique in that as a dried film the
adhesiveAn adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
can be reactivated with moisture. For this use the isinglass is cooked with a few drops of glycerin or
honeyHoney is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
.
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. (Quandt, 1996)
See also
- Thin transparent sheets of mica called "isinglass"
- Sodium silicate used in food preservation colloquially called "isinglass"