Isinglass: Characteristics, Properties and How to Use it in the Kitche
Isinglass or “ichthyol glue” – in English: isinglass – is the common name of an ingredient / additive (E441) based on collagen ( proteins ), with a thickening and gelling function , very widespread both in home cooking and in industry – food, cosmetic, pharmacological, etc.
Also read the nutritional evaluation of isinglass and the article on jellies .
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“By definition”, isinglass would be obtained from the drying and shredding of the swim bladder of fish, but also of their cartilage – typical of the biological class Chondrichthyes, to which, for example, sharks, rays and sturgeons belong. Today, however, the product most marketed in Italy, despite being called by the same name, is mainly obtained from the fifth quarter of large land mammals for slaughter (mainly pigs, but also cattle), in particular from the skin (commonly known as rind or cotica ) and from the cartilages.
In Italy, the word “isinglass” is improperly used as a synonym for “edible gelatine”; it is actually a rather gross semantic error, or an imprecision. In fact, as we have said, although it is still produced and marketed today, fish collagen has been largely replaced by that obtained from pigs and cattle, better identified as “sheet gelatine”. Secondly, currently, most “food jellies” are plant- or algal-derived; gums, mucilages and other similar polymers are a typical example . The most common are: guar gum , xanthan gum , tara gum , konjac gum, psyllium cuticle flour , agar agar , pectin etc.
In addition to the strong thickening and gelling capacity, the main characteristic that all these products have in common is their solubility in water or in any case in hydrophilic compounds; for the rest, these are molecules with chemical-physical properties that are sometimes quite different from each other. There are therefore many differences that make one gelatin more suitable than another. In practice, the choice and application of edible jellies can change based on the result you want to obtain – consistency, tolerance to acid or basic pH, colour, translucency, tactile sensation, etc. – the nutritional or philosophical needs of consumers – see allergies food , intestinal pathologies, vegetarian or vegan diet , Muslim, Jewish, Hindu, Buddhist religion – etc.
Did you know that…
Most of the world’s isinglass production is used to clarify or refine beer and wine . It can also constitute a sort of highly specific “gluing paste”.
Nutritional properties
Nutritional properties of isinglass
For most additives it would be useless to open a paragraph on their nutritional properties. In the case of isinglass, however, it is useful to say at least a few words about it.
First of all we must specify that, with the exception of allergic forms , there are no documented adverse reactions involving isinglass or gelatine based on terrestrial animal collagen. It may seem superfluous but, as it is a food additive ( E441 ), many consumers are led to believe that in considerable doses it can have a negative influence on health. It is not so.
In fact, isinglass is pure collagen, made up only of proteins. It provides approximately 340 kcal / 100 g but, if we consider that approximately 1 g of pudding is used, its nutritional value, as well as its impact on the diet, are almost nil.
Anti-cellulite dessert – Blueberry and gotu kola aspic
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Instead, consideration should be given to the suitability of philosophical or religious nutritional regimes. All animal jellies are to be avoided in vegetarian diets, Hinduism and Buddhism. Those from kosher and halal fish are relevant in Judaism and Muslimism; however, the sturgeon is considered an impure animal and should therefore be avoided. The same people abhor pigs but not cattle, if slaughtered according to certain criteria.
Uses
Isinglass in the kitchen
Before collagen was obtained from the cartilage and skin of land animals, thickeners and gelling agents were made from isinglass. This was commonly used in sweet pastries in many recipes, for example fruit jellies, white puddings – such as blancmange – etc.
Truth be told, edible jellies all serve the same purpose. Many know, however, that “thickening” and “gelling” are not exactly the same thing. For example, a custard must be “creamy”, not simply “thick” and certainly not “gelatinous”. On the contrary, a fruit jam should have a solidified consistency, therefore dense, not creamy or gelatinous. And again, speaking of a pudding, it is essential that it has the structure and jiggle of a jelly, it must not fall apart or even stick to the mold.
Isinglass, or rather all animal collagens, above all have a gelatinizing capacity; another example is agar agar. Pectins, on the other hand, are more suitable for thickening, especially aqueous mixtures rich in sugars . To increase the creaminess, however, emulsions of fat and water rich in lecithins are especially suitable .
However, animal collagens are not suitable, for example, for jams or even for creams. This does not mean that, if used in small doses, they are not able to increase the body of the recipe; on the other hand it is not their primary function.
To get an idea of what the natural consistency of isinglass might be, simply look at the refrigerated meat broth ; if well concentrated and kept at 4-5 °C, it takes on a typically “trembling” consistency, and liquefies as soon as it is heated. In this case, the collagen comes from the connective tissues of the meat which tend to dissolve when boiled.
Isinglass is also still used to optimize the preservation of certain canned products, both for human consumption – see jellied meat – and for animal consumption, such as wet cat food ; Below we offer you a homemade recipe for your four-legged friend.
Wet Food for Cats – Homemade Jelly Meat
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Isinglass to clarify and refine drinks
Isinglass finings are widely used in Great Britain as precipitation and clarification accelerators in the brewing industry. It is, essentially, a chemical process that replaces physical microfiltration and as such does not require heat treatments or membranous steps.
Isinglass-based finings find particular application in the production of raw beers (cask-conditioned or cask ales), although some products that are not subjected to this process are still available. Added to “raw” beer, these flocculate the live yeasts forming a gelatinous mass which tends to precipitate. By avoiding agitating the liquid or otherwise moving the deposit at the bottom, this allows the beer to clear naturally and more quickly than normal.
Did you know that…
Flocculation is a chemical-physical mechanism that affects colloidal systems, in which the solid phase tends to separate, forming flocs in suspension.
Non-cask beers on the other hand are generally pasteurized , which allows for rapid precipitation with deposit, easily removed through physical filtration. Obviously, the heat treatment alters the organoleptic and gustatory characteristics of the beer, and kills the yeasts.
The use of isinglass in the production of raw beer is currently decreasing, although it is a rather effective method for recovering the most impure batches.
Although only traces of isinglass can be identified in the finished beer, many vegetarians consider these drinks – still widespread today, especially in the United Kingdom – unsuitable for their diet. Therefore a vegetal alternative has been proposed, in an attempt to reproduce the same clarifying power; this is the case of carrageenan extracted from crondo crispo or carragheen (genus Chondrus and species crispus ), a type of red algae . This polysaccharide is used both during the thermal process and after fermentation, but above all it reduces the concentration of the suspended protein mass and not that of the microorganisms . In contrast, isinglass is mainly used to remove yeasts. Because the two fining agents work differently, to the detriment of vegetarians, they are not actually interchangeable and many beers use both.
Isinglass finings are also used in the production of kosher wines – i.e. permitted by the Jewish religion – although for kashrut reasons they cannot derive from beluga sturgeon, considered impure and therefore not kosher.
Isinglass as a food preservative
Isinglass was used as a preservative in the 1940s, before and during the Second World War, especially in Great Britain. It was dissolved in water, typically in a bucket, into which the fresh eggs were immersed .
Isinglass as a preservative for parchments
Isinglass is used for the restoration of parchments. After soaking in water and cooking at 45°C, with the addition of decanted tragacanth ( emulsifier ), a very useful compound is obtained for repairing the flaking paint of these manuscripts – previously softened with ethanol . This can be applied directly to the spot, in very small drops, which are then guided with the help of a binocular microscope, under the edges of the flaking paint.
Isinglass can also be used to coat the fabric itself. Here, the isinglass is applied superficially and has the characteristic of being able to be reactivated with humidity, for example with an ethanol-water mixture. For this use, it is usually cooked with a few drops of glycerin or honey . This adhesive is especially beneficial in situations where you want to use very little water. It also has greater adhesive strength than many other products used for parchment repair.
History
Historical notes of isinglass
Although it was originally produced exclusively from the “beluga” sturgeon ( Huso genus and Huso species ), typical of the seas and rivers located in north-eastern Euro-Asia, in 1795 William Murdoch introduced the use of cod , which was more available and cheap. From then on, especially in Great Britain, cod isinglass replaced the imported Russian one.
Curiosity
The etymological origin of the term is most likely related to the Dutch noun “huizenblaas”, now considered obsolete. “Huizen” is the name of a species of sturgeon, while “blaas” is the term for a swim bladder. In German, “hausen blas” has essentially the same meaning.
