Hydrocolloids: What are they and what is their place in the kitchen?
A hydrocolloid can be defined as a gel-forming substance when it comes in contact with water. Such substances also include polysaccharides and proteins capable of one or more of the following: gelling, foam stabilization, emulsions, dispersions, and prevention of crystallization of saturated water or sugar. In this blog post, we will cover a few hydrocolloids most commonly used in the kitchen. Note: Every time we mention “degrees”, they are in Celsius.
Agar is derived from polysaccharides obtained from red algae. It is commonly used as a vegan substitute for gelatin. Unlike gelatin, it is thermostable, dissolves at a temperature higher than 90 degrees, and thickens to 35–45 degrees within minutes. In case agar is left uncovered, it will dry out but when mixed with water or other liquid, it will swell up and return to its original state. Also, adding glycerol or sorbitol prevents dehydration of the gel. Agar is great at stabilizing, texturizing, and thickening beverages, dairy products, sauces, etc.
Corn starch is derived from polysaccharides obtained from maize. It is a thermo-reversible thickener, meaning, that the thickened food can melt when in contact with heat. It disperses in cold water and dissolves at a temperature of 62–72 degrees. This hydrocolloid is usually used to make paste or custard and it’s used rather than flour because it forms a translucent compound.
Gelatin comes from proteins derived from animal collagen. It dissolves at 50 degrees, and melts at 25-40 degrees, and tolerates alcohol up to 40%. If gelatin leaves are used, they should be placed in water to flourish, then drained and dissolved in the desired liquid. If gelatin powder is used, it should be allowed to flourish and dissolve in the same liquid.
Gelan originates from polysaccharides obtained by fermentation of Sphingomonas elodea. Low acyl group gel is a transparent, thermo-reversible, heavy, and brittle gel. The dispersion is carried out in cold water and can be improved (allowing hot solutions to be added) by adding sugar (3–5x), glycerol, alcohol, or oil (3–5x). Dissolution occurs at 90-95 degrees, thickens to 10-60 degrees, and does not melt. High acyl group gel is an opaque, thermoreversible, soft, and elastic gel. The dispersion is carried out under the same conditions as with the low acyl group gels. Dissolution occurs at a temperature between 85-95 degrees and is less sensitive to ions unlike the one above. The thickening and melting of this gel occur at a temperature of 70-80 degrees. It’s high in viscosity and tolerates acids and salts. It’s mainly used to stabilize water-based gels, such as desserts and drinking jellies.
Lecithin does not technically belong to hydrocolloids but because of its ability to modify texture, it’s listed here. It belongs to phospholipids and is most commonly found in egg yolks, but the one derived from soybeans is commonly marketed. It has great emulsifying properties and improves the elasticity of flour when preparing the dough. Lecithin is also used to make foam, and for that action using wide, flat vessels that will allow air to collect is necessary. Foam formation requires very little lecithin, the exact amount depends on the proportion of water and oil in the mixture. A crucial thing to know is that adding too much lecithin leads to destabilizing the attainment of the foam.
Maltodextrin is a polysaccharide obtained by the breakdown of corn, wheat, potato, or tapioca starch. It is made in the form of a tasteless powder to which different flavors are added. When absorbing the oil, it retains its powder state. For example: when mixed with cracklings, it creates a powder that tastes like cracklings and can be used to sprinkle food. It dissolves well in water and is easily digestible. Since maltodextrin is a type of sugar, it can be mixed with the desired food and caramelized. When mixed with the gel, it helps to dissolve it in water.
Methylcellulose is derived from a modified polysaccharide of cellulose-rich plants. When heated, methylcellulose is a thermoreversible, soft, and elastic gel. When cold, it helps to form and stabilize the foam. It can be dispersed in both cold and warm water with the use of a low-speed mixer to prevent foam formation, and it would have been best to combine it with a little warm liquid first to prevent it from clotting, and then add cool liquid. When the gel is heated to a temperature between 50-60 degrees, it begins to clot, but melts at less than 50 degrees, with cold gels that have warm viscosities. The concentration of methylcellulose in gels is usually between 1–2% and can be used to prevent fruit fillers from boiling in bakeries. Note: alcohol increases the clotting temperature while salt lowers it.
Pectin is derived from polysaccharides derived from citrus peel and the fleshy part of the apple. It is very sensitive to pH, sugar content, and cations. There are two types of pectin: low and high methoxyl content. Both are dissolved in water and are dosed in the amount of 0.15–3.1%. The difference between the two types is that high-methoxyl does not dissolve if more than 25% of sugar is present in the solution (its optimum temperature is 40-85 degrees), it does not melt and requires an acidic medium, while low-methoxyl melts and to react it must interact with calcium ions.
Xanthan gum is an organic polysaccharide formed by fermentation of glucose or sucrose from plant tissues and is used as a thickening agent, emulsifier, stabilizer, and sedimentation agent. It dissolves easily in any liquid, hot or cold, at all temperatures and pHs, but if heated, even once it loses its texture. Combined with other natural qualifiers, it can be used to prepare jellies that are resistant to high acidity, which is not the case with traditional varieties of the same. In the process of spherification, it can serve as an aid to facilitate the preparation of large spheres. It is dosed in the amount of 0.25% for liquid effect, 0.7–1.5% for density, and foams and mousses 0.5–0.8%. For best performance, it is preferable to combine it with a guar gum with a proportion of 2:1 in favor of xanthan.
Guar gum is a good stabilizer and thickener that has all the characteristics of a hydroid. It is obtained from the legume (Cyamopsis tetragonolobus), which is similar to peas and is grown in India and Pakistan. Guar gum has a great ability to bind water, as much as four times that of carob rubber, 8 times that of starch, and even 16 times that of flour. Its most common use, along with xanthan, is to increase the elasticity of gluten-free products and is added at a concentration of 0.2–0.5% per 100 grams.
Sodium alginate is obtained by extracting it from the walls of brown algae cells. It is a natural compound, formed from glucuronic and mannuronic acids. Alginic acid and its sodium, calcium, or potassium salts are offered in three different qualities due to the quality of the purification process. This compound has a dual effect — when dissolved in water, it increases the density of the solution and its viscosity, and when it comes into contact with the liquid containing calcium, a gelatinous membrane is formed, which is why sodium alginate is used in the process of spherification in molecular gastronomy. When used in the spherification process, it is added at a concentration of 0.5–5%.
This would be all for this post. It’s a bit long, but it’s meant to give correct and important pieces of information. If you would like to get recipes that include some of these hydrocolloids or to learn more, comment and follow.
