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.
According to IHS Markit’s Hydrocolloids Chemical Economics Handbook published in 2019, which provides an overview of the global market for hydrocolloids (water-soluble polymers extracted from plant or animal sources, or generated in fermentation reactions). Native (unmodified) and modified starches account for the great majority (95%) of the market by weight; smaller-volume, higher-priced materials such as gelatin, guar gum, casein, xanthan gum, gum arabic, and carrageenan make up the remainder.
In 2018, China was responsible for almost half of total (starch and nonstarch) hydrocolloid consumption. In contrast, North America was the largest consumer of nonstarch hydrocolloids, largely because of its extensive use of guar gum. Western Europe and Asia were also large consumers of nonstarch hydrocolloids.
The following pie chart shows world consumption of starch and nonstarch hydrocolloids:
In the upcoming years China will drive future market growth. In 2023, China is expected to account for 65–70% of the increase from 2018 market volumes. Chinese hydrocolloid consumption is expected to rise by 4.8% per year through 2023, exceeding the world average annual growth rate of 3.3%. Other Asia and Oceania will also experience above-average consumption growth (3.7% per year) during the forecast period. All other regions will see slower growth, with average annual growth rates ranging from 0.3% in Japan to 3.1% in India.
Hydrocolloids are versatile materials with a wide range of applications. Overall demand for hydrocolloids will track growth in major end-use industries, including paper, food, pharmaceuticals, and oil and gas production.
Food applications are second in importance for starches, but they represent the single most important end use for many other hydrocolloids. Pectin serves as a gelling agent in jams, jellies, and marmalades; gum arabic inhibits sugar crystallization in soft drinks; locust bean gum maintains ice cream’s creamy texture by controlling ice crystal formation, to give just a few examples.
HERE ARE SOME OF MOST COMMON HYDROCOLLOIDS
It is derived from polysaccharide obtained from red algae. Agar is thermostable, disperses in cold or warm water and is low in viscosity. It dissolves at a temperature higher than 90oC, thickens to 35-45oC within minutes and the pH value is 2.5-10. If left uncovered, the agar dries out, but when mixed with water or other liquid, it swells and returns to its original state. Also, adding glycerol or sorbitol prevents dehydration of the gel. If a gel is used instead of pectin or gelatin then 2-3 or 10 times less agar is applied.
It is derived from polysaccharide obtained from maize. It is thermo-reversible thickener, disperses in cold water and dissolves at a temperature of 62-72oC. Its pH is between 2-3 and has a high viscosity when fully dissolved.
Gelatin comes from proteins derived from animal collagen. It is composed of very long protein molecules. These molecular chains have an affinity for their own species, so when cooled they nest together to form a three-dimensional network, trapping water molecules in the process.
It dissolves at 50oC, thickens to <15oC and melts at 25o-40oC. Tolerates alcohol up to 40%, low viscosity and pH between 4-10. 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. There are two types of gels with low and high acyl group.
The 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 90o-95oC, thickens to 10o-60oC and does not melt. Its pH is 4-10. The triggers of gelling are calcium, magnesium, sodium, potassium and acids and are low in viscosity.
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 85o-95oC and is less sensitive to ions unlike the above. The thickening and melting of this gel occurs at a temperature of 70o-80oC. Its pH is between 3-10, is high in viscosity and tolerates acids and salts.
Lecithin does not technically belong to hydrocolloids but is in this group because of its ability to modify texture. It belongs to phospholipids and is most commonly found in egg yolks, but the one derived from soybeans is commonly marketed. Lecithin has very good emulsifying properties, it improves the elasticity of flour when preparing the dough. When used to make foam, it is necessary to use wide, flat vessels to allow air to collect. Foam formation requires very little lecithin, the exact amount depends on the proportion of water and oil in the mixture. Adding too much lecithin leads to destabilization 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, e.g. when mixed with cracklings, a powder that tastes like cracklings and can be used to sprinkle food is produced. 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.
METHYL CELLULOSE (E461)
It is derived from a modified polysaccharide derived from cellulose-rich plants. When heated, methyl cellulose is a thermoversible, soft and elastic gel. When cold, it helps to form and stabilize the foam. Methyl cellulose can be dispersed in both cold and warm water with the use of a low speed mixer to prevent foam formation. If dispersed in cold water, it would be best to combine methyl cellulose with a little warm liquid first to prevent it from clotting and then add cool liquid. Also, during cold dispersion, the mixture is allowed to stand overnight and after complete dissolution some salt is added. When the gel is heated to a temperature between 50o-60oC, it begins to clot. It melts at less than 50oC, pH is 2-3 and cold gels are low and warm viscosities. The concentration of methyl cellulose in gels is usually between 1-2%. Also, alcohol increases the clotting temperature while the salt lowers it. Methyl cellulose can also be used to prevent fruit fillers from boiling in bakeries.
The pectin is derived from polysaccharide derived from citrus peel and fleshy part of the apple. It is very sensitive to pH, sugar content and cations. Natural pectin can be found in fruit, but its quantity depends on the fruit itself. In general, harder fruits like apples, oranges (bark) and plums have the most pectin, while softer fruits like grapes, cherries and strawberries have much less, because pectin is a structural molecule that binds cells.
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 40o-85oC), it does not melt and requires an acidic medium (pH <3.5), while low-methoxyl melts and in order to react it must interact with calcium ions.
XANTHAN GUM (E415)
Xanthan gum is an organic polysaccharide formed by fermentation of glucose or sucrose from plant tissues. More specifically, it is an extracellular polysaccharide produced from Xanthomonas campestris 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 it is heated only once it loses its texture. Combined with other natural gelifiers, 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, for foams and mousses 0.5-0.8%. For best performance, it is preferable to combine it with a 2:1 guar gum, in favor of xanthan.
GUAR GUM (E412)
This carbohydrate is a good stabilizer and thickener and has all the characteristics of a hydrocoid. It is obtained from 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. It is added at a concentration of 0.2-0.5% per 100 grams.
SODIUM ALGINATE (E401)
Sodium alginate is obtained by extracting from the walls of brown algae cells. It is a natural compound, formed from two types of monosaccharides: glucuronic and manuronic acids. Alginic acid and its sodium, calcium or potassium salts are offered in three different qualities due to the quality of the purification process.
It has a dual effect – dissolved in water 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, so this additive is used in the process of spherification in molecular gastronomy. It is added at a concentration of 0.5-5%.