What is a Hydrocolloid?
Hydrocolloids, or gums, are substances consisting of hydrophilic (dissolving in water), long-chain, high molecular weight molecules, usually with colloidal (a type of homogenous mixture) properties, that in water-based systems produce gels. In addition to their primary purpose of thickening and/or gelation, hydrocolloids often exhibit related secondary functions, such as emulsifying, whipping, suspending, and encapsulating. They are generally polysaccharides (consisting of thousands of sugar units), but gelatin (a protein) is included because its functionality and behavior in food systems is very similar to that of the polysaccharide-based gums.
Where Do They Come From ?
Hydrocolloids have been used since at least as far back in time as ancient Egypt and have been part of the human diet for several thousand years. They are produced from seeds, roots, red and brown seaweed extracts, tree sap, fruit peels, animal extracts, they are microbiological; like Xantham and gellan gums, and are also cellulose derivatives, like methylcellulose.
Types of Structure
Hydrocolloids can have linear or branched molecules. The linear type are the most abundant in nature. They are composed of one long sugar chain with side chains, which can be composed of single or multiple sugar units, or they can be as simple as carboxyl or sulfate groups. The branched type, are composed of many branches joined together in a bushy shape and typically display lower viscosities(thinner) than the linear type of the same size. Branched hydrocolloids are compact, acting like tennis balls, while the linear type act like a tangle of spaghetti moving through the solution, taking up more space. Whether its a linear or branched type, the side units coming off the backbone greatly influence the properties of the hydrocolloid and determine whether the gum is a thickening or gelling agent.
Functions and Properties
to influence the texture,
increase the stability, or
reduce fat or calories in a food product.
“Texture” usually refers to that of a finished food product. The hydrocolloid could provide extra body and mouthfeel to a beverage or give a gel structure to a milk-based dessert pudding.
To “Stabilize” a food product refers to the prevention of physical change in the product resulting from the separation of its components, i.e. a salad dressing, and the handling and processing conditions, such as high temperatures, like a pie filling melting and running subjected to oven heat.
Dispersion and Hydration