Food thickeners, do you really know them?

What is a food thickener?

It is a macromolecular substance that dissolves in water and is fully hydrated under certain conditions to form a viscous, slippery solution, also known as food gum. It is an important food additive that has a wide range of uses in the food industry and is used as a gelling agent. It is used as a gelling agent to improve the physical or organisational properties of food and to make it viscous and palatable. Thickeners can also act as emulsifiers and stabilisers. They are also commonly used in the rehabilitation of patients with swallowing disorders.

What are the functions of food thickeners?

The main purpose of thickeners in food is to give the food the required rheological properties, to change the texture and appearance of the food, to form the liquid, pulpy food into a specific form, and to make it stable and homogeneous, to improve the quality of the food, so that the food has a viscous and palatable feeling. The addition of thickeners prevents the formation of excessive lumps that can make the tissue feel coarse and crumbly. In feeding aids for patients with swallowing disorders, choking reactions caused by lumpy or coarse food can be effectively avoided.

Thickeners have water solubilising and stabilising properties that refine the ice crystals generated during the freezing process and contain a large number of tiny air bubbles, resulting in a fine and homogeneous structure, smooth texture and neat appearance.

The influence of various factors on thickeners?

The influence of pH on viscosity: the pH of the medium is extremely closely related to the viscosity of the thickener and its stability. The viscosity of the thickener usually changes with the pH value. For example, the viscosity of sodium alginate is stable at pH 5 to 10; when the pH value is less than 4.5, the viscosity increases significantly (but under these conditions the viscosity is unstable due to acid-catalyzed degradation, so it is better to use it under near-neutral conditions). At pH 2 to 3, propylene glycol alginate shows the greatest viscosity, while sodium alginate precipitates and precipitates. Gelatine has the lowest viscosity at the isoelectric point, while xanthan gum (especially in the presence of small amounts of salt) has very little effect on viscosity due to changes in pH.

The effect of temperature on viscosity: As the temperature rises, the molecular movement is accelerated and the viscosity of the general solution is reduced, e.g. in the usual conditions of use of sodium alginate solution, the viscosity drops by 12% for every 5 to 6°C rise in temperature. The increase in temperature accelerates the rate of chemical reactions, especially under strong acid conditions, and most colloids hydrolyse much faster. When polymer colloids depolymerise, the drop in viscosity is irreversible: to avoid an irreversible drop in viscosity, the colloidal solution should be avoided for a long time at high temperature and subjected to heat. When a small amount of sodium chloride is present, the viscosity of xanthan gum varies very little in the range -4 to +93°C. This is a special case in thickening agents.