An Introduction to Food Colloids

An Introduction to Food Colloids

 

 

An Introduction to Food Colloids

The 2018 Food Colloids Conference was held this week at the University of Leeds in the UK. It was an amazingly well organized conference, and packed full of both interesting research and interesting people. It was a great opportunity to meet with like-minded researchers across academia and industry as well as to get up-to-date on the latest trends in food colloids research. I thought it would be interesting to write somewhate of an introduction to the subject.

Colloids

The word “colloid” is derived from the Greek word “kola” for glue, and first came into use in the 1860s to distinguish between colloids and “crystalloids” such as sugar and salt. The modern usage of colloids refers to a type of heterogeneous suspension of particles between 1-1000nm.

What many people do not realise is that colloids are ubiquitous in our everyday life. Emulsions, foams, and gels are all colloidal. Below is a list of common examples in our day-to-day life:

  • Aerosols
  • Agrochemicals
  • Blood
  • Butter
  • Cement
  • Cosmetics
  • Detergents
  • Fabrics
  • Foams
  • Fog
  • Ice Cream
  • Ink
  • Milk
  • Paint
  • Paper
  • Pharmaceuticals
  • Plastics
  • Rubbers
  • Smoke

Colloids were unknowingly first discovered by the Scottish botanist Robert Brown in 1827, while studying the movement of pollen grains in water under a microscope. He noticed an unusual zigzagging motion in the water. Scientists later recognized this motion as a distinct characteristic of colloids and named it “Brownian motion” in honour of the man that first observed it. Brownian motion is caused by the collision of the solvent molecules (i.e. water molecules) with the colloids, causing the colloids to be in constant, random motion.

Another unique characteristic of colloids is the Tyndall effect, named after the English physicist John Tyndall. The Tyndall effect is the ability of colloids to scatter light, notable in the appearance of smoke and dust floating in the air. Milk is white because of the Tyndall effect, as upon passing through it, the light is scattered by the suspended fat and protein particles.

Although colloids are broadly relevant in many different fields of research, it is particularly important in food. Almost all foodstuffs may be considered colloidal, i.e. consisting of particles: oil droplets, air bubbles, starch granules, cell walls, etc., dispersed in a continuous phase. In most cases, the characteristics of the colloidal particles are directly responsible for the perception, acceptability, and digestibility of the product. In addition, most forms of food processing (i.e. storage, freezing, chilling, cooking, mixing, blending) have some modifying effect on the properties of the colloidal particles.

Colloid science, rheology, surface, and interfacial science are all part of the field of research that has become known as ‘soft matter’ and is becoming one of the most active areas of study in physics, biophysics, physical chemistry, and food science.

 

 

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