Surface tension in food

Surface tension in food - Closeup cross section of lemon with fresh ripe juicy pulp

Based on a related question, some of us are curious about surface tension in liquids commonly used in food and drink. There's a table on Wikipedia containing a tantalizing amount of information, including:

  • The surface tension of water decreases from 76 mN/m to 59 mN/m as temperature increases from 0C to 100C. It's 72 mN/m at warm room temperature, 25C.

  • 10% acetic acid (very strong vinegar) has a substantially reduced surface tension (55 mN/m at 30C)

  • Alcohol can strongly reduce surface tension, to 46 mN/m at 11% and 30 mN/m at 40%.

  • A concentrated sucrose syrup (55%) has somewhat higher surface tension than water, 76 mN/m at 20C.

  • Very salty water (6M, compared to seawater at .6M) has higher surface tension, 83 mN/m at 20C.

Of interest would be:

  • How does surface tension typically depend on temperature? (Does it always decrease with increasing temperature?)

  • How do various everyday solutes (e.g. sugar) and mixture components (e.g. alcohol, acetic acid) affect surface tension of water? Actual data on measured surface tension of liquids would be wonderful - for example, what is the surface tension of milk, tea, vinegar, syrup, various alcoholic beverages, or anything else we commonly cook with or drink? What determines whether something increases or decreases the surface tension of water?

  • Are there any more exotic (but edible!) solutes or mixture components with dramatic effects on surface tension? Especially interesting would be ones without flavor, which could be used to tweak existing liquids.

Note: I posted a related question on the physics stackexchange.



Best Answer

This article suggests that starch gives a significant increase, and oil emulsions a significant decrease.

The same principles should apply to any small nonpolar molecule (reduces surface tension) and large molecule (increases surface tension). Note that this generally correlates strongly with viscosity. Forces at the surface forces are generally related to forces in the interior of the liquid.




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What is surface tension in foods?

Surface tension is defined as work required to extend a surface under isothermal conditions. If the surface forces take place at the interfaces, it is called interfacial tension. The methods for measuring surface tension are capillary rise, drop weight, bubble pressure, tensiometer, and dynamic methods.

Why is surface tension important in food?

Interfacial tension determines the stability of food products. Many food products like milk, margarine, mayonnaise and ice-cream are emulsions. An emulsion consists of two immiscible liquids (usually oil and water), with one liquid dispersed in the other as small droplets.

What is a good example of surface tension?

Walking on water: Small insects such as the water strider can walk on water because their weight is not enough to penetrate the surface. Floating a needle: A carefully placed small needle can be made to float on the surface of water even though it is several times as dense as water.

What are 5 examples of surface tension?

Examples of Surface Tension
  • A Drop of Liquid. ...
  • Soaps and Detergents. ...
  • Washing with Hot Water. ...
  • Clinical Test for Jaundice. ...
  • Water Striders. ...
  • Capillary Action. ...
  • Formation of a Meniscus. ...
  • Bubbles.




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Images: Karolina Grabowska, Pixabay, Lukas, Madison Inouye