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Foods and Composite Materials

Aaron Goh's picture

Foods are good examples of composite materials that everyone can relate to.  From foams like ice creams to emulsions like spreads to hydrogels like jams to viscoelastic solids like cheese to porous, brittle solids like crisps, the properties of these multiphasic, heterogeneous materials are most important in the mouth where they are broken down via mechanical, chemical or thermal means.  Unlike many structural materials where the design strategy is to achieve the highest strength or toughness, foods are designed to break down in a particular manner and only under particular conditions.  A nice mechanics challenge for those who like to use the mouth as a measurement tool.

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MichelleLOyen's picture

Great post, and definitely (like biomechanics) a bit of another parallel literature where good (mostly experimental) mechanics research is done by great people but published in places that might never be on the radar for the general mechanics community.  In common with biomechanics, many studies in food mechanics are associated with viscoelastic deformation behavior.  However, I'd also like to flag the amazing fracture mechanics work being done in this community.  Peter Lucas, for example, is an anthropologist at George Washington  and studies fracture mechanics of plant materials with an interest in how  this relates to teeth and chewing in mammals.  Lots of details are available on his website.  Although widely known in this community for his pioneering work on biomimetics, Julian Vincent has also  been part of a large body of research on mechanics and food; he has interesting, completely mechanics-based explanations for things like why potato crisps are crispy and how anisotropy affects the way you bite into an apple! Recommended on this subject is "Feeding and the Texture of Food " co-edited by Vincent and published by Cambridge University Press.  A final note, just as the mechanics and biomechanics communities run into vocabularly problems and differences,  I find that with the food people too: mechanics of food usually falls under the heading of "texture studies"  and the Journal of Texture Studies publishes lots of mechanics-of-food research!

Aaron Goh's picture

Michelle, you are right in saying that there is parallel between food mechanics and biomechanics, including the field of haptics.  They are also closely integrated, i.e. when the consumer interacts with the food, either via the fingers or in the oral cavity or in the digestive system.

I think food scientists to be traditionally strong in gelation since many foods are gels at one stage or another.  In certain cases, formation of gels is unwanted and an indication of instability in the structure.  So there are many publications in gelation mainly in physics and rheology journals.  However, finding good papers in solid and fracture mechanics is more a hit or miss event, since the area is rather applied and most are not trained or interested in mechanics per se. But there is plenty of scope for good, useful mechanics.

The father of psychophysics, Sir Scott Blair, used to publish very interesting papers on the influence of viscoelastic properties (he was very interested in the Nutting equation) on 'gestalt' - human sensory experience.  Sadly, his simple yet fundamental techniques have been completely bypassed by current-day researchers, who prefer the trial-and-error statistical curve fitting methods.

 

Zhigang Suo's picture

Fascinating stuff!  Can you point us to papers on fracture of gels?

Aaron Goh's picture

Zhigang, that is a pretty tough request. There are simply too many publications to cite here, especially when they are so many different types of gels too! Without meaning to be exhaustive :

Norton IT, Frith WJ. 2001. Microstructure design in mixed biopolymer composites. Food Hydrocolloids 15 543
Liu z, Scanlon MG. 2003. Predicting mechanical properties of bread crumb. Transactions of IChemE 81 224
Barnes HA. 1994. Rheology of emulsions - a review. Colloids and Surfaces A:Physicochemical and Engineering Aspects 91 89
Stading M, Langton M, Hermansson AM. 1995. Small and large deformation studies of protein gels. Journal of Rheology 39 1445
Dobraszczyk BJ, Morgenstern MP. 2003. Rheology and the breadmaking process. Journal of Cereal Science 38 229
Luyten H, van Vliet T. 2006. Acoustic emission, fracture behavior and morphology of dry crispy foods: a discussion article. Journal of Texture Studies 37 221
Bot A, van Amerongen IA, de Groot R, et al. 1996. Large deformation rheology of gelatin gels. Polymer Gels and Networks 4 189

I myself was trained here : http://www3.imperial.ac.uk/foodtechnology

Aaron Goh's picture

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Zhigang Suo's picture

Dear Aaron:  Thank you so much for getting us started on this.  We have just begun to learn about gels, mostly in the context of soft active materials (SAMs), but would like to learn how other people have studied similar materials.  We will study these papers, and will most likely come back to you for more instruction.

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