iStock_000022961411 300x270It is time to pop on my curly false moustache and chef’s hat to become high, mighty and judgmental about what has been bothering me lately: the ‘not so’ culinary delights on the rheology road….

I travel – a lot! On my travels, I experience a variety of ‘on-the-go’ foods and hotel restaurant experiences. Since I am a rheology specialist and food science and texture ultimately encompasses the science of rheology, I have a tendency to overanalyze everything I eat.

Ketchup spoon

Sauces, custards, creams and gravies… viscosity and consistency…it bothers me! We’ve all experienced the upset of a disappointing dipping sauce and the curdled creams and custards. My real beef however, is when the viscosity is just all wrong and there is no partitioning between cranberry sauce, gravy and turkey and it becomes one big mixed up mess. Goldilocks knew what she was talking about. I too, want my porridge to be perfect!

Sometimes, however, it is not just the rheology that lets you down during dinner. For the chef (you know who you are) who used mint sauce (the lamb variety) on my sticky toffee pudding, thinking it was a good idea (?!), this should result in an automatic ban from any kitchen!!

We can test many properties of food with a rheometer…with the exception of mint sauce and sticky toffee pudding flavour compatibility. In fact, we can even use a rheometer to mimic mastication through compression, shear and decompression cycles on a food sample. This means we can objectively establish differences between foods in terms of their consistency, yield stresses, stickiness and adhesion.

bowl of tomato sauce ketchupThe ‘yield stress’ is the reason we need to squeeze or whack our dipping sauce out of its bottle and is what makes it stationary on our plates. It is also the result of that satisfying feeling that allows us to dunk, dip and scoop that hot and fluffy potato chip (or you can imagine a carrot and hummus situation for those who prefer a healthier option). We can even compare branded and supermarket’s own ‘value options’ to see if those extra dollars make the difference in ‘the dip’.

Yield Stress_tomatoIt is not only sauces that catch my eye when travelling the globe or browsing the supermarket shelves. The alcoholic beverage section offers both rheological education and entertainment, should you wish to indulge. Gold leaf suspended in Vodka?!! Now who would have ever dreamed of such a magical thing? This is something I imagine robe-cladded Greek (or maybe Russian?) gods to be drinking on white horses. Despite how strange these drinks may appear, for many the excitement behind the gold suspension remains the same. How can an apparent low viscosity and drinkable fluid suspend gold?? The answer is ‘yield stress’, of course! The suspending power usually results from the weak association of polysaccharide gel particles which form a so-called ‘fluid gel’, which behaves like a gel on the shelf but a fluid in the mouth.

Food rheology plays a part in almost everything we eat and drink and keeps consumers happy without them even being aware of it!

So, next time your runny sauce looks up at you from your plate, all sad-eyed and watery, you’ll understand its misery!

If you have any food failures or meals that really grate on you, please comment or share photos via Twitter, Facebook or Linkedin.! I share your pain (au chocolat)!

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