After we conducted our Christmas drinks test last year, we thought why not try testing Christmas sauces on our MTM! Just like the Christmas drinks, these tests are part of what is known as oral tribology, which focuses on how food and drinks feel as you eat or drink them.
There are many examples of the MTM being used to test and evaluate the properties of foods and drinks, including work to investigate the mouthfeel of wines, the creaminess of chocolates, and the richness of mayonnaise.
These sauces we’ve chosen are all incredibly important to Christmas dinners in the United Kingdom and around the world. Not only that, but they represent huge businesses and economic markets. In 2022, approximately 403 thousand tons of cranberries were produced in the United States alone, and in the UK on Christmas day around 10 million turkeys are eaten on Christmas day each year.
The sauces we chose for our testing were:
- Cranberry sauce
- Bread Sauce
- Turkey gravy
These were chosen – much like the drinks – to give us a range of different mouthfeels to investigate and compare. Turkey gravy and cranberry sauce are less thick and viscous than bread sauce, so the results vary.
To test the sauces, we used a basic set of Stribeck steps on the MTM, with a load of 10 newtons and set at a pot temperature of 35°C. The instrument was set up using PDMS specimens, which can and have been used for similar testing around the world.
The results speak for themselves and were largely what we expected:
We didn’t analyse the results too closely in this investigation, but feel free to pour over the data while you pour gravy over the your turkey!
Let’s start with the cranberry sauce and turkey gravy. Both generally show what could be considered normal lubricant behaviour entering the mixed regime, and would be perfect examples of the higher amounts of surface-to-surface contact within the mouth that would be expected with these slightly thinner sauces.
The small bump near the end of the line for cranberry sauce is an interesting point, as we believe it to be a cranberry seed being pulled into the contact, causing the momentary jump. While this does cause a slight anomaly in the data, it shows how oral tribology factors into all aspects of food testing.
The turkey gravy exhibits a lower viscosity, which would mean even more surface-to-surface contact, which is to be expected of something which is essentially a liquid, being used more to soak into food than as a dipping sauce.
Now while these are interesting results in their own right, what we didn’t foresee was that bread sauce would be the most fascinating of christmas sauces to tribologists!
The bread sauce – as you can see – behaved radically differently to the turkey gravy and cranberry sauce.
The bread sauce exhibits a significantly higher viscosity and lower friction at lower speeds compared to the two other condiments. This could be attributed to two main factors: its high viscosity – being a semi-solid containing a substantial amount of fat – and the action of fats adsorbing onto the test surfaces.
The bread sauce also behaved differently than the others by showing increased friction at higher speeds, which is the opposite of most liquids. We have a couple of theories about this:
- The composition of bread sauce, which includes an oil component in the form of a fat and water emulsion, plus bread particles acting as a thickener, is actually similar to that of a lubricating grease! Greases typically consist of a base oil thickened with metal soaps like lithium 12-hydroxystearate, suggesting that bread sauce may be acting similarly to a grease in terms of its lubricating properties.
- Or maybe the starchy bread particles are causing the sauce to shear thicken (making it a dilatant fluid) in the same way as corn starch in water behaves. A dilatant fluid behaves as though its viscosity is increasing as the shear rate increases.
Either way, it appears bread sauce is likely to feel the smoothest in the mouth, while turkey gravy provides the least lubrication.
Who knew bread sauce could be so interesting!
So there you have it! If you’re looking for the smoothest mouth feel for your Christmas sauces, go with bread sauce!
If you’d like to learn more about our machines, whether you work in the field of biotribology or think it might be relevant to your work – whatever the area of specialisation – please do get in touch with us here so we can talk through your needs and help you expand your ability to test, analyse and compare the formulations you work with.
We hope you have a merry Christmas and a happy New Year!
To stay updated with the newest industry insights through our articles and news, click here!