Ketchup or Mayo?

Let’s consider French fries for a moment. Cooked correctly, they are first fried at a lower temperature to cook the potatoes, then cooked again at a higher temperature to make them crispy. I don’t know why exactly but my experience in the US is that Greek/Middle Eastern restaurants have the best fries. No one is really sure where they developed. French and Belgium historians argue over who deserves credit for decades. One even claims it was Saint Teresa of Avila in Spain who first made them soon after potatoes arrived from the New World. However they came about, they were called French fries in the USA by 1899. The real question is ketchup or mayo?

No, we are not going to discuss poutine. Nor animal style, chili-cheese, or other variations.

But which ever condiment you favor, the properties that make it a good condiment are rheological in character. This is true of many spreads. Both steady and oscillatory shear allow us to investigate the properties, whether you are eating them on a street in Brussels or at McD’s somewhere in the US.