Why do french fries taste so bad when they're cold?
Is anything worse than an old, cold french fry?

One of the main reasons that french fries lose their appeal when cold is that their texture changes, said Matt Hartings, an assistant professor of chemistry at American University in Washington, D.C. .
That change in texture can be explained by the chemistry of potatoes, Hartings told Live Science. Potatoes are filled with starch, Hartings said. Starches taste good when they are "hydrated," he said.
Think of the starches in potatoes as tiny crystal spheres, Hartings said. At really high temperatures (like in fryers), water will go into those spheres and fill them up like balloons, he said. Instead of a small, hard sphere, you end up with something more "poofy," he said.
And this "poofy" texture is something people really like, Hartings said.
But as fries cool down, the water starts to move out of the crystals, and you lose the fluffy texture, Hartings said. The spheres become more crystalline and gritty, he said. And where does the water go when it leaves the starchy spheres? Right into the crust of the fry, Hartings said. That turns the crispy crust that came out of the fryer into a soggy mess.
Temperature also partially explains why the taste of fries changes as they cool down, Hartings said. Simply put, heat can heighten the flavors in foods, he said. Consider how different your morning coffee tastes when it gets cold, he added.
Finally, smell plays a big role in how a food tastes, Hartings said. Fresh french fries have a great aroma, but when they're cold, the smell is largely gone, he said. Without that smell, a lot of the flavor disappears, he said.
Eating Some Carbs, But Not Too Many, Could Help You Live Longer, Study Suggests
First there was high carb, then there was low carb and now there's ? medium carb?

First there was high carb, then there was low carb and now there's … medium carb? It may not sound as sexy, but eating carbohydrates in moderation may be best for boosting longevity, a large new study suggests.
The study, which involved more than 15,000 Americans who were tracked for a quarter of a century, found that those who ate a low-carb diet (with less than 40 percent of daily calories coming from carbs) or a high-carb diet (with more than 70 percent of daily calories coming from carbs) were more likely to die during the study period, compared with those who ate a moderate-carb diet, with about 50 to 55 percent of their calories coming from carbs.
For example, based on the findings, the researchers estimated that from age 50, people who consumed a moderate-carb diet would have a life expectancy that was about four years longer than those who consumed a very low-carb diet (with an average life expectancy of 83 years for moderate-carb eaters versus 79 years for very low-carb eaters).
But it wasn't all bad news for people following low-carb diets. In the second part of the study, published today (Aug. 16) in the journal The Lancet Public Health, the researchers examined the effect of replacing carbs with either animal-based or plant-based proteins and fats. They found that low-carb diets that involved people consuming animal-based proteins and fats were linked with a greater risk of early death, but low-carb diets that involved people consuming plant-based proteins and fats were linked with a reduced risk of early death.
Still, Seidelmann said that "if one chooses to follow a low carbohydrate diet, then exchanging carbohydrates for more plant-based fats and proteins might actually promote healthy ageing in the long term."
"On the basis of these principles, moderate intake of carbohydrate … is likely to be more appropriate for the general population than are very low or very high intakes. This would translate to a generally balanced diet that includes fruit, vegetables, legumes, whole grains, nuts, fish, dairy, and unprocessed meats—all in moderation," Mente and Yusuf wrote.
Still, the commentary called for more studies that look at the effect of eating carbs on certain biomarkers; as well as studies that randomly assign people to follow certain dietary patterns, rather than focusing on specific nutrients.