What is 'ash' relating to food nutrition

[SandWriter]

Hey All,

I was searching the USDA Nutrient Database...

http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

... and I don't know what Ash is. It seems that many foods contain some amount of it.

I'm guessing it's non-digestible stuff that's not fiber and it passes right through you, coming out your "ash".

I first noticed Ash in a nutrient list in cat food, supposedly low ash levels are good for cats? Then I saw it on the USDA web site and I started thinking, what the heck is it?

So what the heck is it? How much do you want to eat?

Thanks in advance for your help, I tried to search the archives, but ash is a three letter word.

[Bob Scene]

I'm pretty sure what they're doing is burning the food completely in a furnace and then measuring how much is left over. For example, if you start with 10 grams of cat food and burn it at 1000 degrees F in a furnace and have 2 grams of ash left over at the end, then the food was 20 % ash. Ash consists of things like oxides of sodium, potassium and magnesium, so this test gives you an idea of the mineral content of the food. High magnesium content is supposed to bad for cats with urinary problems, so that's why people worry about the ash content of cat food.

Please note that I've only tested paint and coatings for ash content, and the food industry might be doing something totally different for all I know.

[Squink]

Bob's got it in one. Ash is primarily a measure of the mineral content of food.