lime lore...(includes calcium hydroxide)

Lime (Chemical)

http://www.practicallyedible.com/edible.nsf/encyclopaedia!openframeset

The chemical Lime is used in some food processing, and has been for millennia.It's important to first understand the types of Lime. Lime starts out as calcium carbonate. Calcium carbonate can be derived from Limestones, coral, chalk or from the shells of mollusks such as oysters or clams. Heating the substance drives out carbon dioxide, leaving Calcium Oxide. That is one type of Lime. From Calcium Oxide, another type of Lime, which is Calcium Hydroxide, is derived.

The distinction between Calcium Oxide and Calcium Hydroxide is very important. Many food writers mix these up, giving out potentially dangerous information. Calcium Oxide is very dangerous; never use it. Lime is used in South America in processing corn. Corn is soaked in water to which Lime has been added. The corn swells, loosening the husks. The corn is then rinsed to wash away both the Lime water and the husks. This has been done for millennia. Though this was a very efficient way to husk the kernels of corn, negating the need for tiresome work or advanced tools and machinery, there was a vital nutritional side-benefit that happened, even though people didn't realize it.

In addition to adding a bit of calcium, more importantly, the process released the niacin in the corn and made it available to the body. The connection between Lime treatment, niacin and pellagra was not made until the 1930s. New World natives began developing pellagra when they were put on reserves and given food, especially untreated corn. After the corn is treated in this way, it can be dried and ground into a corn flour such as "Masa Harina".Tortillas are made from Masa Harina, which is the flour made from corn treated with the chemical Lime. It gets somewhat confusing, though, when you learn that Mexicans, such as those in Monterrey, Mexico will sometimes add Lime when they are making Tortillas.

At this stage in the game, though, what they are adding is juice from the Lime fruit, not Lime the chemical.The chemical Lime can also be used in making sugar -- it helps the cane pulp matter in the sugar syrup to coagulate, so that it can be removed.

Lime is also used in pulp and paper industry to soften the lignin in wood to make paper.Calcium OxideCalcium Oxide is also called Quicklime (when water is added, it heats up and bubbles like it's boiling, make it seem alive. "Quick" used to be used in a sense that meant alive, as in the "quick and the dead"). It is also called unslaked Lime.It is very dangerous to use, as it will react with any water, even the slightest amount of perspiration or moisture on your skin, and burn you severely.

The steam given off is not toxic, but it is very hot and can scald and burn.

Calcium Hydroxide

To make Calcium Hydroxide (aka Edible Lime, Hydrated Lime, CaH2O2), Quicklime is treated with water. It heats up, evaporates the water, and leaves behind a white powder. This converts Quicklime from Calcium Oxide to Calcium Hydroxide.
When Calcium Hydroxide is mixed in water, it creates a very alkaline solution. This is also called slaked Lime, as the Lime has been treated with as much water as it will take up, "slaking" (satisfying) its thirst.

Pickling Lime

Pickling Lime is Calcium Hydroxide. It's also called "food-grade Lime", because in making the Calcium Hydroxide the processors make sure that the process remains pure and doesn't introduce anything untoward (e.g. it's not done in rusty old bins).

Pickling Lime helps to improve the firmness of pickles by introducing calcium that reinforces the pectin in the vegetable being pickled. In using it, a vegetable such as cucumber is soaked first in water mixed with the pickling Lime, for up to a day, then rinsed thoroughly -- at least 3 times -- before the actual pickling process begins.

Because the Lime is alkaline, you have to get rid of it all, or it would neutralize the acidity that you are going to use to preserve the pickles with. People haven't always rinsed it thoroughly, though, leaving some alkalinity and lowering the pH of the pickling batch by neutralizing the acidity. On account of this, cases of botulism have been recorded, and *for that reason it's not generally recommended to use this anymore.

*this explains why it's hard to find, in Canada.


Some swear by using grape leaves instead to help with crunchiness instead of using Lime.

Don't substitute any industrial Lime, whether agricultural or lumberyard Lime, as that may contain contaminants.

Agricultural Lime

Ground Limestone, not Lime.


Literature & Lore

Calcium Oxide has a very high melting temperature, 2572°C. It can be heated so hot that it will emit a white light without melting. Before theatres used electricity to power the stage lights, Lime would be heated with a flame, to give off a light directed at the stage -- and voilà, you had the "Limelight".
I'm ready, Mr DeMille.

Language Notes

The name for the chemical Lime doesn't come from the fruit. It comes instead from a very old word related to the words "loam" and "slime", and to the German word for clay, "Lehm". In Old English, the word for the chemical Lime was "lïm".