Yeast - Home Made

Ingredients

Quantity	Measure	Ingredients	Description:
1	Teacup	Milk	Boil one teacup of milk
1/2	Teacup	Water	Boil one teacup of milk
4	Medium	Potatoes	Wash and cut
200	Grams	Dhal, Chana	add it to the diluted milk,
50	Grams	Yeast - dry	add it to the diluted milk,

Method

Boil one teacup of milk with 1/2 cup of water for 5 minutes. Keep down.   Wash and cut the four potatoes into slices, without peeling them, and add it to the diluted milk, and to it also add 200 grams of chana dhal and a little yeast.

Pour the liquid in a jar, and cover the top with a cloth.   Keep in the warmest place in the house, and after 12 hours, the liquid should froth.   If not, place it near fire for half an hour till it froths.

When the liquid froths, it has fermented and is ready.   Strain this liquid and store it in a glass bottle.

This can be used instead of toddy, for fermenting any dough.

http://en.wikipedia.org/wiki/Yeast

Yeasts are generally grown in the laboratory on solid growth media or in liquid broths. Common media used for the cultivation of yeasts include; potato dextrose agar (PDA) or potato dextrose broth, Wallerstein Laboratories nutrient (WLN) agar, yeast peptone dextrose agar (YPD), and yeast mould agar or broth (YM). Homebrewers who cultivate yeast frequently use dried malt extract (DME) and agar as a solid growth medium. The antibiotic cycloheximide is sometimes added to yeast growth media to inhibit the growth of Saccharomyces yeasts and select for wild/indigenous yeast species. This will change the yeast process.

The appearance of a white thready yeast commonly known as kahm yeast is often a byproduct of the lactofermentation (or pickling) of certain vegetables, usually the result of exposure to air. Although harmless it can give pickled vegetables a bad flavour and so must be removed regularly during fermentation.

Baker's yeast is available in a number of different forms. Though each version has certain advantages over the others, the choice of which form to use is largely a question of the requirements of the recipe at hand and the training of the cook preparing it. With occasional allowances for liquid content and temperature, the different forms of commercial yeast are generally considered interchangeable.

Compressed yeast is essentially cream yeast with most of the liquid removed. It is best known in the form of cake yeast, which is essentially a soft solid, beige in color, but is also available in crumbled form for bulk usage. It is highly perishable; though formerly widely available for the consumer market, it has become less common in supermarkets in some countries due to its poor keeping properties, having been superseded in some such markets by active dry and instant yeast. It is still widely available for commercial use, and is somewhat more tolerant of low temperatures than other forms of commercial yeast; however, even there, instant yeast has made significant market inroads.
Active dry yeast is the form of yeast most commonly available to noncommercial bakers in the United States, as well as the yeast of choice for situations where long travel or uncontrolled storage conditions are likely. It consists of coarse oblong granules of yeast, with live yeast cells encapsulated in a thick jacket of dry, dead cells with some growth medium. Under most conditions, active dry yeast must be proofed or rehydrated first. It can be stored at room temperature for a year, or frozen for more than a decade, which means that it has better keeping qualities than other forms, but it is generally considered more sensitive than other forms to thermal shock when actually used in recipes.
Instant yeast appears similar to active dry yeast, but has smaller granules with substantially higher percentages of live cells. It is more perishable than active dry yeast, but also does not require rehydration, and can usually be added directly to all but the driest doughs. Instant yeast generally has a small amount of ascorbic acid added as a preservative. Some producers provide two or more forms of instant yeast in their product portfolio; for example, LeSaffre's "SAF Instant Gold" is designed specifically for doughs with high sugar contents.
Rapid-rise yeast is a variety of yeast (usually a form of instant yeast) designed to provide greater carbon dioxide output to allow faster rising at the expense of shortened fermentation times. There is considerable debate as to the value of such a product; while most baking experts believe it reduces the flavor potential of the finished product, Cook's Illustrated magazine, among others, feels that at least for direct-rise recipes, it makes little difference. Rapid-rise yeast is often marketed specifically for use in bread machines.

For most commercial uses, yeast of any form is packaged in bulk (blocks or freezer bags for fresh yeast; vacuum-packed brick bags for dry or instant); however, yeast for home use is often packaged in pre-measured doses, either small squares for compressed yeast or sealed packets for dry or instant. For active dry and instant yeast, a single dose (reckoned for the average bread recipe of between 500 g and 1000 g of dough) is generally about 2.5 tsp (~12 mL) or about 7 g (1/4 ounce), though comparatively lesser amounts are used when the yeast is used in a pre-ferment.