Posted on: 18-08-05 09:58:25
Hi Pratickm,
You got it 
However, there are further niceties involved, since we are on Rasoi topic.
1. When we use lukewarm milk and add a half teaspoonful curd (culture) from curd or plain yoghurt and keep it undisturbed in a warm place, in about 4 to 8 hours the culture flourishes, in the process releasing lactic acid. As process is slow curdling is slow and it sets as firm dahi/curd. It gives typical flavour depending upon quality of dahi/curd used as culture. Some people use buttermilk as culture when they are finished with curd at home.
2. When you are boiling milk and add something to lower pH, like
a. Fresh Lemon/lime juice
b. Tatri (tartaric acid) Edible Grade
c. Citric Acid (from Nimbu again) Edible Grade
d. Acetic Acid (not preferred by many due to its smell) Edible Grade
paneer seperates instantly from whey, but it is sterile and there is no culture. Flavour, if any, comes from additive. You can strain it in a clean muslin/cotton cloth. If you want it soft, you can use it as it is. If you want it firm, tie up and hang cloth overnight, whey will drain away and next day you can cut blocks out of paneer.
3. <Or simply leave the milk out for a couple of days and it will curdle automatically - assuming it is not "sterile" milk.>
Unfortunately this not an option, as it is an uncontrolled reaction. We do not know which bacteria are multiplying in milk. It may lead to deadly food poisoning if consumed. Best thrown away! 
Hi Azazf,
Citric acid and Tartaric Acid are different food additives but used for almost same purpose. They look the same. Making paneer or adding for sour taste is very minor use.
Essentially they are used as preservatives to lower the pH. Generally used in Jams, Squash, Jellies,Preserves where you do not want to use common salt for preservation. Lower pH is unfriendly environment for bacteria/fungus to grow.
Common salt in Achar acts in different way. It sucks out water from bacteria/fungus and kills them.
Quote:The kind of bacteria you would get depends on what the quality of the milk was - which is why I said "assuming it is not 'sterile' milk".
Orginally posted by LD
3. <Or simply leave the milk out for a couple of days and it will curdle automatically - assuming it is not "sterile" milk.>
Unfortunately this not an option, as it is an uncontrolled reaction. We do not know which bacteria are multiplying in milk. It may lead to deadly food poisoning if consumed. Best thrown away!
Commercial suppliers of milk believe that they can make it sterile by UHT pasteurization.
However, all that it achieves is destroying the good bacteria, thereby making it easier for the dirty bacteria to grow because the good guys aren't there to stop them.
Which is why people do get food poisoning even from UHT pasteurized milk.
When using pasteurized milk, it is often a better idea to use a culture (such as yogurt or kefir) to ensure that you get the right kind of bacteria.
As for UHT milk, I have noticed that it often cannot support cultures because it is too far gone.
The only way to curdle such milk is to use lime juice or the pH lowering chemical compounds.
As a side note, it is quite common in traditional communities to curdle raw milk by allowing it to separate naturally.
I have seen receipes for making yogurt and buttermilk out of raw milk.
The natural bacteria of milk must be ensuring that the dirty bacteria cannot take hold.
I believe milk with Brix rating of 16 or higher is right up there in terms of quality and can be relied upon to separate naturally.
Unfortunately, commercial suppliers do not provide the Brix rating of milk on the package.
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"Mah deah, there is much more money to be made in the destruction of civilization than in building it up."
-- Rhett Butler in "Gone with the Wind"
Hi Pratickm,
<As a side note, it is quite common in traditional communities to curdle raw milk by allowing it to separate naturally>
Yes you are right.
At times of Changez Khan (Genghis Khan) mongols used to use mare's milk and stored it in leather pouches. Milk would curdle and dry out, to be eaten on the move. As they were always on war, invading across half the world, it was a very practical strategy/recipe. (Incidentally their pecking order was - young warriors, young females, then older able bodied people and then kids.Too bad if little was left for kids.)
My grandmother used to fill warm milk in cleanly washed "kadhaoni" or the wide mouth earthern pitcher at about 8.00PM in night. No culture. It would set into nice curd and she would churn it at 3.30 AM next morning to get the butter out. Buttermilk she would distribute free to anyone in village who came asking for it. ( Incidentally she got up at 3.00 AM and her work would continue till about 9.00PM x 365 days). Even hard work fell ligthly on her shoulders and we always saw her smiling and laughing!
Try telling your wife to get up at 5-am in the morning and you wont get food for a few days 
. Times have changed drastically
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"Progress comes from deviation".
On a side note if anybody finds my comments or posts offensive or irritating please ignore it and if that still bothers you; please write to me and I will demonstrate.
Quote:Very interesting bit of information, LD.
Originally posted by LD
At times of Changez Khan (Genghis Khan) mongols used to use mare's milk and stored it in leather pouches. Milk would curdle and dry out, to be eaten on the move. As they were always on war, invading across half the world, it was a very practical strategy/recipe. (Incidentally their pecking order was - young warriors, young females, then older able bodied people and then kids.Too bad if little was left for kids.)
For two reasons - (1) cow's milk was not really that common in traditional communities. It became common because of the large-scale commercialization of milk production and distribution.
Incidentally, this also brought about pasteurization and homogenization of milk, both of which were unheard of during traditional times (and in isolated, non-industrialized communities even today).
Also, different traditional communities prefer different kinds of milk. Other than mare's milk, I have also read about seal's milk and deer milk being used extensively.
(2) Also interesting is the fact that kids were not fed that much milk in traditional communities, at least not uncultured/unfermented milk.
I think the commercialization of milk has brought about this change as well.
The history of milk production and distribution reflects human progress very well.
Have you read "The Untold Story of Milk"?
http://www.amazon.com/exec/obidos/tg/detail/-/0967089743/qid=1124481362/sr=2-1/ref=pd_bbs_b_2_1/102-7046790-6191314?v=glance&s=books
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"Mah deah, there is much more money to be made in the destruction of civilization than in building it up."
-- Rhett Butler in "Gone with the Wind"
