"Scott" > wrote in message
...
> In article >,
> Becca > wrote:
>
>> 1 cup milk and one tablespoon vinegar.
>
> That's for soured milk, which is not the same as buttermilk. As the King
> Arthur Flour Baker's Companion notes, buttermilk is "thinner than sour
> cream and thicker than sour milk." The soured milk substitute above will
> give you the desired reaction with baking soda, if that's the goal, but
> it won't provide the same mouthfeel.
>
> --
> to respond (OT only), change "spamless.invalid" to "optonline.net"
>
> <http://www.thecoffeefaq.com/>

Sour milk also does not provide the same chemical properties as cultured or
even better, dried buttermilk.
"The product sold today in the dairy case is labeled "cultured" because a
specially prepared culture of beneficial bacteria, developed under
laboratory conditions, is added to skim milk to produce the acidity, body,
flavor, and aroma so characteristic of old fashioned "soured" buttermilk.
When added to skim milk, these bacteria multiply and convert some of the
milk sugar (lactose) to lactic acid. The lactic acid gives the cultured milk
its tart flavor. The thickness is the result of the bacterial action of the
milk protein.

Although fluid "Cultured Buttermilk" is an excellent beverage, providing
many nutritional benefits, it does not have the same chemical properties as
real churned buttermilk.

Chemical Composition is the Key
The chemical composition of churned buttermilk holds the key to its
desirable baking characteristics.

The suggested structure of a fat globule membrane is such that fat droplets
in milk are prevented from coalescing by a thin coating of emulsifier (a few
millimicrons thick) around the fat globules at the liquid/fat interface.

Four types of phospholipids participate in the formation of the fat globule
membrane. It appears that near the periphery of the fat globules there are
segregated high-melting triglycerides which join the non-polar prongs of the
phospholipid molecules (molecules of Vitamin A and cholesterol are
interspersed among the phospholipid molecules).

Churned buttermilk contains emulsifiers
When whole milk stands, the many clusters of emulsified fat droplets, being
lighter, rise to the top of the milk in a process called "creaming". Butter
can be extracted from cream by churning. When the cream is agitated in a
butter churn, the membranes around the fat globules are disrupted. The cream
then separates into two pieces; the butterfat and the fluid phase. The
phospholipids, protein and bound water that compose the fat globule membrane
separate from the fat globule. This allows the butterfat to precipitate out
in the form of butter. The phospholipids, meanwhile, remain in the fluid
phase. The fluid that remains, after all the butterfat has been removed as
butter, is similar to skim milk except it contains the phospholipids and
proteins from the fat globule membranes. These phospholipids are natural
emulsifiers!

The value of real buttermilk in baking
When real buttermilk is used in a recipe, the presence of these emulsifiers
results in finer dispersing of the shortening throughout the batter. The
smaller air cells which form in the presence of the emulsifier make the
grain of baked goods finer, the volume and texture superior. This is by far
the most important advantage of using real buttermilk for cooking and
baking.

Since most recipes that call for buttermilk also call for baking soda, it is
essential that there is an acidic ingredient in the recipe to react with the
baking soda. This is why it is important for buttermilk (either fluid or
dry) to be "cultured". The acidic nature of "churned" buttermilk contributes
to the leavening process which is necessary for successful baking.

The "culturing" process also gives buttermilk (either fluid or dry) its
distinct, acidic flavor. However, this flavor is often disguised by other
ingredients in the recipe.

Many cookbooks suggest that buttermilk can be substituted with milk that has
been "soured" by the addition of lemon juice or vinegar. This substitution
is not as effective in the baking process as either fluid "Cultured
Buttermilk" or real churned buttermilk."

SACO FOODS excerpt