Buttermilk
<p ><b>Buttermilk</b> refers to a number of dairy drinks. Originally, buttermilk was the liquid left behind after churning <a href="http://en.wikipedia.org/wiki/Butter" title="Butter" >butter</a> out of <a href="http://en.wikipedia.org/wiki/Cream" title="Cream" >cream</a>. This type of buttermilk is known as <i>traditional buttermilk.</i></p>
<p>
The term <i>buttermilk</i> also refers to a range of fermented milk drinks, common in warm climates (e.g., Middle East, Pakistan, India, and the Southern United States) where unrefrigerated fresh milk otherwise sours quickly,<sup id="cite_ref-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Buttermilk#cite_note-0" >[1]</a></sup> as well as in colder climates such as Germany, Poland, Scandinavia and the Netherlands. </p>
<p>
This <a href="http://en.wikipedia.org/wiki/Fermented_dairy_product" title="Fermented dairy product" class="mw-redirect" >fermented dairy product</a> known as <i>cultured buttermilk</i> is produced from <a href="http://en.wikipedia.org/wiki/Cow%27s_milk" title="Cow's milk" class="mw-redirect" >cow's milk</a> and has a characteristically sour taste caused by <a href="http://en.wikipedia.org/wiki/Lactic_acid_bacteria" title="Lactic acid bacteria" >lactic acid bacteria</a>. This variant is made using one of two species of bacteria—either <i><a href="http://en.wikipedia.org/wiki/Streptococcus_lactis" title="Streptococcus lactis" class="mw-redirect" >Streptococcus lactis</a></i> or <i><a href="http://en.wikipedia.org/wiki/Lactobacillus_bulgaricus" title="Lactobacillus bulgaricus" class="mw-redirect" >Lactobacillus bulgaricus</a></i>, which creates more tartness. Buttermilk made with the latter is called <i><a href="http://en.wikipedia.org/wiki/Bulgarian_people" title="Bulgarian people" class="mw-redirect" >Bulgarian</a> buttermilk</i>.</p>
<p>
The tartness of buttermilk is due to acid in the milk. The increased <a href="http://en.wikipedia.org/wiki/Acidity" title="Acidity" class="mw-redirect" >acidity</a> is primarily due to <a href="http://en.wikipedia.org/wiki/Lactic_acid" title="Lactic acid" >lactic acid</a> produced by lactic acid bacteria while <a href="http://en.wikipedia.org/wiki/Fermentation_(biochemistry)" title="Fermentation (biochemistry)" >fermenting</a> <a href="http://en.wikipedia.org/wiki/Lactose" title="Lactose" >lactose</a>, the primary sugar in milk. As the bacteria produces lactic acid, the <a href="http://en.wikipedia.org/wiki/PH" title="PH" >pH</a> of the
milk decreases and <a href="http://en.wikipedia.org/wiki/Casein" title="Casein" >casein</a>, the primary milk protein, precipitates, causing the <a href="http://en.wikipedia.org/wiki/Curdling" title="Curdling" >curdling</a> or <a href="http://en.wikipedia.org/wiki/Clabber_(food)" title="Clabber (food)" >clabbering</a> of milk. This process
makes buttermilk thicker than plain milk. While both traditional and cultured buttermilk contain lactic acid, traditional buttermilk tends to be less viscous, whereas cultured buttermilk is more viscous.<sup id="cite_ref-Fankhause_1-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Buttermilk#cite_note-Fankhause-1" >[2]</a></sup></p>
<p>
Buttermilk is usually drunk straight, but it can also be used in cooking. <a href="http://en.wikipedia.org/wiki/Soda_bread" title="Soda bread" >Soda bread</a> is a bread where the buttermilk acidifies the rising agent, <a href="http://en.wikipedia.org/wiki/Sodium_bicarbonate" title="Sodium bicarbonate" >sodium bicarbonate</a>, to produce <a href="http://en.wikipedia.org/wiki/Carbon_dioxide" title="Carbon dioxide" >carbon dioxide</a>.
</p>
<table class="infobox" >
<caption >Buttermilk, low fat</caption>
<tbody>
<tr>
<th colspan="2" >Nutritional value per 100 g (3.5 oz)</th>
</tr>
<tr >
<th ><a href="http://en.wikipedia.org/wiki/Food_energy" title="Food energy" >Energy</a></th>
<td >169 kJ (40 kcal)</td>
</tr>
<tr>
<th ><a href="http://en.wikipedia.org/wiki/Carbohydrate" title="Carbohydrate" >Carbohydrates</a></th>
<td >4.8 g</td>
</tr>
<tr>
<th ><a href="http://en.wikipedia.org/wiki/Fat" title="Fat" >Fat</a></th>
<td >0.9 g</td>
</tr>
<tr>
<th ><a href="http://en.wikipedia.org/wiki/Protein_(nutrient)" title="Protein (nutrient)" >Protein</a></th>
<td >3.3 g</td>
</tr>
<tr>
<td ><a href="http://en.wikipedia.org/wiki/Calcium#Nutrition" title="Calcium" >Calcium</a></td>
<td >116 mg (12%)</td>
</tr>
<tr >
<td colspan="2" >Percentages are relative to
<a href="http://en.wikipedia.org/wiki/Dietary_Reference_Intake" title="Dietary Reference Intake" >US recommendations</a> for adults.</td>
</tr>
</tbody></table>
<p > </p>