Edited by carugoman - 1/21/08 at 9:43am
There are two kinds of buttermilk. One is cultured buttermilk, the thick creamy tart milk we find most often in the grocery stores. The other is 'old fashioned buttermilk' or the whey (watery yellowish liquid) that remains from milk when making cheese or churning butter. Two completely different things but both very good and useful in your kitchen (and for your chickens!).
What's left after churning butter is buttermilk. This "buttermilk" when served fresh,is more like skim milk,especially if its been sieved to remove butter flecks. If this milk is left to set on the dairy bench,at room temperature,uncovered in a wide shallow pan,for up to 18 hours,then natural cultures will sour the milk. Refrigerate as soon as possible. If you wish to make a product similar to grocery-style buttermilk,but without all the additives,emulsifiers and thickeners...there IS a WAY out. For every gallon of milk[can be whole,low-fat or skim] add one cup of dry milk powder and stir in thoroughly. Heat very slowly;raising temp by five degrees every two minutes to 180 degrees and hold this temp for 45 minutes. Cool to 78 degrees and add cultures. you can use a half-gallon of store bought buttermilk,but I don't guarantee the results. I buy active cultures from www.dairyconnection.com,costs $8.50 for a small bottle to make enough for 20-24 gallons of buttermilk;$11.50 will get you a 2x size bottle enough for 50 or so gallons of buttermilk. Buy the smaller bottle and save a quart of buttermilk to keep as active cultures for your next batch. These 'saved' cultures will keep two weeks,refrigerated. This same type of culture can be used to make sour cream,cream cheese and Quark.
Whey is the byproduct of cheese-making;not butter-making. Milk is brought to a relative high temp for a period of time;then lowered to somewhere between 76-105 degrees;cultures are added. The cultures contain "friendly" bacteria,of a known type. These friendlies create an environment that is conducive to propagating more of the same bacteria only... excluding all other types. As the cultures multiply,they consume the milk sugars[lactose] and convert them to acid[lactic]. When the proper Ph level has been reached,for that particular type of cheese that's being made,rennet is gently stirred in and the whole batch is allowed to set for a "clean break" for a period of time. This CLEAN BREAK is when the CURD[white solids] separate from the WHEY[greenish-yellow watery liquid.] The curd is the further handled to make cheese,but that's not what I'm talking about. It's the byproduct WHEY that has my attention now. If you were to take this whey and further acidulate it,say with some fresh lemon juice or citric acid[every cheese-maker has this item handy],bring the whey just to a boil and then strained though a cheesecloth[ever wonder where that name came from?] lined colander. Gather up your cloth tight tie and hang over a bowl to catch the drippings. After 3-6-8 hours depending on how much you have...I usually end up with around a pound from a four gallon batch of milk...you have Italian-style ricotta cheese;salt to taste and refrigerate. If you take the whey and add say apple cider vinegar[personal preference-white distilled will work],instead of lemon juice,bring the whey to just a boil and add the vinegar a teaspoon at a time,up to a 1/4 cup depending,until the curds start to float. Drain,strain and hang as you did for ricotta;you end up with queso blanco. Also,whey can be used as water replacement in bread baking as it adds protein to the dough or sponge. I use whey mixed with fresh fruit juice and yogurt as a "smoothie" served ice cold. And of course one could also feed the whey as is to the chickens.
All y'all take care!