DAIRY TECHNOLOGY: FERMENTED MILK
Diagram
True buttermilk and cultured buttermilk side by side
True buttermilk
The liquid left when butter is churned: thin, low in fat, and mildly sour.
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Cultured buttermilk
Skim milk fermented with lactic cultures: thick, tangy, and made on purpose.
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The core difference
Origin. True buttermilk is a by-product of churning; cultured buttermilk is a fermented milk made to order.
Figure 1: True buttermilk compared with cultured buttermilk. Drawn in our own style from Anne Mendelson, Milk: The Surprising Story of Milk Through the Ages, Knopf, 2008, ch. BUTTER AND TRUE BUTTERMILK, p. 229.
Introduction
True buttermilk and cultured buttermilk share a name and a tang, but they are made in opposite ways. One is what is left after butter is made; the other is a milk fermented on purpose.
The core difference is origin. True buttermilk is the liquid that drains from the churn when butter forms, and it is thin and low in fat. Cultured buttermilk is skim milk with lactic cultures added and left to ferment until it thickens, and it is the thick tangy buttermilk sold in cartons today.
Quick comparison
Table 1: True Buttermilk compared with Cultured Buttermilk
| Aspect | True Buttermilk | Cultured Buttermilk |
|---|---|---|
| Origin | Liquid left from churning butter | Skim milk fermented with lactic cultures |
| Fat content | Very low, under 1 percent fat | Very low, under 1 percent fat, made from skim milk |
| Texture | Thin, watery, pours easily | Thick, creamy, coats a spoon |
| Flavour | Mildly sour, fresh, buttery note | Sharp and tangy, clean acid flavour |
| Acidity | Mild, depends on the cream | Higher, set by the culture to about pH 4.5 |
| Cultures | Whatever microbes were in the cream | Defined lactic cultures, often with aroma makers |
| Availability | Rare today, only where butter is churned | Sold everywhere in cartons |
| Shelf life | A day or two, spoils fast | About 1 to 2 weeks when kept cold |
| Main use | Drinking on the farm, baking, feeding animals | Drinking, baking, pancakes, dressings and marinades |
| Baking role | Adds moisture and a mild tang | Acid reacts with baking soda to lift the batter |
Scientific explanation
Definition
True buttermilk is the liquid that remains after cream is churned into butter. It is the watery part of the cream, with most of the fat removed as butter.
Cultured buttermilk is skim milk fermented with lactic acid bacteria until it thickens and turns tangy. It is made to imitate the flavour of true buttermilk.
Working principle
Churning breaks the fat globule membranes, so the fat joins into butter and the liquid that is left is the buttermilk. It holds the water, protein, lactose and minerals of the cream, with only a little fat left.
Cultured buttermilk works by fermentation: the cultures eat lactose, make lactic acid, and the acid sets the casein into a thick gel. The aroma makers in the culture also make diacetyl, which gives the buttery smell.
Apparatus
A churn for true buttermilk, and a strainer to drain it from the butter.
For cultured buttermilk, a fermentation tank held warm, a starter culture, and a filler for the cartons.
Measurement procedure
For true buttermilk, churn the cream until butter grains form, then drain off the liquid. That liquid is the true buttermilk.
For cultured buttermilk, pasteurize skim milk, cool it, add the lactic culture, hold it warm until the pH reaches about 4.5 and the milk thickens, then cool it at once and pack it.
Factors affecting readings
The cream decides true buttermilk: sweet cream gives a mild buttermilk, soured cream gives a tangier one.
For cultured buttermilk, the culture, the temperature and the time decide the tang: warmer and longer gives more acid. The milk must be skim milk, or the product will be too rich.
Formulas and calculations
The books give no formula for this pair. The acidity is measured by titration and given as percent lactic acid.
Worked example of the titration: Titratable acidity (percent lactic acid) = (Volume of alkali used x Normality x 0.09 x 100) divided by the weight of the sample. Cultured buttermilk usually reads higher than true buttermilk by this test.
Industrial applications
- True buttermilk: drinking on the farm and in traditional cooking where butter is churned.
- True buttermilk: baking and animal feed, where the liquid is used rather than thrown away.
- Cultured buttermilk: pancakes, soda bread and cakes, where its acid lifts the batter with baking soda.
- Cultured buttermilk: salad dressings, marinades and fried chicken, where its tang suits the dish.
- Both: a low-fat drink and a baking ingredient.
Advantages and limitations
- True buttermilk advantage: a natural by-product, low in fat, with a fresh mild flavour.
- True buttermilk limitation: rare today, thin, and spoils within a day or two.
- Cultured buttermilk advantage: thick, tangy and consistent, sold everywhere with a good shelf life.
- Cultured buttermilk limitation: it is a made product, not the churn by-product, and its flavour is set by the culture used.
FAQ
Is the buttermilk in the shop real buttermilk?
It is cultured buttermilk, not true buttermilk. It is skim milk fermented with cultures to imitate the tang of the churn by-product.
What is true buttermilk then?
The thin liquid left in the churn after butter is made. It is rare in shops because few places churn butter by hand now.
Why is cultured buttermilk thick but true buttermilk thin?
Cultured buttermilk is fermented until its protein sets into a gel, which thickens it. True buttermilk is just the liquid left from the cream, and nothing has set it.
Can I use cultured buttermilk in baking?
Yes. Its acid reacts with baking soda to lift pancakes, soda bread and cakes, and its tang suits the flavour.
Is buttermilk high in fat?
No. Both kinds are low in fat, under 1 percent, because the fat has gone into the butter or was removed as skim milk.
References and further reading
- Anne Mendelson, Milk: The Surprising Story of Milk Through the Ages, Knopf, 2008, ch. BUTTER AND TRUE BUTTERMILK, p. 229 (Google Books page read)
- FTN books on disk: Fat Rich Dairy Products Technology, Starter Cultures and Fermented Milk Products (agrimoon dairy series).
