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Wednesday, March 11, 2009

Goat milk whey lactose levels

I just measured the sugar content of the whey being expelled from a two gallon goat loaf that is currently fermenting (heh, goat loaf), and the reading came out to 6brix. That means that whey from coagulated goat (heh, coagulated goat) has 10-15% less lactose it looks like than raw moocow milk.

From Wikipedia, "In use, a sample is placed between a measuring prism and a small cover plate. Light traveling through the sample is either passed through to the reticle or totally internally reflected. The net effect is that a shadow line forms between the illuminated area and the dark area. It is where this shadow line crosses the scale that a reading is taken."

The refractometer I use looks similar to the one pictured on the right, but is used to measure sugar levels, in this case lactose. It is highly likely that I'm misinterpreting some crucial point here, but through tasting the samples and measuring them I am pretty confident that there is indeed a lower amount of lactose in goat milk.

The reason why this is important is fundamental--the more lactose (i.e., the sweeter the milk), the higher the potential acidification (sharpness), which directly affects flavor and texture. That is why washed cheeses are usually milder, since the washing removes lactose, thus removing the potential for excessive acidification. Over acidified curds also can cause corky textures which are generally considered defects.


  1. That's really interesting; I'm lactose intolerant and I can tell you goat cheeses bar none give me a lot more grief than most cow cheeses. Why would that be?

  2. Ah, I actually know the answer to that. Moo cow cheese is usually left to ferment much, much longer than goat cheese. Most goat cheese is eaten rather young--chevre for instance is eaten almost immediately after it has been made.

    This means that there is a ton of lactose left in goat cheese (since it is usually young). Moo cow on the other hand, especially sharp stuff, has been left to ferment for months or years. 18 month cheddar/colby/gouda has almost no residual lactose, since it has been consumed by the little bacteria guys.

  3. Ah ha, that makes sense. Definitely explains why things like parmesan and sharp cheddar don't bother me as much as even mozzarella or other, fresher cow cheeses. Velly smart, Jeremy.


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