July 8, 2012
Hi all! Since being back at Windward once more, I've been busy helping set up for the Village Helix, which went really really well. In some of the empty spaces, I've been experimenting with food. (Of course!)
More specifically, yogurt! I wanted to use some of Becca's milk, which doesn't get used very quickly, to make something people would consume. The alchemy of milk follows...
- 1. Milked Becca.
- 2. Filtered the milk to take out any straw that might have fallen in.
- 3. Heated the milk to just below boiling, when it began to froth.
- 4. Stirred in but a tablespoon of bacterial culture from a cup of store-bought yogurt with live cultures.
- 5. Put the inoculated milk in the warmerator* for about 24 hours. Done!
Here's what I discovered:
- 1. No need to be sterile. Just use clean non-metal containers and utensils.
- 2. Adding more culture does not result in making yogurt faster. Bacteria don't like being crowded, and yogurt will come out thinner than usual.
- 3. If all you have is flavored yogurt for the starter, use it anyway. Turns out that the flavoring does not affect the "yogurtification" process. When I used strawberry yogurt, the strawberry bits settled to the bottom, and the yogurt came out plain.
- 4. If I strain the yogurt through a very-small-pored cloth overnight and let the whey drain out, I get sour cream in the morning!
And here's the science behind the deliciousness:
Certain species of bacteria are responsible for turning milk into yogurt, giving it the slightly acidic taste of "yogurtiness". As the bacteria feed on the lactose (a sugar) in milk, they produce lactic acid, an acidic waste that cause the proteins in the milk to tangle into a solid mass and result in clotting the milk. The acidic environment serves to prevent other bacteria from moving in, preventing the yogurt-to-be from spoiling. And, in the process of altering the proteins, these bacteria also give yogurt its distinctive flavor.
While many different kinds of Lactobacillus bacteria may be used to make yogurt, the most common are: Lactobacillus bulgaricus, Lactobacillus acidophilus, as well as Streptococcus salivarius and Streptococcus thermophilus. They can be found in a cup of store-bought yogurt that describes the "live active cultures" contained within.
So, for people who have trouble digesting the lactose, yogurt is a great way to get calcium into the body. Yogurt also contains protein and fat, the amounts of which depend on how the animal producing the milk is treated. The lower pH of yogurt (more acidic) compared to milk may also aid in digestion. Experiment on yourself!
Want thicker yogurt? Try science!
- 1. Keep it warm. While incubating, try to have the surrounding temperature right around 105 deg F. You can use a warm-water bath in a cooler, an oven (turned off) but with the light on to heat it just a little, or get a dragon to keep it at temperature with little flames. The thermophilic (heat-loving) bacteria don't grow well below 98 deg F.
- 2. Heat the milk to just below boiling before adding the starter to begin to denature the proteins in the milk. Remember to cool the milk to a little warmer than body temperature before adding the starter, so that you don't scald and kill the bacteria. Even though these bacteria are themophilic, they cannot withstand temperatures much in excess of 130 deg F.
- 3. Add dry milk before incubating (although I'd rather not put anything processed into Becca's milk).
- 4. Strain out the whey. This removes some nutrients from your milk, but does make it thicker. Use the whey to cook pasta or feed your compost, pigs, chickens, or children.
- 5. Leave it alone. Don't bother it unless you want a spoonful :) This allows the whey to remain incorporated into the milk.