Making Yogurt – What Is Fermentation

In the case of Yogurt, fermentation is the conversion of carbohydrates (sugars) to organic acids by the action of bacteria. In yogurt made from milk, the carbohydrate is lactose (milk sugar) and the end result organic acid is lactic acid.

We have spoken before about the bacteria involved which can be one or more strains of the lactobacillus family or the streptococcus family. Now these bacteria just love sugar and they just eat it up – can’t get enough of it, and as they eat it they convert it to lactic acid which is what gives yogurt it’s tangy and slightly acidic taste.

But that is not all that happens. This feast for bacteria also coagulates or curdles the milk. What happens is that the proteins in the milk (casein) tangle together and form solid masses called curds. The remaining milk proteins form the liquid portion which is called whey. In milk roughly 80% of the milk proteins are casein which is why milk makes a lovely thick substance which we call yogurt.

For the fermentation process to occur, the milk needs to be kept at a constant temperature between 42 and 44 degrees Celsius – around 108 and 111 degrees Fahrenheit.  If the incubation temperature drops too low or goes to high, then the bacteria die and you can end up with an inferior end result.

I once had the temperature go too high while making a batch and I ended up with about 25% yogurt and 75% whey. Whey is the liquid made from milk protein that will sits on the top. Rather than waste the batch I just mixed them together and ended up with a tangy thick sort of milk and used it to make shakes.

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What is a Probiotic Culture?

So what exactly is a probiotic culture?

You will see this word probiotic many places online and the definition currently in use by the World Health Organization (WHO) is “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”.

You are the host by the way. So these are microbes or “small organisms” are alive and when you have enough of them, they give you health benefits.

The most common forms of these microorganisms are lactic acid bacteria and bifidobacteria. Lactic acid bacteria convert lactose (milk sugar) to lactic acid and if you see the words lactobacillus or acidophilus, this is what is being talked about. This is one of the most common forms of probiotics.

The health benefits that are currently being studied include managing lactose intolerance, prevention of colon cancer, lowering cholesterol levels, lowering blood pressure, improving immune system functioning, preventing infections, reducing inflammation, preventing the growth of harmful bacteria while under stress, improving the absorption of minerals, improving some of the symptoms of Irritable Bowel Syndrome (IBS) and colitis, and relieving urinary tract infections.

That is quite a list for a little microorganism and it is very exciting that something so simple can confer such enormous health benefits. As I said, these areas are being studied at the present time, but it certainly seems that eating enough quantities of these microorganisms is to our benefit.

And of course, one of the best natural sources of these critters is Yogurt – and of course I would say homemade yogurt.

So these probiotics are the good guys of intestinal flora, but there are plenty of bad guys and these little miracle workers go to work killing off all the bad bacteria in your gastrointestinal tract – and it is those bad guys that cause a lot of your belly problems. 

Now, you may have heard that taking antibiotics kills of the good bacteria in your body, and this is true and the reason why doctors won’t give you antibiotics endlessly as the bad bacteria will pretty much make sure you get sick again and stay sick. The solution to this is to eat lots of good bacteria while you are taking antibiotics and straight after you have finished to get your levels of good bacteria back up again. And, the best way to do this is to eat lots of yogurt.

Next time I will talk about the process that actually goes on that creates yogurt from milk.

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