If already when we started the section of microbe of the week we tell you about the yeast of the beer, we can not ignore the bacteria that makes yogurt.
And it is that although beer gives us very happy, yogurt is still a very important food in our days, so this bacteria also deserves a place in the section.
Is about Streptococcus thermophilus, a bacterium that; beside Lactobacillus bulgaricus, transforms milk into one of the most widespread desserts throughout the world, demonstrating that, as in so many other cases, the metabolism of other living beings can be coupled to obtain great benefits and products for the human species.
What do we know about Streptococcus thermophilus?
As I was saying, Streptococcus thermophilus is a gram positive bacteria facultative anaerobia. The latter means that it can develop both in presence and in absence of oxygen, so they can carry out both conventional breathing and fermentation processes, in which the making yogurt.
Due to the type of fermentation it performs, it is considered a lactic acid bacteria and for its ability to be part of the bacterial flora of the stomach is found within the group of probiotic bacteria.
How does the fermentation of milk take place to give rise to yogurt?
As I was saying, in absence of oxygen These bacteria need to obtain energy through a fermentation mechanism, known as lactic acid fermentation.
This process consists of the transformation of milk sugars in lactic acid. Although the end forbacterium in this case it is the obtaining energy, the result obtained has been used by humans for thousands of years, which thanks to them we can take food like elyogur or kfir.
What are the characteristics of the yogurt?
For starters, one of the most relevant characteristics of yogurt is its texturemuch thicker than the milk. This is because the production of the acid gives rise to a pH drop which causes a change in protein structure, which precipitate forming a kind of gel.
This acidificationIt is also very beneficial, because it gives rise to the inhibition of the growth of other microorganisms They could be harmful if consumed.
To check it, you can add lemon juice to a glass of milk and you will see how it is cut giving rise to that makeover.
On the other hand, the taste and the aroma are due to both lactic acid like other secondary products obtained in the reaction, such as acetaldehyde and diacetyl.
How can we make yogurt at home?
The yogurt making process is so simple that we can do it ourselves using only a liter of milk and a yogurt. But why do we use yogurt to make yogurt? As I was saying, for fermentation to take place, the action of our bacteria today, among others, is necessary, but where do we get it from? The bacteria They are not something that you can ask for a quarter in the supermarket, but I do know that we have a huge reservoir of them in stores: yogurts.
The microorganisms that were used to make it are still there, so when you mix the yogurt with milk again, the reaction.
Of course, these bacteria do not work in any way, but a temperature of about 43C, which can be achieved by providing heat through a blanketfor example or using a yogurt maker, which will give the mixture the just temperature so that the microbes work properly and give us a few jars of yogurt a few hours later.
As you can see, the production of yogurt is a simple but fascinating procedure that we can even do ourselves at home. And all thanks to our microbe today!