Why was fermentation important in history? Where does the carbon dioxide gas come from?

Question

it's for a biology lab... we put pieces of cabbage into a sealed container of salt water, observerd pH levels, cabbage cells, and bacteria over a span of a week...

other questions include:
-why does the cabbage shirnk and lose water?
-why do you want to keep the cabbage covered by liquid at all times?
-why is Lactobacilus important in making sauerkraut?
-why do we use salt to make saukraut?


thank you so much if you can help
if you have no idea, well... i guess we have a lot in common then :P

Answer 1

Fermentation provides us with wine, bread, preserved food, like cheese, sauerkraut, soy sauce, miso, and salted fish, etc.

Glucose is broken to two pyruvate, which is in turn broken into ethanol and CO2.

The cabbage shrinks and loses water because of osmosis. Salt is added to inhibit the growth of other bacteria. That is why the cabbage should be covered by salt solution. Lactobacillus is the only bacterium that can grow in high salt. It ferments sugars and produces lactic acid. Eventually the cabbage turns sour. The acidity preserves the cabbage.