Hi:

 

I'm in Southern California of USA. I live in Diamond Bar. It's pretty warm here.

 

I bought a 64 fluid-oz, 1.89 liter [1/2 gallon]carton of nonfat lactose-free milk and poured the milk into a plastic container with an air-tight lid. The container is now sealed-shut and in the closet of one of my bedrooms and it is room temperature in the closet. How long will it take for the bacteria in the milk to completely metabolize the milk and replace the milk with more bacteria and bacterial waste products?

 

IOW, when can I expect the milk to disappear?

 

 

Thanks,

 

Green Xenon

It shouldn't be long before you have a stinking mess but the end result would depend on the temp, the type and number of bacteria and access to oxygen. Oxygen would favor a completely different type of bacteria and possibly a faster decay rate.

It shouldn't be long before you have a stinking mess but the end result would depend on the temp, the type and number of bacteria and access to oxygen. Oxygen would favor a completely different type of bacteria and possibly a faster decay rate.

 

But the fact that there is no lactose means the milk will decay without souring. Right?

But the fact that there is no lactose means the milk will decay without souring. Right?

 

Normal anaerobic decay will probably produce acid, I'm sure it would less than sweet. to be honest you have m eon this one, I will bow to more knowledgeable people.

IOW, when can I expect the milk to disappear?

Well this cannot be easily answered as milk is a complex matrix consisting of water, proteins, sugars minerals and fat. So it is unlikely if not impossible for all components to "vanish". Now regarding the souring. In lactose free milk you still have the sugars (galactose and glucose, due to lactase treatment) as well as amino acids that can be utilized by bacteria. Depending on what pathways they use they can and will produce a number of acids (most likely commonly, acetate).

I just wonder if there's any yeast in there. Production of CO2 in a half gallon closed container of soured milk could render the room pretty near uninhabitable for ages.

Well this cannot be easily answered as milk is a complex matrix consisting of water, proteins, sugars minerals and fat. So it is unlikely if not impossible for all components to "vanish". Now regarding the souring. In lactose free milk you still have the sugars (galactose and glucose, due to lactase treatment) as well as amino acids that can be utilized by bacteria. Depending on what pathways they use they can and will produce a number of acids (most likely commonly, acetate).

 

The metals and minerals [e.g. calcium, sodium] will remain throughout. However, the organic compounds [e.g. proteins, carbohydrates] will eventually be completely degraded by the bacteria. Right?

Rarely. First, depending on the community the endproduct of organic precursors are often other organic compounds, as e.g. acetate (unless complete oxidation to CO2 is possible).

Second, in most cases metabolic byproducts create unfavorable conditions that inhibit bacterial growth before every last bit of originally present organic components have been metabolized. Essentially it depends on the total amount of organic components present in a given medium- if the amount is very low then total metabolization is more likely.