We have used hot air and hot water treatments to kill fungi on tomatoes, melons and peppers.

I have done some work with garlic, but have only sporadically seen this physiological disorder.  Plant pathologists confirm that it is not microbial in origin.   Attached is a summar

The thick plastic bag is likely HDPE (high density polyethylene) and is virtually impermeable.  Therefore there will be no gas exchange once the bag is sealed.
 

The thick plastic bag is likely HDPE (high density polyethylene) and is virtually impermeable.  Therefore there will be no gas exchange once the bag is sealed.
 

The green color formation in garlic is related to the acidity of the garlic.