Looking for food industry experience with Inert Gas Generators

Hello, I am looking for food industry experience with the use of inert gas generators (natural gas combustion) to produce packaging gas (approx. 12% CO2). These systems were popular in the 1980s and 1990s and as I understand were used as the first step in the carbonation process at one time. They are seldom used now so I may be looking for historical expertise, however, a few systems are still in use in the food industry.

I would like to know what kind of filtration was used by food manufacturers who had these systems in their manufacturing facilties to remove possible natural gas hydrocarbon/combusion contaminants from the packaging gas.

Thanks