What is the best grade of plastic for brewing and storing alcohol (up to about 15%)?
Basically as the title suggests, I’m in a rural part of Tanzania with no access to glass but I do have access to some food grade plastics.
There is nothing better than glass from a standpoint of oxygen ingress. The next best choice would be PET, followed by polyethylene and polypropylene. With PE and PP the density of the material (which varies) is more important than the material itself. Go for HDPE and HDPP if you can get it, and avoid LDPE and LDPP.
Polypropylene is commonly used for brewing buckets but is not so good for containing pressurised/fizzy drinks. PET is most commonly used for fizzy drinks bottles.
PET soda bottles are good for storing beer for a while - for example 6 months. Over time the CO2 gas will slowly diffuse through the bottle walls and gradually depressurise the beer. Which means beer cannot be left to mature/age for any great time and remain "fizzy". However some people prefer less fizzy beer so it depends on one's taste....
If storing still wine then food grade PET containers are acceptable. But again it is worth remembering oxygen can diffuse inward as much as CO2 can diffuse outward. The oxygen may affect the flavour of the brew over an extended time (eg 1-2 years).
If one is just storing distilling mash or "banana beer" for a short while then almost any food grade plastic container will do
I have stored wine and beer in PET soda bottles and it worked fine for me. Also, they can handle high pressures, so if you have excess refermentation in the bottle then you don't split the bottles.