I hate buying all of those plastic jugs too, I try to me pretty plastic free at home.
I’m looking for any experience on making ACV in a 55 gallon drum. I’m contemplating making a fabric bag to fill with the fruit pieces that can be pulled out once the vinegar is done and also putting a quality, metal tap at the bottom so we can just use the vinegar straight from the barrel we make it in?
I have a guy that sells all kinds of barrels. Should I choose a plastic or food-grade metal one? Could I make ACV with pears instead of apples? Our neighbor has a huge pear tree in his cow pasture that we pick from each year.
I ferment kombucha, kraut, kimchi, yogurt, and hot sauce regularly so I am slightly experienced in fermenting foods- that being said, any experience of tips would be really appreciated!
You do not want to use metal drums, the process of making vinegar is two part and the fermentation side (step one) will produce enough alcohol to eat through any lining material considered food grade.
Distillers use copper or stainless steel because these hold up to the corrosive alcohol far better than anything else.
Mashes are done in food grade plastic barrels (the shiners method) and these are the cheapest, easiest containers to get your hands on.
When you make vinegar you make your mash, then strain out all the fruit and or grain before you ferment (this is called the Wort) if you wait to do this until after the fermentation you will have cloudy wine that then needs two extra steps to clear your liquid.
Other than that it sounds to me like you have a good handle on the process.
I have restaurants and we make vinegars (not at the speed or volume that we use, because just like you we go through a shit ton of vinegar), but I have learned quite a bit over the years.
You can make vinegar out of anything alcoholic. Distilled white vinegar is made out of the cheapest shit you can imagine. Corn, rice, or sugar pureed into clean water are all acceptable substrates for innoculation with an alcohol producing strain of yeast, then vinegar.
What Red Hawk means by two stage is that first you have an alcoholic fermentation, carried out by yeast, then you have a second wave of digestion by an acetobacter, which we like to call a vinegar mother to sound fancy.
It is certainly true that this process needs no help from you-- a piece of fruit can hypothetically fall into an ideal puddle during a rainstorm, and God will take care of the rest. Biologists were not wrong in the theory that alcoholic fermentation predates mankind. But we can ensure better results by cranking down the nuts on this naturally occurring phenomenon.
Let's reverse calculate. Alcohol is the food in the second stage: an acetobacter turns alcohol into acid and other flavor and odor characteristics: polyphenols and flavor esters, what wine geeks describe when they talk about chocolate and cherries and toast and stuff like that when they taste the Bordeaux. But never mind all that shmiggle-shmaggle. We need alcohol.
While there are zillions of strains of yeast in the open air, they are in low concentration and low competition, therefore unlikely to produce the characteristics that you desire in one shot (although possible). First responder yeast tend to be weak, and kill themselves out at a low alcohol concentration, like 1-3%. Low alcohol content is not much food and will yield weak vinegar.
Starting with strong commercial yeast, like champagne yeast, should yield a higher alcohol content, up to 17 or even 20% if your sugar and temperature and other factors are optimum.
Then, the same holds true of an acetobacter. Sure, if you hang out long enough God will send you one, or 37-- but you really don't know what you're going to get, and I wouldn't bet the farm on the first one going gangbusters right out the gate. Best bet is to make a friend who already has a proven vinegar mother going. If this is already a hobby they have, cutting a chunk of the vinegar mother is not only free, but kind of a bonding moment.
(They are literally, quite literally, handing you their culture.)
The rest is just a waiting game: time, temperature, voracity of the organism, yada yada.
Again Redhawk is right about stainless--pro stuff, awesome--and awesomely expensive. But there is the old school choice of wood, how everybody did it back in Monty Python Camelot days: there are even some famous examples of hollowed out tree trunks or large sections of tree, burned or toasted out on the inside to affect flavor. Rene Redzeppi of Noma and Magnus Nilsen of Faviken will yield some designs.
It's also quite possible to find big ass glass bottles--they come in 5 gal, 10 and even 20--called "carboys". The advantage to which (as opposed to plastic, which retains smells and scratches during cleaning) you can use for a wide variety of stuff--you're playing with vinegar now and may find yourself cramming little fishies into it to make fish sauce in november, then can still get away with making cherry fizz in it next spring.