Originally Posted by the_Barberian
Thank you for the swift reply Jacob,
I'm using apple juice (no pulp) which has a very low pH. The low pH I've compensated by adding tartaric acid(at my previous trial)
Would it be a problem adding tannins considering that I am adding acids to the juice before fermentation as well. (of course I will add yeast and nutrients as well)
P.S. Jacob, wouldn't be risky using an open top fermenter, considering the bacteria which can get in and the abundance of oxygen that can help it thrive...
"Low pH" means “high” acid. (so to speak)
I assume you mean your apple juice has high pH (that is, not so much acid) ... ? ... and so you added some tartaric.
(And by the way, if you are adding acid prior to fermentation you should have some pH test tape to measure the effect of the acid on pH.)
Too low a pH (that is, too high of acid) can cause your ferment to stall.
As far as tannins and the ferment ... tannins do not specifically cause problems with the yeast being successful.
To help insure the success of your yeast, you don’t want your pH much lower than about 3.4 or so. Adding too much acid can cause it to be too low; and in fact as the ferment progresses, the cider can become even lower pH on its own ... risking your yeast stalling.
A good starting number is somewhere between 3.5 and 3.7 ... you want the number high enough for your yeast to be happy ... but low enough that the pH also helps prevent infection. Like I say ... you need to be measuring the number with test tape if you are going to be adjusting the pH. Much more about pH and measuring it can be found on this forum if you read-around.
As far as the open top fermenter:
You would stretch a thin piece of clean cloth (such as a t-shirt) over the top of the bucket to keep things from falling in it ... to keep fruit flies and other bugs out etc.
Bacteria is not specifically more likely to get in with an open top fermenter ... keeping bacteria from taking hold has mostly to do with following all the other proper sanitation procedures with how you clean all your equipment. Some other practices too such as the use of sulfites, choice of yeast, pH, temperatures etc ... much of that information can be found on this website and generally by doing the “homework” to learn it from reading at length.
But again ... avoiding infections has much do with how well you keep your equipment clean and sanitized ... and by not sticking unsanitized things into the cider that will introduce bacteria such as unsanitized spoons, your unwashed hands, contact with unsanitized tubing etc etc.
As far as oxygen getting in with an open top fermenter .... as the cider is fermenting it gives off carbon dioxide which helps prevent the oxygen from the air from getting into the cider and causing problems (generally at the surface). Furthermore, all yeast produce their own sulfites, some more than others; and that also helps protect your cider. Yeast are generally happiest with the exposure to oxygen from the open top fermenter; and the happier your yeast are the more likely they will be able to overcome other organisms with a successful fermentation.
Fermenting cider is notorious for getting an unpleasant sulfur odor if you do not provide very good conditions for the yeast. One of those conditions is having enough oxygen for the yeast to use. Good oxygen is your apple juice having some free oxygen in it to begin with .... this is sometimes done by shaking or stirring the hell out of your juice before you add the yeast ... adequate oxygen is also helped by having your primary fermenter open.
No shortcuts for all the research. Read, read and read some more.