[TeeDubb]

I made a hard cider on a whim back in mid November. I was at the farmer's market and a local apple orchard had freshly pressed apple juice/must that had a nice combination of sweet, tannic apples that seemed like a great combo for a hard cider. I chose not to pasteurize or use camden tablets and just let the fermentation go for about 5 weeks after inoculating with US-04 ale yeast. I know that there must have been other wild yeast in the must since the final gravity went all the way down to 1.001 (if it was just the US-04, I imagine it should have stopped at around 1.010-1.014).

It tastes really nice so far, has been force carbonated and I plan to start trying one now and then as time marches on. Here is the question: I took a risk with not pasteurizing, is it safe? There was no evidence of any infection or off flavors and I obviously had about 8 oz so far with no issue. The pH finished a bit low (3. and that adds a nice touch of sour which balances some residual sweetness (even with the low gravity) and the apple flavors. I have read that a pH lower than 4.5 should kill any unwanted organisms / pathogenic bacteria. 

[dmtaylor]

S-04 can take it down to 1.001 no problem.  This is cider, not beer.  There's no complex sugars in there which the yeast cannot eat.

That said, I'm sure you have a mixed fermentation going on with multiple yeasts acting all at once.

There is nothing dangerous in wild cider.  All the nasty beasts have indeed been killed by the alcohol and the low pH, leaving you with a tasty cider that you can enjoy the same way as millions of others have done for hundreds if not thousands of years.

Cheers.

[pete b]

Whenever It’s a good apple year and I have plenty of cider I do a wild ferment with some of it. This year I had 20 gallons to work with so 5 gallons was wild. I literally put it in a fermenter with an airlock and left in my 55 degree cellar from late October until last week when I bottled it. Wild cider ages beautifully so I bottle condition it and leave it in my root cellar. I will save much of it for next fall. The rest of the cider I fermented in 5 gallon batches with commercial yeast (s04, us05, and 71b). I just used camden tablets to knock back the wild yeast. I kegged those three batches, one was a rose that I added crabapple juice to and back sweetened a little with apple juice concentrate, one I hopped in the keg with citra, and one I backsweetend with honey and blueberry juice.
I have literally made over a hundred gallons of cider without pasteurizing over the past ten years with only good results. I have had plenty of unpasteurized juice right from the press too. Unless you have an immune deficiency problem, pregnant etc. I think consuming a lot of unpasteurized cider, veggies from the garden that are merely rinsed of bigger soil particles and fermented veggies like Kim chi is great for us and more and more science is showing lack of this linked to obesity, diabetes, and more. So the question to ask might be is pasteurized cider bad for you? The answer might be yes in large quantities. It is another processed food.
BTW any yeast will ferment cider to dryness even with no wild yeast involved. It doesn’t have the unfermentable sugars malted grain does. The way to tell if the wild yeast took over is if it tastes and smells a bit funky, in a good way IMO.
I think the reason cider and mead can still seem sweet is a combination of mouthfeel, part of which is carbonation in cider, and our mind being fooled by the aroma and flavor of apple or honey.
If you find the tartness to be a bit much it’s very easy to backsweeten in a keg: add a can of apple juice concentrate or half a pound of honey and mix around. It will be too cold to ferment very quickly, just drink within a few weeks.

[kramerog]

When water was unsafe, folks drank wine (sometimes diluted with the unsafe water), beer and cider, all spontaneously fermented.  You'll be fine. 

[TeeDubb]

I appreciate the great information and feedback!  Interesting comment, pete B, about pasteurized cider being another processed food - I never thought of it that way. Now that I've found a good source for fresh pressed apple juice, I'm really excited about working a few ciders into my annual 'brewing' and letting some of it age a bit and bringing it out to share over time. What nature has provided is pretty amazing!