Ice cider - fermentation won't start, extreme acidity reported

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SlowRiot

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I'm making a batch of ice cider, from apples from my own trees (not shop-bought juice). No preservatives. The constituent apples are early this year, and most of this batch is windfalls; 55% green and 45% red. These have been frozen in a chest freezer, and then shredded and pressed. The batch is ~21 litres, primary in a plastic bucket.

The freshly pressed juice tastes great, not too sour at all (back to this later).

I added campden tablets at pressing, in the recommended quantity, to mitigate browning of the juice and kill natural yeast. I waited 48 hours after the campden before proceeding.

I added pectolase and DaP nutrient in the recommended amounts.

I rehydrated and pitched the yeast, Lalvin D47, as per instructions. The yeast looked happy prior to pitching.

At this point, the Brix reading was 10.2 (1.04 SG). However, 36 hours later, there was no sign of fermentation - no airlock bubbles, which I know can be normal in a large bucket, but also no drop in SG reading or any visual sign of activity. I assumed that it could have been because my yeast had been stored out of the fridge for a long while, so I made up a new batch of yeast, pitched it, etc. Now another 48 hours has passed, and again no sign of activity of any sort, and again the SG is unchanged.

Temperature should be okay, around 18C to 20C.

I checked the pH with an inexpensive Chinese digital meter, and to my surprise, it read 1.86 - incredibly low. Although Lalvin don't give acidity specs, I understand that yeast generally are only viable from 2.0 up. It is possible that this cheap meter is reading inaccurately, so I'm waiting for more precise litmus strips to arrive, and also some calibration solutions so I can attempt to recalibrate it - so I can't confirm this reading is accurate.

I understand that freezing the apples in ice cider releases more sugars but also can make the result more acidic. Is it possible that this reading of 1.86pH is correct, in this situation? Does this sound realistic? If so should I attempt to correct the acidity first before trying to pitch again? I have potassium & calcium carbonate with which to do it, but I'm reticent to try to adjust pH if it turns out the meter I'm using is miles off the mark.

Is it worth trying to proof more yeast in this same juice, or do I just risk wasting it if the acidity is really the issue? Is there anything else I could have missed that may be the problem?

To summarise:
  • Juice from own frozen apples, no preservatives
  • Campden used but given plenty of time after
  • Nutrient added (DaP)
  • Pectolase added
  • Yeast hydrated and pitched correctly
  • SG seems reasonable to start fermentation
  • pH reading extremely low, but may be incorrect
  • No activity on airlock, no krausen, no drop in SG, 24 hours after second pitch attempt

Any advice would be very welcome!
 

doublejef

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I'm not sure about the pH because I only use Acid Titration which seems to be more accurate in cider making (an easiest to measure).

By the way there is something weird about you OG. You say it was 1.040 after pressing which is already quite low for fresh pressed juice for apple that was not frozen. Usually, a good apple juice for cider is between 1050 and 1060, if you freeze the apple to concentrate it you should get a juice around 1090 or more. My ice cider start fermentation at 1150 for example.

So you actually just have a simple apple juice. From apple that have been frozen, but simple juice anyway. Are you sure about your SG reading?
Th very low pH must come from the apple variety, what apple do you have?
Question now is, why does it not start fermenting? I have never heard about a so acid apple that the juice can't ferment so it's probably not the issue. You add nutriment, you do wait long enough between SO2 and yeast addition. Are you sure you didn't rehydrate yeast with too hot water? Is it any possibility that both yeast package was bad?
 
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SlowRiot

SlowRiot

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Thanks for the response - you were right, there's nothing wrong with the apple juice. The cheap Chinese pH meter I used was reporting nonsense, the juice was actually at 3.6pH (once tested with decent quality strips). So, nothing wrong with the acidity.

I tried again with properly rehydrated Lalvin D47 from another supplier, and now have good fermentation progressing with a lot of bubbling from the airlock.

It's possible the first two packets of yeast I tried were bad. The only other thing I can think of that I did differently, was that I took longer to carefully lower the temperature to 22C (temperature of the wort) from the rehydration temperature of 35C. It's possible I didn't do this slowly enough with my first two attempts.

So, in summary: acid had nothing to do with it, false alarm!


Just for completeness, your other questions - I have no idea what varieties of apples these are, they're a couple of trees left over from an ancient orchard, in the south east of England - one produces tart green apples, the other deep red with a blush of pink colour extending into the flesh beneath the skin. Regarding the SG - I didn't measure SG directly, but measured Brix (at 10.2), using an optical refractometer, and converted to get the SG.
 

madscientist451

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I'm making a batch of ice cider, from apples from my own trees (not shop-bought juice). No preservatives. The constituent apples are early this year, and most of this batch is windfalls; 55% green and 45% red. These have been frozen in a chest freezer, and then shredded and pressed. The batch is ~21 litres, primary in a plastic bucket.


I understand that freezing the apples in ice cider releases more sugars but also can make the result more acidic.

Ice cider is supposed to be higher ABV than regular cider. Freezing of the apples does not release more sugar. However when you freeze and PARTIALLY thaw the apples the water portion of the juice remains frozen and then the juice comes out. So what you are trying to accomplish is to concentrate the available sugar. The apples are placed in the press whole. Shredding them up will cause them to thaw out and defeat the purpose of freezing the apples.
Another method is to make the juice and then put the whole bucket in the freezer. The water portion of the juice will separate and you can remove the ice. I've done it both ways and prefer the bucket in the freezer method.
Your gravity of 1.040 is somewhat low by cider standards. Where the apples completely ripe? Storing the apples after harvest in a cool place, "sweating them" will also result in a higher gravity, and help develop more flavor. If you start with fully ripened fruit and then sweat the apples, part of your work to get higher gravity juice has been done.
You can still freeze the apples or juice after you sweat the apples.
I prefer late season apples for making cider, but you have to use what you can get, I suppose.
Here's a you tube video by Claude Jolic0eur about ice cider, there are many others explaining the different methods.
 
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SlowRiot

SlowRiot

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Thanks - interesting information. I understand the idea that crushing them frozen produces a kind of freeze-distillation effect where some of the pure water (ice) gets left behind, so you concentrate the remainder - and I did shred and crush mine from frozen, which resulted in some water ice remaining in the pulp, although probably not as much as if I had kept the apples whole when pressing. But I thought that freezing also physically breaks up the cells in the apples, and makes more of the content available to the solution, including sugars - is that not the case? Certainly the apples which have been frozen seem to give off a noticeably larger volume of juice per weight, than crushing them from fresh - honestly, I'm just glad to use the technique to increase yield at this point, rather than ABV. Perhaps I shouldn't be calling this ice cider, though?

You're right that later apples would be preferable, and some of mine are not fully ripe - I'm making this first batch of the year mostly with windfalls, and a few apples on the tree that are already ripe at this early stage - we're having a bit of a strange summer here this year, a lot of things are coming early. I expect I'll have some more ripe fruit left for later in the season, but I didn't want the windfalls to go to waste at this point! So I do expect the SG to be lower than usual in this early batch.

With the Brix I measured, I expect the result to be around 5% ABV, which is on target for what I was going for anyway, without watering down the result. I'll probably get a higher SG and % for my second batch - will update this thread with my results.
 

madscientist451

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A dirty little secret (ok its not a secret at all) of the apple industry is that most apples are picked before they are ripe, because they don't all ripen at the same time. Also ripe apples get bruised/damaged wile processing. So being able to get fully ripe fruit is a real plus and I've noticed a big difference when using tree ripened fruit vs commercial unripe fruit in cider.
The early windfalls are the first indication that its time to start picking, but its not an indication that all the apples are fully ripened.
 

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