What is fermenting there?

[Lapja]

I have been brewing beer for many years now and have had some experiences with ciders but mostly from kits. I have plaato digital airlock that works well with beers ( it is a device that measures bubbles to provide feedback of SG and ABV through an app).

Yesterday I thought I'd try what I thought a simple recipe:
-14l apple juice
-4l pineapple juice
- 400g of honey
-kveik voss yeast

Now I did the stupid mistake not to measure the OG thinking that I'd be somewhere around 1.055 - 1060 (as usual... in beer).

Fermentation is twice more vivid than in beer and Plaato gives me after 24h an estimated SG of 0.998 and an ABV of 9%....and is still fermenting like crazy with very little slowing down..... that's just not seem possible!

Again the device is very precise with beer wort and I have even used an Ispindle to verify it. Is there something that I am missing here?

I do realize that cider may finish lower than 1.000 but this looks like is going to finish at some strangely low numbers. I wasn't expecting to brew wine...

 

[CKuhns]

Most Apple Juice i have used is typically 1.050 to 1.060 Not sure about pineapple but could be a bit higher. I don't think there is a direct correlation for your Plaato airlock as the sugars in apple juice are significantly more accessible to the yeast than the starches and sugars in your beer mash.

An OG very rough estimate... (likely close) Assume 1.060 SG from the juice(s) + 400Gr Honey or about 0.9 lb of honey in 18L or 4.75 US G contributes about 0.008 SG.
So 1.060+0.008= 1.068 and 1.068 * 131.25 = a potential alcohol of 8.9% if hitting 1.000 FG. Of course a little higher if the pineapple has more sugar and or if you actually end up somewhere near 0.990.

I would check it with a hydrometer or Brix instrument to actually see where you are at and if there is a loose correlation to your Plaato.

 

[Lapja]

Yes indeed, it ended abruptly at 0.990 with 9,3% abv. I have never seen yeast going from full fermentation to a full stop in 30min. It was like.. this is it! Checked with hydrometer and Plaato was mostly correct with a slight offset.

Now the result doesn't taste bad, but is still too strong for me and my wife that we're aiming to a light summer cider. Perhaps dilute it with water? We'll see, but fun experience and a few lessons to remember.