Yeast dropped after adding apple juice.

I have a 5 gal batch of mead that started about 1.100. It’s been fermenting about 6 months. My fermentations typically go about 9 - 12 months (I don't boil my honey). I used Lavlin D47 yeast with no yeast additives. I had taken about 1/2 gal. out in samples along the way and decided to top off with some apple juice to make a cyser. I figured the SG was probably around 1.010-1.015 (did not measure it) before I added the 1/2 gal of apple juice. And that the fermentation would continue a couple of more months. The juice was clear, pasteurized, and made from concentrate but contained no preservatives or stabilizers.

A day after adding the apple juice the mead dropped clear. I just measured the SG as 1.010. The mead is perfectly clear with slight apple aroma. It tastes very good; not as sweet as I was worried about. So all in all I have no worries.

But I was wondering if anyone had any ideas why the yeast gave up. Was the exhausted yeast not able to deal with trying to convert the additional sugars? Did the apple juice alter the pH so much as to shock the yeast? Or do you think the yeast was pretty much done at that point, and the small amount of protein in the apple juice worked as a fining?

Any thoughts or similar experiences are welcome.

Thanks.

gravities?

... I mean, if it was pretty well done before you added the juice, you could tell with a hydrometer reading. If it doesn't taste sweet, it's probably done, though, and most any sort of brew will usually fall clear when most of the sugar has been eaten up.

I'd keep watching it for a good while. Apple juice has a way of pushing yeast along, and in your case the yeast has not reached its alcohol tolerance. It is quite possible that one month from now, the gravity will be a lower.

Whenever you add juice (or other liquids) to a fermentation the results can be unpredictable. Changes in the pH can speed or slow sedimentation, and the phenolic elements in the juice can bind with proteins and yeast particles to drop them out. That doesn't mean they won't keeping function though, so I would be very patient before bottling.

Whenever you add juice (or other liquids) to a fermentation the results can be unpredictable. Changes in the pH can speed or slow sedimentation, and the phenolic elements in the juice can bind with proteins and yeast particles to drop them out. That doesn't mean they won't keeping function though, so I would be very patient before bottling.

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That's pretty much what I was thinking. I was expecting to bottle something closer to 1.000 and since I perfer it a little less sweet anyway its just as well. Thanks for the suggestion.