I crushed and pressed my own pears this year hoping to make a perry. The original specific gravity (SG) was only 1.034 so I added 5 pounds (2.3 kg) of sugar, some British ale yeast and yeast energizer. It fermented for a bit, then stopped at about 1.025 and tastes very sweet. I then added a white wine yeast, but it still did not ferment. I also made a batch with both apples and pears and added 5 pounds (2.3 kg) of sugar. Like the perry, it fermented then stopped short and is sweet. I suspect the pears have non-fermentable sugars. Is there anything I can do to encourage further fermentation, or should I learn to enjoy sweet wines? One more note, we made a batch of perry from the same pear tree two years ago and it was delicious and dry. We let those pears soften much longer than the ones we used this year. Did allowing the pears to become very soft prior to pressing change the sugars to become more fermentable?
Kevin Buck
Via email

The latter reason is particularly interesting because fermentations conducted with high levels of dry sugar (beet, cane, etc) often don't have the required nutrients or healthy fermentation factors your average yeast beastie requires. Perhaps the year you started with riper fruit, your yeast enjoyed the goodies (amino acids, pantothenate, biotin, vitamins, nitrogen, not to mention suspended solids/pulp that are often important for fermentation kinetics) that come with fermenting real fruit juice rather than a white sugar solution. Pure sugar adds degrees Brix to a fermentation (higher potential alcohol), but little else