Can I use canned peaches in peach blueberry pie? My sense is that I would eliminate some of the sugar (1 cup) called for, and perhaps dry the peaches a little. Suggestions please. Thanks !!
Frozen fruit is always the better option than canned. As Chester pointed out, there's the liquid issue. Liquid means soggy bottom. Despite the perception that frozen fruit produces more liquid than fresh, that is actually not the case. Fresh fruit and vegetables are flash frozen. There's no additional water added in the process. So the only liquid in the fruit is the natural juice.
Aside from the liquid issues with canned fruit, there is the issue of texture. The canning process requires heating the canned peaches in boiling water for 30 minutes to ensure all bacteria is killed. The cooking gives the peaches an unpleasant rubbery texture.
I use frozen fruit frequently for pies especially in the fall and winter after peak season for fruit is long gone. I always have frozen wild blueberries in the freezer for pie.
I find frozen fruit is generally very sweet because it's picked and frozen at its peak. Frozen fruit will cook down slightly more than fresh fruit. So I always slightly over-fill the pie plate.
Small fruit like blueberries can be baked frozen. But peaches do better thawed to about 45° - 50°. Essentially the temperature they would be had they been stored in the refrigerator.
I recently tried ratios of sugar and tapioca starch for thickening that worked spot on. The ratios are from pastry chef Stella Parks.
For fruits like peaches and apples:
25% sugar to the weight of the fruit
4% tapioca starch to the weight of the fruit
So if you have 1 1/2 lbs of fruit:
24 x .25 = 6 ounces of sugar
24 x .04 = 0.96 round up to 1 ounce tapioca starch
For really juicy fruit like blueberries:
25% sugar to the weight of the fruit
5.5% tapioca starch to the weight of the fruit
Just a couple of weeks ago I baked several blueberry pies to test ratios. I used frozen blueberries. The ratios are accurate. The filling was perfectly set.
Reducing the tapioca starch by a mere 1% produced a looser pie filling. Not really runny, but it did move slightly after the sliced pie sat for 15 minutes. I actually preferred the slightly softer filling. So if you want a slightly softer set for blueberries, I'd say 4.5% tapioca is about as low as you can go without juice making a soggy crust and a mess when you cut the pie.
In the past I found it was hit and miss with thickening the filling. But I have been taught to use instant tapioca rather than tapioca starch. The tapioca starch really is the better thickener.
There's also a thickening product called Instant Clearjel but it's not available in stores, you have to mail order it which can be very inconvenient. But I find the tapioca starch works very well. Unlike flour and cornstarch, it does not produce a cloudy or overly gooey filling.
PS everyone can tell when it's canned fruit because of the color and texture. But frozen fruit is nearly undetectable from fresh