My own thought is it helps enhance flavor and texture...if I even remember to do it.

Found the following info from Cook's Illustrated...FWIW.

Some say that scattering small bits of butter over a fruit filling keeps the juices from bubbling over in the same way that adding a bit of fat to simmering jam keeps it from foaming up in the preserving pan. The theory is that the fat disrupts the formation of bubbles on the surface of the viscous fruit mixture. Others claim that the butter simply enriches the flavor and texture of the pie filling.

THE EXPERIMENT

To see which of these theories might be true, we baked six particularly juicy double-crust fruit pies—two each of blueberry, strawberry-rhubarb, and cherry—and dotted the filling of one of each pair with 2 tablespoons of butter.

THE RESULTS

The butter neither encouraged nor hindered boilovers: Both the plain and the butter-dotted strawberry-rhubarb pies overflowed, but none of the blueberry and cherry pies did. As far as flavor and texture, tasters could not consistently identify which pies had added fat.

THE BOTTOM LINE

If your favorite family recipe calls for dotting the filling with butter, you can certainly continue to do so out of deference to tradition, but it probably won’t have much of an effect.

Oh - I'm experiencing the same thing in the kitchen and the garden! I have a retired engineer on my hands. I try to take the opportunity to teach him, but like you, I sometimes walk away - especially in the kitchen (since those results are temporal). The garden is another thing and I stand my ground, so to speak lol.

Don't know why - my mother did it, her mother did it and I do it!

It adds a rich creaminess in certain pies, like apple, but i put it under the crust before baking.

Tell him "Duh! Butter makes everything taste better" = J

Butter tastes good with apples, and it combines with the sugar to make a sort of caramel. I cheat and melt the butter and drizzle it on - it's going to melt in the oven anyway. I do the same when I am baking fish.

I learned it was to help bind the thickening agent (flour or cornstarch) into more of a real sauce than the glue that's created by mixing a non-fatty liquid (water or fruit juice) and flour or cornstarch.

What olychick said. It's not necessary when using cornstarch or tapioca as a thickener, but it really enhances the texture of flour-thickened pies.

Everything is better with butter...my father would take a huge piece of grilled porterhouse off the grill and put a stick of butter on top to melt over it. I cooked myself a steak the other night and put a big pat of butter on it....forgot how good that could be!

Re retired husbands: someone once said, "I married him for better and for worse, but not for lunch." :)

caflowerluver, your DH has a point. According to Cook's Illustrated there's no justification:

"Some say that scattering small bits of butter over a fruit filling keeps the juices from bubbling over in the same way that adding a bit of fat to simmering jam keeps it from foaming up in the preserving pan. The theory is that the fat disrupts the formation of bubbles on the surface of the viscous fruit mixture. Others claim that the butter simply enriches the flavor and texture of the pie filling.

THE EXPERIMENT

To see which of these theories might be true, we baked six particularly juicy double-crust fruit pies—two each of blueberry, strawberry-rhubarb, and cherry—and dotted the filling of one of each pair with 2 tablespoons of butter.

THE RESULTS

The butter neither encouraged nor hindered boilovers: Both the plain and the butter-dotted strawberry-rhubarb pies overflowed, but none of the blueberry and cherry pies did. As far as flavor and texture, tasters could not consistently identify which pies had added fat.

THE BOTTOM LINE

If your favorite family recipe calls for dotting the filling with butter, you can certainly continue to do so out of deference to tradition, but it probably won’t have much of an effect."

https://www.cooksillustrated.com/features/8783-should-you-top-your-fruit-pie-fillings-with

When I started baking years and years ago, I did it once or twice and reached the conclusion it was superfluous. I wasn't a man or retired at the time, and I still am neither, but now that I ran a search after getting curious reading this thread, I know I was right.

Wintercat, that is an interesting experiment, but I notice Cook's Illustrated is only testing the theory of whether butter prevents boilovers, which is not why I add butter to some pies. The article also doesn't mention what they use for thickening - flour, cornstarch, tapioca or something else. The types of pie they used for the experiment (blueberry, cherry and strawberry rhubarb) are pies that I would use either cornstarch or tapioca to thicken, not flour, and I think most traditional recipes are the same (cornstarch and tapioca produce a glossier, more translucent filling than flour, which looks better with berries, and a cleaner flavor that goes well with the more delicate, juicy fruits). By that same token, I would not dot these pies with butter before baking, because neither cornstarch nor tapioca turn to a roux when combined with butter the way that flour does.

However, when using flour as a thickener, butter absolutely creates a nicer "pie goo" texture than flour alone, the same way that a roux or beurre manie is nicer for thickening a sauce than just a flour/water slurry. The pie will still thicken without the butter, but the consistency and richness of the pie goo will not be as velvety. That velvety-ness is not what I want in a berry pie, but it is ESSENTIAL for great apple pie IMO. I like peach pie thickened with flour (and butter) as well.

Absolutely...I think cooks Illustrated gets too wound up in scientific processing and overlooks that very subjective thing of taste and mouth feel....butter it is!

I am not sure if I tasted the butter or not, but it was good so gave him a pat on the back. I prefer minute tapioca to thicken, so I guess didn't really need the butter.

I use tapioca to thicken. too. It's especially good for Mom's Apple Pie. That has neither butter nor sugar in the filling. Just spices, tapioca and the juices from the apples. For a little to no sugar added blueberry or blackberry pie, even with tapioca for the thickening, I think a little butter does enhance the texture of the goo. Same as if one were making a berry syrup topping. A little butter makes it silky and gives it body, rather than being just runny berry sugar water. ;) I don't like it with strawberries, however, and prefer my apple lean. Good with peach, though. A great peach syrup is just very ripe peaches poached in butter and sugar under the flesh is completely melted. So the butter in the pie is a good step in that direction. :)

I always use pate brisee w/ all butter for dessert pies, so no need to gild the lily. I do dot my fruit crisps w/ butter.

All of my old recipes say to add pats of butter, and sometimes I remember and sometimes I don't. I normally use flour to thicken because that's what I like. The pie is good both ways and truthfully, I can't tell the difference between the pies with butter and those without it.

I think we had this conversation here several years ago, but I can't find an old thread, so maybe no....

Annie

Don't know why - my mother did it, her mother did it and I do it!

This reminds me of a family story. Around the holidays, the family would get a large ham. It was always cooked the same way, but the ends were cut off and repurposed for other dishes, or held a couple days for ham and beans or the like.

anyway, one of the kids was asking why the holiday ham always had the ends cut off, so he was told to 'go ask mom.' When mom was asked, she said it was the way she learned from her mom, but wasn't quite sure so, 'go ask grandma.'

so the curious youngster approached grandma and asked why the ends were cut off the ham before it went in the oven. The answer took him by surprise. "Because it fits in the pan better," she said.

true story

I use an all butte pate brisee too....and dot the pie with butter....as for not adding sugar to apples....depends on the apples. I grew up with 2 apple tree in the yard, and as soon as they were a little bigger than a golf ball, we started making pies....as the season progressed, the amount of sugar got less.

Linda, the tasters in Cook's experiment couldn't distinguish butter-dotted from non butter-dotted pies.

"Others claim that the butter simply enriches the flavor and texture of the pie filling... As far as flavor and texture, tasters could not consistently identify which pies had added fat."

Taste is of course subjective. I make my crusts with butter and for me this creates so much buttery flavour that dotting the filling with butter doesn't make a difference.

I tried to imaging how dotting with butter developed as a tradition and it occurred to me that long ago people made their own butter, didn't have a fridge to stick the butter in, didn't want to waste good butter, so used up what remained by dotting the pie with it.

it occurred to me that long ago people made their own butter, didn't have a fridge to stick the butter in,

Yes, but you can keep butter without a fridge, you know. They did, using a number of different methods including putting butter down the well in hot weather (old wells often have niches in their sides for butter if you stick your hand down in and feel along the sides), butter bell crocks, and just plain leaving it out. (You'll also see a lot of unsurprising references in old book to butter getting "strong," BTW.)

writersblock ... Yes, but you can keep butter without a fridge, you know.

I was 9 or 10 when we first got electricity. I vaguely remember strong butter. I think my folks called it rancid. On the farm surpluses went to feed pigs, chickens and hound dogs. I don't recall it being utilized or a problem or concern.

I think strong came before rancid. Butter could also be strong if the cows had been eating, say, turnips during the winter and the butter was freshly-made.

But yes, they used everything. My mother was a product of the Depression era and she had a firm belief in the immortality of food as a result.

My daughter uses a butter bell. I just use whipped butter which can stay out on the counter all the time if there is AC in the house.

I never take Cook's Illustrated too seriously. Their results often don't match my own observation, even on failrly objective things.

What the butter does when I put it in pies is just add a little body to the juice. It's not going to make a much difference in taste. Someone who was looking for it would find it. I do. But to identify it as more than just "good pie", you'd want to be scraping the juice off the plate with the side of your fork. Or dismembering the crust and dunking it, like a little kid. I don't know what it's like when there's a flour thickener, though. That might be a more pronounced difference.

The waste-not theory makes some sense, and I wouldn't be surprised if there were some who did just that, but I think for a widespread practice, there would have been a more specific reason. The boil over theory makes a lot of sense even if it doesn't work when tested. If it works with jam, and everyone thought it would work with pies, and if, perhaps, adding the butter prevented the bakers from overstuffing the last bit of filling into the pie so they could put the butter where they wanted, so they actually didn't boil over... That kind of folklore lives. Like the canard about putting a cut onion by a sick person's bed. People still believe that even though it's hoooey. A good story trumps practicality. Anyway, a few dabs of butter could be used on the scraps of crust cookies. :)

I got several months of CI free with something...maybe an appliance....
Anyhow I have never read it before that.....and I soon realized they were trying to act like chemists with something as subjective as food, and trying to be precise while not considering what the chickens that laid the eggs had eaten and just how that flour had been stored before youw eighed it.
So I will dab my apple pie with butter even fi they say they can't tell the difference.

I can’t remember ever doing that!