Adding Fruit to Kolsch style at Lager

[JStockton]

My latest experiment is a Kolsch style. I typically make a few 1 gallon trials in case I want to try something out. I found what looks like a nice Peach Kolsch style recipe to try the first time. Maybe mistake #1 of a few?
What struck me as weird is that frozen peaches are added after fermentation, during lager stage only. I can not find any research on the Internet where fruit is added, and not accounted for during one or more of ferment stages? If that statement makes sense. If I understand it, I would want it in a second ferment to preserve much flavor and essence but need to ferment out those extra sugars I just added. (was very worried about bottle stage and having extra sugars there in quantity I can't allow for and going Boom)
I should have asked ahead of time because I won't know for another 6 weeks how these couple of gallons end up. I went with gut and kept the Kolsch at 60 after first 7 days and put into new 1gal with frozen peach mash in one, frozen raspberry mash in one, no addition in one so I get an idea of what the brew itself taste like for a second ferment window of 7 days. (I normally only make a single 3gal brew if I'm doing a 'large' batch as that's plenty for me)
The one gal batches aren't efficient use of resources and cost me more but over the last couple of years as a new brewer I think I've been able to maybe learn more by trying my hand at a dozen types in mini batches? First time with new freezer and temp control to be better at my new hobby I have enjoyed very much starting to learn.
I apologize in advance if I should not put a like to another site in a post but didn't know another way to share what I started with. Sorry. https://www.craftbeering.com/kolsch-beer/

 

[HighVoltageMan!]

I think your instinct to add fruit in a secondary is correct. Fruit will bring in added sugars, those need to be ferment out so the beer isn’t sweet. By secondary, I mean to add the fruit after a good portion of the fermentation is finished. You don’t have to transfer to another vessel, if you have room in the primary, then add it to the primary vessel. It can be lagered in the primary too.

I am a big fan of Kolsch’s and they are very delightful when correctly executed. The beer should be fermented at least at 60F or lower. I have been using Wyeast 1007 and love that yeast for Kolsch. It produces a fair amount of acid, which Kölsch styles are known for, and a hint of fruitiness. I ferment them at 55F, but 60 would work fine too. The other yeast is WLP029, which is an exceptional acid producer, which produces a beer with an acidic snap to it. With the peaches it may work well, but with raspberries it may be a bit tart. But that may be what your after. The other 2 Kolsch yeast I’ve used are wyeast 2565 and K 97. I’m not too fond off these because the fruitiness is a little too high, but since your adding fruit, it might work out.

I’m a straight up Kolsch guy, so too me the simplicity of the beer is what makes it work. It’s a simple beer but it’s proper execution is not. Just like a any light lager, it’s a “naked” beer, any flaws in the process show up in the beer. It’s usually a gateway beer to full blown lagers. Watch out, those lagers can become obsessions.

 

[J A]

Personally, I'd save the Kolsch for a clean, malty beer and use the fruit in a Blonde ale with US-05 (slightly peachy flavor on its own).
But if I were adding fruit to a "lagered" beer, I'd want to get it in the fermentation stage, probably during diacetyl- rest phase, depending on yeast strain. Bottom line, all fermentation completely finished, including fruit, then drop to lagering temps of near freezing for a few weeks or bottle, carb and lager in the bottle.

 

[JStockton]

Thank you both very much for the advice. My all-grains have always been pretty easy and this is the gateway to more advanced.