What is the purpose of the Vorlauf?

Why vorlauf? What is the advantage? Won't any debris from the mash just settle out in the kettle or even more so in the fermenter? I'm batch sparging if it makes a difference.

from the wiki:

https://www.homebrewtalk.com/wiki/index.php/Vorlauf

You want to minimize grain husks in your boil because they give off sharp, bitter flavors at high temperatures. Best to reduce that as much as possible. Vorlauf also helps prevent stuck sparges. Batch sparging just means you'll have to vorlauf twice.

I think if grain gets into the wort and is boiled for the 60-90 min you wouls extract tanins and get off flavors in your end product. The vorlauf greats a filter out of the grain bed and should be done with each sparge as well.
This is an assumption on my part...

In a decoction, husks are thoroughly boiled. So I doubt that's a major concern here. I think clarity is probably the biggest reason, but you're right - just let that stuff settle out as the beer cools and ages.

Personally, I recirculate about a gallon mostly because it helps the grain bed settle a bit... then I can fit more sparge water on top.

kanzimonson said:

In a decoction, husks are thoroughly boiled. So I doubt that's a major concern here. I think clarity is probably the biggest reason, but you're right - just let that stuff settle out as the beer cools and ages.

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yep. I agree with you. Many people "claim" tannin extraction and off flavors from not vorlaufing, but there's been plenty of discussion on here about people that forgot to vorlauf and still wound up with a great beer.

kanzimonson said:

In a decoction, husks are thoroughly boiled. So I doubt that's a major concern here.

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It's actually a little different. Given that the husks have the wort sugars to buffer them in the decoction, they don't leech tanins as they would without the sugars. That's one reason why fly spargers monitor the gravity; once the amount of sugars drop, you risk leeching tanins around 170*. But with the sugars, you can certainly boil the grain without any astringency.

How do these BIAB guys get away with what they do. It's not like they can vorlauf. So is it really essential?

maida7 said:

How do these BIAB guys get away with what they do. It's not like they can vorlauf. So is it really essential?

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Fine mesh bag captures those small particles of grain.

samc said:

Fine mesh bag captures those small particles of grain.

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So why not put a mesh bag over your manifold and skip the vorlauf? I'm just asking.

Vorlaufing is a common practice in most German and other lager breweries that are producing clean crisp lager beers. Any extra grain in the kettle is said to give a burnt grainy flavor to their beers, so a lot of German brewers swear by clear wort into the kettle to give the cleanest beer in the end. While decoction mashing, steps are taken to prevent any grain from settling on the bottom that could give a burnt or grainy taste, during the boil this doesn't happen so grain particles could settle on the bottom and burn a little. American craft brewers on the other hand aren't as concerned with a little gran in the kettle, because it isn't going to make a noticeable difference in the final beers which tend to be fuller bodied and more flavorful.

On some of the beers that we make we don't bother with a vorlauf at all because we get a better run off without doing one, and on others we always recirc for about 5 minutes. It just depends on your setup and what you are brewing, but it isn't a crucial step. You don't want an excessive amount of grain to get into the kettle, but a little isn't going to be a big deal, if your runoff starts out relatively clear, you may not need to vorlauf, but the extra 5 minutes it takes to recirculate isn't that long and may result in a cleaner beer.

maida7 said:

So why not put a mesh bag over your manifold and skip the vorlauf? I'm just asking.

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Actually the BIAB method generally produces quite good results, often giving home brewers extraction efficiencies upwards of 80%. So why wouldn't you do it? If it's what you want to do, go for it!

RE: Tannin extraction from husks...

My last batch I was trying something new, but hadn't thought through all the details enough... it was a partial mash where I added 1 lb of specialty grains to the kettle with my boil water, brought it to boiling, added the DME/hops & boiled for 60 min (at some point in this process before it reached boiling I'd planned on filtering out the grains, but hadn't thought about how I planned to do that - so they stayed in throughout the boil and a bunch got into the fermenter). In the finished product I don't detect any bad effects whatsoever from having boiled the grains with the wort.

Could a few husks from not vorlaufing make that much of a difference? On the other hand, why not vorlauf? - seems like a pretty easy step to me.

EDIT: Some astringency is developing now, almost 4 weeks from bottling, due to aging most likely. Not the best taste.

Vorlauf is one of those thing that people do because they believe they are supposed to. In my steel braid mash-tun I found it to be completely un-necessary as the wort runs "clear" in about 2 seconds.

My new 10 Gal RM cooler with a false bottom may be a different story. I haven't used it yet, but If I need to vorlauf I will.

Hophazard said:

It's actually a little different. Given that the husks have the wort sugars to buffer them in the decoction, they don't leech tanins as they would without the sugars. That's one reason why fly spargers monitor the gravity; once the amount of sugars drop, you risk leeching tanins around 170*. But with the sugars, you can certainly boil the grain without any astringency.

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This is no different at all. There is a ton of sugar in the wort to buffer the grains.

This is great info. I did my first AG the other day and was concerned because it seems to run clear right away. I thought i was doing something wrong.