Batch Sparge

[Touchstone]

Is it possible to over sparge with batch sparging , I only sparge to my pre boil volume , but I'm wondering if stirring too much or too vigorously might cause astringency?

[MTW]

I batch sparged my first few AG brews with good success, in a coolbox tun.

If anything, in theory, you're less likely to over extract and end up pulling tannins by batch sparging. A bad batch sparge is probably better than a bad fly sparge in some ways, at least as far as off tastes is concerned. I got decent efficiency batch sparging too.

As for stirring, you want to get an even temperature, so definitely do. I have read theories about some sort of unwanted oxidation causing off flavours at that stage, and 'LODO' is a big thing in the USA at the moment (check out their forums) but I wouldn't be too concerned. Temperature, extraction and and mash pH remain the main things.

[Eric]

Yes, I suppose it is possible to induce astringency by what could be called oversparging when batch sparging although it is more likely when fly sparging, but I wouldn't expect it to be caused simply by stirring.

Introducing astringent components into wort during sparging is normally the result of too high a mash pH or when there no sugars are left and only undesirables can be extracted. It is unlikely this latter stage will be achieved when batch sparging, but regardless of whatever method of sparging, if mash pH is very high, astringency will be present in the finished beer.

It might be assumed that two buffering forces exist at the end of the mash, sugars that have been created and minerals in the liquor. As the sugars are rinsed from the grains their buffering powers will deminish while those of the liquor may be replenished depending upon the properties of the sparge liquor used. Alkalinity in the liquor will tend to raise pH and as the sugars thin and their buffering capacity declines, mash pH will rise. This is more of a concern when fly sparging as the object is to extract as much of the sugars as practical, but in each batch sparge the pH will remain more or less constant with an even distribution of the sugars and shouldn't create a situation of an entire batch with very dilute sugar content.

Obviously it is not in your beer's interest to permit a turbid wort entry into your kettle, recycling until as little haze as possible is achieved will help reduce problems caused by such wort and not be the cause of astringency.

Do you know the properties of your water and do you treat it?

[Rad]

What Eric said, but also too high sparge temperature can wash more tannins from the husks.

[Touchstone]

Thanks for all replies , very helpful.
I've had a ongoing problem with astringency for some time , on my last brew I checked the mash Ph with a newly acquired meter and it was 6.4 , with the current brew still fermenting I included 6 grms of AMS in the HLT which brought Ph to 5.2. My question is would a Ph of 6.4 have caused my astringency problem , how critical can it be?

[Touchstone]

My water here in south Cheshire is not too hard, and I include campden tab in the HLT

[MTW]

6.4 sounds very high to me, and is well outside the sort of 5.2-5.6 area that I'd be happy with for most brews. Maybe that was indeed your problem. Was that in very pale beers, with untreated liquor?

It seems unlikely to me that 6g AMS in the HLT alone would make make 1.2pH difference in a 20L+ batch size, so maybe your batch size is small (?), the grain bill was different, the alkalinity of the water supply has changed, or you pH meter is out.

The campden tablet will only make a minuscule difference to the alkalinity and therefore pH.

I guess you're moving on to looking at liquor treatment here, rather than sparge method, so check out the water treatment tabs on here as a primer.

[Eric]

pH 6.4 will be the cause of significant astringency. You will need to get to grips with your water.

Get it tested by WallyBrew keeping a sample of what you send him.
Buy a cheap TDS meter which will instantly reveal variations in your water's mineral content. Using it on the sample sent for analysis will show how close your brew water is to that analysed.
Buy a Salifert Kit. Use it to measure alkalinity before and after treatment with AMS or other acids. Reduce alkalinity for pales and sparge liquor to around 25mg/l as calcium carbonate. Mash liquor for darker beers and those with much crystal should be higher.
With the findings of the analysis you will be able to adjust the level of calcium present in the mash, sparge and boil to make the style of beer you desire.

[Touchstone]

Thanks for replies , much appreciated, I have something to work on now

[BrannigansLove]

I acidify my sparge water to about 5.6 (whatever the recommendation in Bru'n Water) to avoid this.

[Eric]

I acidify my sparge water to about 5.6 (whatever the recommendation in Bru'n Water) to avoid this.

You might want to measure the alkalinity of your water at pH 5.6, mine can have alkalinity in excess of 100ppm as calcium carbonate at pH 5.6 depending upon the day. Not a good measure to use.

pH 4.4 is the accepted measurement for alkalinity to have been neutralised by acid.

[BrannigansLove]

I acidify my sparge water to about 5.6 (whatever the recommendation in Bru'n Water) to avoid this.

You might want to measure the alkalinity of your water at pH 5.6, mine can have alkalinity in excess of 100ppm as calcium carbonate at pH 5.6 depending upon the day. Not a good measure to use.

pH 4.4 is the accepted measurement for alkalinity to have been neutralised by acid.

I've recently started measuring alkalinity of my base water before any additions, and it's generally been slightly over 100 (103 for my last brew).

[Eric]

In that case it is highly improbable your alkalinity will be as high as I suggested. Nonetheless, it might be worth checking alkalinity at that pH and that final runnings don't rise much above pH 5.6.