Making up short brew length

[Tensbrewer]

I normally brew strongish IPA using a cool box mash tun. My output from the tun post sparging is always a little short - say if I am aiming for 30 litre brew length, I generally end up with something like 25 litres from the mash tun before stopping the sparge because the gravity of the wort will have dropped to 1.010. Its not normally an issue, I adjust the hopping in the boiler to compensate for the reduced volume and things work out fine.

I am however contemplating a traditional English bitter with an final ABV of something like 3.9-4.0% and with the thinner wort, my fear is that I will end up with a substantially lower yield out of the mash tun before I reach 1.010. Should I just accpet this, or is it feasible to sparge on with the wort below OG 1.010 or make up the short volume with hot liquor?

Help!?

[JonB]

You will get about 10 different answers to this question if you go hunting online, I will outline my experiences below:

Personally I just sparge until I get the correct volume irrespective of runnings gravity and have not experienced any noticeable side-effects (even with mash efficiency percentages in the 90s).

My understanding is that tanin extraction (allegedly the bad consequences of over-sparging) only really occurs if the pH in the grain bed gets to about 8-9ish or upwards (more alkali) during this process; not 100% sure on the numbers though. Generally speaking my mash pH is around the 5.something mark, and the water out of my tap is ~7-8. Assuming I've got this right then if you have particularly hard/alkali water then there is potential this might be an issue, but I believe not if you have soft water.

The other alternative is to carry on as you normally do, but use your normal water source to "top-up" your sparged wort to the required pre-boil volume and add some light malt extract if the pre-boil gravity is a little light. There is no reason why you can't do this with any consequence other than a higher final volume. You could of course add pre-boiled & cooled water to the fermenter to correct shortages in the final volume (don't adjust your hop quantities if doing this), but it would be better to correct pre-boil as you'll get (fractionally) better utilisation of your hops.

Hope this helps.

[Tensbrewer]

Thank you very much for that, yes, my instinct was to just keep on sparging as i felt it better to make up to full volume with sparged wort rather than just liquor, the former would impart some flavour and colour even if this was minimal. My fear if I stopped at 1.010 is that rather than making a lighter beer, I'd just end up with a smaller volume of beer of the same sort of strength that i normally make. Normally making beer with a pre boil OG of say 1.058 and getting say 25 litres (from a hoped for 30l) from 9kg of grain before I reach wort of 1.010, if I used say 6kg of grain with the intention of getting c 25l of a lighter wort, if I stop at 1.010 and don't add extra water or something to the wort I'd just end up with a smaller quantity, (say 18l) of wort with the same 1.058 OG.

Looks like I'll try keeping the sparge going. Our water is moderate hardness 111mg/l CaCO3 so hopefully that will be ok, I don't normally undertake water treatment other than Campden to counteract chloramination but I guess a little citric acid might reduce the risk of tanins?

[Eric]

To answer your initial question, yes, you can. My last runnings are frequently less than 1005, but little value is obtained at such low levels.

As said, the reason for stopping at a particular gravity is to limit pH increasing above the level when unwanted products are released. My target is to be < pH 5.6 for both mash and runnings, achieved by reducing alkalinity, more for sparge than mash liquor. Neither hardness nor pH of supply water provide any indication of what mash pH might be.

For gravity to drop to 1010 on a "strongish" brew before reaching target final volume, suggests either all sugars had been quickly extracted, or more probably your sparging efficiency could be better. That would lower the rate that gravity falls when sparging.

It is usual for efficiency for stronger beers to be lower than weaker ones.

Sparge a bit slower and try to avoid sparge liquor making channels through the grain.

[JonB]

Eric's tip on slowing the sparge down is something I don't think is particularly well documented in the literature (at least not in my experience), but is probably the easiest way to solve efficiency problems.

Just to put some numbers to it, it takes my 3-vessel system about 1-1.5hrs to sparge 25/27l of wort, it really is coming out with a trickle.

This pushes my typical mash efficiency to 80/85% depending on the recipe even with 1.060+ gravity beers.

(I haven't measured mine for a long time, but I'd be surprised if the last couple of sparged litres were above 1.005 gravity...)

[charliemartin]

Alternatively you could batch sparge. I do two batch sparges splitting the sparge water equally and recirculating for about 10 to 15 minutes each time followed by a slowish runoff.
With this method your runnings will never go as low as 1.005.
I regularly achieve efficiency of over 80% with this method.

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