High gravity brewing possibilities?

[Twofox]

So we have been researching High Grav brewing with the goal of doubling production. This falls under the header of "This should work". Here's what we're thinking:

• Brew a 1.088 beer
• Use a UV sterilizer for liquor back water, and adjust the PH as needed
• Mix 50/50 in the fermenters to get a 1.044 beer
• Use our brewing software to scale up the recipe so hopping would reflect the same bu:gu ratio
• Ferment both FVs as normal

Concerns:

• Will hop utilization suffer? I've read that we might need to up hopping by 3%
• Flavor is really the key issue. As a commercial brewery, we don't want to dump a double batch.

Assuming we hit our numbers, can anyone poke holes in this process?

Cheers!

[Weehe]

I would just point out everything would be half. So if you are going for a specific mineral content you would have to add it to your diluting water. As long as the hops are mixing well in the boil I wouldn't expect a utilization change, but not 100% sure for a large system. I would also have your UV water tested to make sure it is actually sterile before use.

[dick murton]

Unfortunately it is not as simple as doubling the wort concentration and diluting. I worked for major breweries who spent ages going from 1048 up to 1060, and than more time going to 1072, and again when going up to 1080, before diluting back to sales gravity. Hop utilisation drops quite dramatically. You will need to adjust brewhouse mineral additions and times, pitching rates, wort oxygenation. You may need to change fermentation temperatures, grist ingredients, top pressures if using pressurised or tall FVs, yeast food additions. You may even need to change yeasts because the flavour changes so much, and certainly will need to watch out for low viabilities in 1088 wort compared to 1044. And your deaerated liquor additions systems needs to be exemplary - demineralised, +<10 ppb O2, sterile, etc. etc. - you are talking world class production and blending techniques. And don't forget carbonation control post dilution.

And unless you have a mash filter, you will lose extract, so your revenue costs will go up - more and possibly different malts and adjuncts due to loss of extract. Loss of hop utilisation, increase pro-rata losses - each litre of high gravity beer you lose = two litres at sales.

I strongly suggest you do it in steps so you get a feel for things as you go along.

[Twofox]

Unfortunately it is not as simple as doubling the wort concentration and diluting. I worked for major breweries who spent ages going from 1048 up to 1060, and than more time going to 1072, and again when going up to 1080, before diluting back to sales gravity. Hop utilisation drops quite dramatically. You will need to adjust brewhouse mineral additions and times, pitching rates, wort oxygenation. You may need to change fermentation temperatures, grist ingredients, top pressures if using pressurised or tall FVs, yeast food additions. You may even need to change yeasts because the flavour changes so much, and certainly will need to watch out for low viabilities in 1088 wort compared to 1044. And your deaerated liquor additions systems needs to be exemplary - demineralised, +<10 ppb O2, sterile, etc. etc. - you are talking world class production and blending techniques. And don't forget carbonation control post dilution.

And unless you have a mash filter, you will lose extract, so your revenue costs will go up - more and possibly different malts and adjuncts due to loss of extract. Loss of hop utilisation, increase pro-rata losses - each litre of high gravity beer you lose = two litres at sales.

I strongly suggest you do it in steps so you get a feel for things as you go along.

I think you're talking about post fermentation dilution. We're planning pre fermentation dilution.

[dick murton]

OK, that's simpler. However, in that case probably the most critical aspect is the cost of lost mash tun extract and to a lesser extent the hop extract. Unless you are going to boil for hours, which will bump up your energy bills considerably, you are going to have to achieve a wort gravity in excess of 1075 to get 1088 plus in copper at cast. Considering the start of runoff tends to be around 1090 (I have seen it go as high as 1104 briefly in a large mash tun (600 hl at 1048) this means you will have to throw a large amount of extract away unless you are using sugars in some form or another to compensate for the volume of wort below say 1060. And you still have the problem of high gravity residues left in the trub / whirlpool hop additions increasing the cost of these losses.

I know the tables are based on homebrew utilisations, but I think you will lose considerably more than 2% hop utilisation - the tables suggest more like 6%, down from say 23% to 17%.

You may well have to alter the mash temperature because you will probably have to use a much thicker mash and thicker mashes protect the enzymes, so you are likely to have to raise the temperature one or two degrees C.

Because you are diluting the wort pre-fermentation, if you are using wet recovered yeast, you will need to consider wort oxygenation consistency. To complicate matters, is your dilution water de-oxygenated?

As has already been said, you may need to adjust the mineral content of the mash and/or the dilution water to achieve similar mineral ion contents - afraid that is going to be a bit trial and error, and lots of analysis for accurate results.