longer boil, missing OG by many points

[Crusader-Rob]

hi all, i recently completed my first 90 min boil, with a scottish ale, as detailed in the recipe advice thread.

the predicted og at 70% was 1.063, and i ended up with 1.057 and thus missed my points by 6! now it was a 90 min boil, and with my 60 min boil i normally only miss it if any by maybe 1-2 points, why the big difference in OG for a longerboil?

And will this affect the final product? (apart from the abv of course) I was expecting an OG of 1.018 with my high 68 degree mash, and the specialties in place with english burton MJ yeast.

Anything I should be aware of?

[Druid]

Was the recipe tweaked for your gear?

Was your boil gravity also lower than expected? If it was, then you lost the points during your mash. Higher gravity mashes usually end up in lower efficiencies too.

Did you boil off as much as was predicted? Not boiling off enough will give you a less concentrated wort which will also account for the shortfall.

Other than that, if you boiled off the predicted amount of water from a boil gravity that's correct, you'll have the dubious honor of violating the laws of physics!

It probably will affect your final gravity but it'll just a different beer - a Scottish ale probably relies on a solid malt base so maybe it'll be a mild instead?

[Peter Smith]

How are you reading the OG?   My so called temp corrected refractometer....     reads about 3 lower when wort is hot ie if it reads 1.057 while wort is hot, will read about 1.060 once wort cools to 20C,  I also seem to get a few extra pips when using gladfields base malts vs MO.   I always record my pre boil OG and volume before boil now, I get slightly less boil off while double batching as you would expect.

[Richard Rice]

I've recently been having problems with my efficiency too - talked to brewshop and they adjusted the mill and that's made a difference!  Recently I've been exceeding my efficiency and have had to dilute my wort recently to get expected volume as well as expected gravity.

 

I use a hydrometer rather than a refractometer, but agree you need to adjust for temp.  I have a tool on brewmate that helps me calculate that.

[Ralph]

Hey Rob. A couple of things.

As you aim for higher OGs in the same size mash tun the efficiency of the mash can drop a bit. Did you account for this? Did you measure the gravity before the boil and was it what you were expecting?

If you ended up with more volume of wort at a lower OG I would check your evaporation rate. If your evaporation number for your gear is off then the longer you boil the more you are likely to miss the OG by. This can be effected by how hard you are boiling and humidity etc.

[Crusader-Rob]

I boiled off and ended up with 22 litres as expected. My preboil was 5 points lower than Predicted so I'm not surprised I ended up lower. Probably should've added some DME but hey live and learn.
Will my FG Be affected?
So why the drop in efficiency? Too much water mash too thin?

[Ralph]

The higher the gravity you are aiming for the less sugars are extracted from the grains. If you have just water the sugars can dissolve into the water easily. At a low gravity most of the sugars will come out of the grain. As you increase the amount of sugars dissolved in the water less sugars will be extracted from the grain.

If you are fly sparging or something then you can extract most of the sugars, but if batch sparging or BIAB as you aim for a higher gravities the efficiency will fall.

[Richard Rice]

Glad I started following this - good to know as I do BIAB and I'm looking at doing a wee heavy in the new year - about 1.085 expected OG.  Would dunk sparging the bag help?  Or something along those lines?  Or increase the mash volume and boil off longer (I did read that a 2 hour boil is generally acceptable for a wee heavy)?

[Ralph]

Or just adjust your efficiency down and add a bit more grain to get to the same OG...

Increasing mash volume and longer boil will probably have a better mash efficiency, but it is worth weighing up what the extra time is worth and for that matter how much the extra gas or electricity costs... often an extra bit of base malt at $4 a kg is a very small price to pay.

Longer boils may have more caramelisation of the wort? Boiling for longer may give more of a classic wee heavy flavour? I dont know and have not made one.

[Grant R Baker]

I think the others have covered it.

If volume targets were okay then it is likely the grain crush or mash just wasn't as efficient as normal (which happens). Very unlikely that the 90min boil is at fault there.

Lower OG and FG means your beer will be thinner, less sweet and potentially not balanced against yer hop bill..but none of that means it will be a right off, it could be your best brew yet.

[Crusader-Rob]

Haha, Best Brew yet, that'd be great. Who knows, time will tell.

It was a definite Mash efficiency issue, I'm BIAB, and don't sparge, so I assume the additional 3 litres to get my volumes correct was part of the issue. Lower OG is a pain, but if my FG remains where I wanted it to be, then I should in theory end up with a similar body beer??

It was a scottish ale, my attempt at something between Scottish 80/- and Wee Heavy. Something big malty and full of flavour, without the hefty abv to go with it. So the hop bill should be tooo much of an issue, considering it was one 60min addition for around 19IBU (19 is based off my original figures) so its probably somewhere in the vacinity of 21-22IBU maybe with my reduced efficiency.

I'm using MJ Burton Union as well. so that will be interesting, not really ideal for scottish beers, but I wanted something cleaner than Newcastle, with some light fruity esters to compliment it.

I'm still holding out hope.....

[Grant R Baker]

Yeah heavy brew. Ralph mentioned that the heavy ones don't get the same efficiency.... sometime to keep an eye on and balance in BeerSmith (or whatever) as time goes on.

That said my other high gravity brews I have done lately have been bang on target (8% plus beers), I'll be brewing a WeeHeavy in Jan.

[Crusader-Rob]

The OG was supposed to be 1.063, and I hit 1.057...

I've done a couple of IPA's and missed the OG by 2 points on a beer that was supposed to be 1.066, I hit 1.064, but was 60 min boil, so I'm pretty sure its the extra 3litres being mashed without sparging, this caused my mash efficiency issues, I'm just trying to understand why.