Low SG mystery in new 65 Robobrew

[Jewfish]

Hi guys
Got the new Robobrew 65 and did 2 brews this week. Great machine, but I need help to figure this problem.
First brew got SG of 1046 and was aiming for 1049. A bit down, but acceptable i thought.
Second brew, different recipie, got 0nly 1030 when aiming for 1046.
Used virtually same technique and cant understand what went wrong.
Grains in at 71 degrees. 67 degrees for 75 mins. Sparged with 74 degrees.
What have I done wrong? Is there a possiblity one of the 4 grains used in the second batch was not correctly malted and didnt release any sugars?

 

[Em Tibby]

Who milled the grain? If you - what setting was the mill?

 

[S.E]

Did you check those temps with a thermometer? Could be the Robobrew is out and needs calibrating.

 

[Jewfish]

Who milled the grain? If you - what setting was the mill?

I had the grains milled at the local brew store.

 

[Jewfish]

Did you check those temps with a thermometer? Could be the Robobrew is out and needs calibrating.

Pretty sure the Robobrew is fine as the first brew went pretty well.
Also for the boil I set the temp to 102 and it pretty much started to boil at exactly 100 degrees, so i"m confident its ok. But thanks for a great answer. I will definately double check with a thermometer on my next brew

 

[S.E]

See how the next brew goes. If it’s only a one off that happened to me once.

Turned out I had miss weighed the grain and left it 2kg short for a 50L brew length. Had me scratching my head till I thought of checking the remainder of the sack of base malt and found it.

What was your brew length and recipe? Is it possible that one of the 4 grains was left out? Did the LHBS package them separately or altogether after milling?

 

[Jewfish]

See how the next brew goes. If it’s only a one off that happened to me once.

Turned out I had miss weighed the grain and left it 2kg short for a 50L brew length. Had me scratching my head till I thought of checking the remainder of the sack of base malt and found it.

What was your brew length and recipe? Is it possible that one of the 4 grains was left out? Did the LHBS package them separately or altogether after milling?

Brew length was 75 minutes. I had 4 different grains all packed separately and all the weights looked in good proportion, but i will deffinately doulble check the weights next time. An error of a kilo or so would be a logical explanation for the low SG. Thanks for that.

 

[fdsaasdf]

If you measure gravity at the end of the mash you can make adjustments as needed; and if you check ph or measure your last runnings you can see how your extraction is going.

There are a lot of ways you can drop efficiency but any which reduce your gravity by 30% should be reasonably obvious... If I had to guess I'd say you were missing a few kilos off your grain bill in the second batch or a significant proportion of it wasn't milled properly.

How are you doing your recipe design & calculations? Have you measured volumes / deadspace and are these properly taken into account? What was your sparging technique?

 

[keine_ahnung]

Hi guys
Got the new Robobrew 65 and did 2 brews this week. Great machine, but I need help to figure this problem.
First brew got SG of 1046 and was aiming for 1049. A bit down, but acceptable i thought.
Second brew, different recipie, got 0nly 1030 when aiming for 1046.
Used virtually same technique and cant understand what went wrong.
Grains in at 71 degrees. 67 degrees for 75 mins. Sparged with 74 degrees.
What have I done wrong? Is there a possiblity one of the 4 grains used in the second batch was not correctly malted and didnt release any sugars?

If I understand this correctly, you're dropping the malt into 71deg water...??
If so, that's a massive shock for the enzymes. Especially the ß-Amylase. It's deactivation temp is 70deg...and that's sensitive and irreversible.
I've used this analogy before, but imagine if someone threw you directly into a pool at 71deg. You'd shrivel up and scream and denature.....just like enzymes do if they're hit with sudden heat.
Enzymes are simply proteins with special abilities. To get a bit of an idea how proteins react, take a look at this video:
It's not actually a brewing video, but I found it very helpful to get my head around the complexity of proteins, which is very important if you want to truly understan the complexities of brewing.

Below is a graph to help understand the behaviour of enzymes vs temp. Note: this is for the ß-Glucanase. The ß-Amylase is very similar, just shifted to the right a few degrees.
Translation for the comments below the graph:
1. Reaction-speed increases with increasing temp with a factor of 2.3x / 10°C
2. Once the "optimal-temperature" is reached, the enzyme is quickly irreversibly denatured.Enzyme-Activity then falls rapidly to 0.

As already touched on, mill-settings and sparging also have a big effect on effeciencies.
Is there a reason you sparged at 74 instead of the usual 78deg?

 

[brewermp]

If I understand this correctly, you're dropping the malt into 71deg water...??
If so, that's a massive shock for the enzymes. Especially the ß-Amylase. It's deactivation temp is 70deg...and that's sensitive and irreversible.
I've used this analogy before, but imagine if someone threw you directly into a pool at 71deg. You'd shrivel up and scream and denature.....just like enzymes do if they're hit with sudden heat.
Enzymes are simply proteins with special abilities. To get a bit of an idea how proteins react, take a look at this video:
It's not actually a brewing video, but I found it very helpful to get my head around the complexity of proteins, which is very important if you want to truly understan the complexities of brewing.

Below is a graph to help understand the behaviour of enzymes vs temp. Note: this is for the ß-Glucanase. The ß-Amylase is very similar, just shifted to the right a few degrees.
Translation for the comments below the graph:
1. Reaction-speed increases with increasing temp with a factor of 2.3x / 10°C
2. Once the "optimal-temperature" is reached, the enzyme is quickly irreversibly denatured.Enzyme-Activity then falls rapidly to 0.

View attachment 114527

As already touched on, mill-settings and sparging also have a big effect on effeciencies.
Is there a reason you sparged at 74 instead of the usual 78deg?

Not that I’m disagreeing with science but this is a common practice to make your water slightly higher in temp than your target mash in temp to account for the drop in temp when you put your grain in..

 

[Wobbly74]

I can say that isn't the problem. I recently did a mid strength pale ale, strike water at 72.8C, mashed at 70C and got 85% mash efficiency and 75% BH efficiency.

 

[S.E]

I normally mash in between 71C - 73C. Can’t remember the last time I went lower than 70c.

 

[S.E]

Brew length was 75 minutes. I had 4 different grains all packed separately and all the weights looked in good proportion, but i will deffinately doulble check the weights next time. An error of a kilo or so would be a logical explanation for the low SG. Thanks for that.

Sorry didn’t see your reply yesterday for some reason.

Brew length is the amount of beer brewed. Commonly known as batch size these days.

So if your brew length/batch size was 50L for instance you would have had to be about 3kg short of grain which is why I was thinking the LHBS may have forgot to pack or mill one of your four grains but if they were all packed separately you’d have noticed.