FG question

[Doctormcbrewdle]

I have a good mate who's relatively new to all grain brewing and struggling to hit expected fg. He's coming out around 1.015 every batch

I've just discovered though that he's heating to mash temp 66 then turning flame out and adding grain.. I'd expect the temp to drop to around 61 right after and drop even further over the course of an hr (this is just a guess and could be lower or higher depending). for the start of mash. Is this likely the reason for high fg? Possible too low to convert and leaving a portion of unfermentable dextrins behind?

Cheers

 

[MHB]

There is as they say "more than one way to skin a cat" any way you chose - still sux to be the cat.
There simply isn't enough information to give an exact and guaranteed right answer.
Lots of things affect what happens in a mash and ferment, there are a couple that he will need to make sure of.

First is the temperature, has he stirred the water, its can be 66 in one place - hotter or colder in others.
How good is his thermometer, I've seen some that are 20oC out, invest in a decent lab grade thermometer, also worth noting that thermometers come in two common types, Total immersion (stick the whole thermometer in) and 76mm immersion (only stick 76mm in) there can be 2-3oC difference caused by using a good accurate thermometer the wrong way.

Mash temp, 61oC is too cold for the whole mash, that's close to the Beta Amylase peak, but on its Beta is very slow, a better mashing temperature for Isothermal Mashing is around the 65-67oC. Mash in around there - use a calculator to get the strike temperature right - insulate the tun well, an old beach towel is enough but there are better options..

L:G Low Liquor (water) to Grist ratios will reduce the fermentability, I would think about 3:1 is a minimum,

Conversion time, Mash for at least 1 hour, shorter can cause problems

Sparging, Sparge slowly or if batch sparging more smaller sparges is more efficient.

Water Chemistry, Not really likely to be a problem unless the water is very soft or extremely hard, always worth adding a bit (50-100ppm) of Calcium, it helps enzymes work better (do more conversion) helps lower the pH in to the optimum range, helps with Trub formation and even helps the yeast.
If you he is using tap water - well most water is fine in Australia, but a bit of Calcium will help

Yeast, the amount, the fermentation temperature, the type of yeast, how long its in contact... A good healthy yeast pitch at least 11g (one of the common Safe/MJ/Lavin...) will solve lots of brewing problems.

Step one is to calibrate his thermometer, get the mash temp right, have a general look at his process (at need keep notes - good ones, step by step and all the amounts of ingredients (brewing is all about Quantities and Conditions)) and come back - ask more questions.

Hope that helps
Mark

PS
20 years running a HBS shop - you wouldnt believe how often the answer is a cheaparse inaccurate thermometer, always have a good ($15-20) calibration thermometer. Wrong place to be a tightarsed f/whit!

 

[Doctormcbrewdle]

That's a great answer Mark, thanks! I was going to mention maybe try another thermometer but didn't think there'd be much diff. Definitely will mention it now

 

[MHB]

In my experience up there with hygiene, ferment temp control and not picking your nose in public..
Everyone should have 1 good thermometer they can trust and reference from it. Spend the money, avoid Chinese ones think UK or French my LHBS stocks a very decent Ella for $15 (IFIRC) - think of it as an investment in every beer you will ever brew!

That mash temp of ~61oC is way too cool - you would do a very long mash at that sort of temperature to make extra dry type of beer, to be mashing that cool and still finishing at 1.015 makes me think he isn't - mashing at 61oC I mean.
Mark

LHBS is Brewman - hasn't got them listed on the site - I will be there later today and will see if he can put them up.
M

 

[Doctormcbrewdle]

Thanks again Mark. I'm using a chinese digital Ebay special.. and he has an old school glass type. I'll definitely check out Brewman' site over the coming days and pick one up!

Ps, he's just confirmed it was a cheap one. I'm also thinking it's possible like you said that he's mashing too high at 70 odd. That would make sense

 

[Matplat]

You can also 'calibrate' the thermometer by using iced water, and boiling water as reference points.

A known good thermometer is better, but until you get one, these reference points will help.

 

[Brewman_]

Added to the site

Thermometers

Cheers Steve

 

[Aksarben]

Also do check the yeast. Some are much better at getting a lower FG than others.