Grain Freshness

I don't know of any studies, but common sense says that the less time between crush and mash-in, the better. I don't roll the dice. I crush while the strike water is heating.

Here's an interesting quote from Kunze I lifted from a post by @TheBeerery.
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"As soon as the malt grain has been crushed, it is subject to oxygen uptake. Oxygen uptake during mashing in already leads to considerable oxidation reactions (Sect. 3.2.1.6)
Lipoxygenases thereby play a particular role through the breakdown of unsaturated fatty
acids into hydroxy fatty acids and other precursors of the ageing substances (see Fig. 3.44). The lipoxygenases are in the peripheral parts of the malt grain, particularly concentrated in the acrospire. Furthermore, as well as cellulose, the husks also contain polyphenols and other components which create an unpleasant bitter taste and have a negative effect on the colloidal stability of the beer."

"Through milling, the lipoxygenases (LOX) present in the acrospire are quickly activated
and at the still frequent low mashing temperatures and high pH value of the mashing water
are able to split the unsaturated fatty acids in a relatively short time and thereby produce autooxidation products, which can later lead to ageing carbonyls."

 

I also mill while the strike water is heating, and I store the grain in buckets with gamma lids until mash in. Some small breweries buy sacks of milled grain - curious to know if they purge those sacks of oxygen or not?

 

Briess discusses storing malt on their website:

“…Preground Malts are best when used within 6 months…”

http://blog.brewingwithbriess.com/about/

Cheers!

 

So, uncrushed diastatic malt is good for 6 months. And if crushed, it's still good for 6 months. Utter nonsense.

 

Write a letter to Briess since you 'know more' than they do.

 

Instead of believing everything you read on manufacturers' web sites, why don't you apply some critical thinking for a change? Is it conceivable that crushed malt stays fresh, avoiding moisture and oxidation for exactly the same amount of time as uncrushed malt? No, it's not.

Briess is very good at turning barley into malt. I don't take brewing advice from them.

 

http://brulosophy.com/2018/10/29/the-impact-of-age-on-crushed-malt-exbeeriment-results/

 

Thanks for the link. I had forgotten about that one. The experimental results, contrary to the words "indicating participants in this xBmt were unable to reliably distinguish an Altbier made using malt milled 6 months prior to use from one made using malt milled immediately before use," actually indicate that there is a 78% (p = 0.22) chance the participants detected a real difference, and didn't simply beat the triangle test null odds (1/3) by random chance. And that's with tasters of "varying levels of experience." Better tasters would, on average, tend to reduce the p-value, i.e. make it more certain that a difference was detected. Such is the nature of a triangle test designed to reject a null hypothesis of "no difference."

Sadly, anyone reading the writeup without understanding the methodology is apt to walk away thinking "here's another myth debunked." And most of the words used in the Results and Discussion sections do nothing to discourage that.

 

I agree with all of this, but I think you meant "designed not to reject a null hypothesis of 'no difference.'"

It took me a while to realize how shitty Brulosophy is. I believe it is parasitic on the hobby, leading people to make worse beer and (I assume) profiting from it. Really shameful behavior. I refuse to use the site for anything, even its less harmful output.

 

Maybe it's semantics. The experiments can reject the null hypothesis or fail to reject it.

I don't have too many major issues with the designs. But I do object to the way the results are portrayed. It would be so much better to say...

"...indicating a 78% (p = 0.22) probability participants were able to distinguish an Altbier made using malt milled 6 months prior to use from one made using malt milled immediately before use, but falling short of our significance cutoff of 95% (p < 0.05)."

… instead of...

"...indicating participants in this xBmt were unable to reliably distinguish an Altbier made using malt milled 6 months prior to use from one made using malt milled immediately before use..."

 

Oh maybe I thought you were saying something you weren't. I think the problem with the way Brulosophy does its experiments is that it presents negative results as if they demonstrate that there is no difference between the two approaches being tested. (They generally don't expressly say this, but everything about the way they present the results suggests it, and their audience predictably interprets the results that way.)

So when you said "designed to reject a null hypothesis of 'no difference,'" I thought you meant that they intentionally set up their experiments in such a way as to allow them to present "counterintuitive" results like "it doesn't matter if you grind your grain months ahead of time," gaining them a large audience but degrading the hobby. That is my view. But maybe your view is less cynical, you think they're just bad at experimental design. Plausible, although in my opinion at some point that kind of negligence/incompetence becomes culpable. It's not as though they haven't been told that what they're doing sucks.

 

To be clear, I don't have many issues with their experimental designs per se, or even with the overall methodology. I mainly have issues with the presentation of the results, i.e. no real attempt to explain what the numbers actually mean, and instead using a standard phrase (when p >= 0.05, but < 0.50) that's IMO quite misleading.

 

Maybe the hops covered up any issues. I would have tried lower Ibus.[/QUOTE]

 

Yeah, so the difference between us is that I have a cynical read on why they persist in presenting their results in such a misleading way. I think they understand that their website would be boring if it were honest about its conclusions. "Should you crush your grain as close as possible to brew day? Yeah, probably, but we couldn't prove it definitively with one underpowered experiment, and we don't do replications here. Not that kind of place." No one would buy their t-shirts if that were the kind of conclusion they wrote. Another way of putting it is that dishonesty is built into their business model.

(I also think their experimental design is often poor, but that's a separate issue and one that I think could be innocent.)

 

Perhaps the hops could have masked something to some extent. But contrary to the words in the write-up, the experiment found a 78% probability that there was a real difference detected.

 

Thoughts on refrigerating grains? Temperature probably has an effect on quality loss.

 

Personally I wouldn't do this. But if you do it, you should use the grains immediately after taking them out of the refrigerator. They are likely to attract condensation as they will be much colder than room temperature, and the moisture will quickly degrade them.