Thanks rmachado for the info on the hop and yeast measurements - that's great.
If you want to go the hop slurry route, I would wash it. I managed to use US-05 for over a year with that technique for over a year (and then I let a friend use my gear and replace the yeast

). I'll give more info on washing if you need it but I'm thinking a search of "wash" or "washing" of posts done by me might help me be lazy

. (Not sure on that so if you can't find anything, let us know).
rmachado wrote:The 60-90 min mash are calculated in the BIABacus formula?
I´ve done some test batches with different mash times, as short as 30 min and planning a 15 min mash. What do you think of this? (with a high mash temperature in mind, around 68 C )
The existing BIABacus formula will not change whether you type in a 1 minute mash or a 1000 minute mash. A 90 minute mash though should get you achieving above the estimate and a 90 minute mash versus a 60 minute mash will, on nearly every type of grain bill give you a higher kettle efficiency based on the numbers collected in
this thread.
That thread proves that things like iodine tests etc, cannot be relied upon and that pre-boil gravity, on most recipes, will improve given the extra 30 minutes. So, there is no doubt there is an 'efficiency cost' but what we don't know is what the quality cost is...
"Older" brewers (not age but number of batches) like ShorePoints and myself tend to just be happy with the 90 minute mash as it is definitely the safest method. I, personally have done so many side by side experiments (not in that area) that I end up making too much beer so I am over experimenting for a while!!!
This doesn't mean you can't though.
Here's some problems with experimenting to be aware of...
1. Most home brewers can't do side by side brews but that is the most reliable way of experimenting.
2. Even if you can side by side, on most types of experiments, you still need to repeat them a few times.
The above is rarely ever done and, what worries me, is brewers who have not even been able to do the above, often publish 'official' results and draw conclusions based on two batches separated by time.
That's a big problem

.
I taught thinking skills for many years and probably the only book I liked of Edward de Bono's was, "I am right, you are wrong." In that book, he talked about the tendency of western minds to think only in black and white, yes/no, 100%/0%. I think we see a lot of that in home-brewing experimentation. Here's one example...
If you did a full-volume BIAB mash for 60 minutes versus a traditional 60 minute traditional mash followed by sparging, you would, on most grain bills and equipment set-ups, get a higher kettle efficiency on the latter method. Many people would conclude that the latter method is more 'efficient'. But, if they extended the full-volume BIAB mash to 90 minutes, they would come to an opposite conclusion. (Given everything else is the same, it is time that increases kettle efficiency.)
Now, imagine the above scenario again but on the first brew, the brewer brewed a 1.060 OG brew on a 60 minute full volume BIAB and on the second, they mashed for 60 minutes and then sparged a 1.050 OG brew. The latter method would again show a higher kettle efficiency. Given the software around, the new brewer will assume that "traditional" mashing and sparging is moe efficient than full-volume brewing whereas the truth is the reverse.
The truth in the above is that it is contact time with the grain that makes the difference.
So, your proposal, "I´ve done some test batches with different mash times, as short as 30 min and planning a 15 min mash. What do you think of this?" is basically one where you are reducing contact time with the grain. We know it will cost you in efficiency and, as I said above, the quality is the unknown factor.
In your situation, doing "tiny" batches, I think it will be great to hear how you go but very hard to draw conclusions - an extra ball of dried yeast or a slight mis-measurement of hops could possibly make a big difference on tiny batches. But, let's go beyond that...
Let's say you had two systems like I do and could do two "double-batches" (say 38L or 10 gal into packaging) side by side and, after doing it twice, still noticed no difference between a 15 minute versus 90 minute mash, then we still have to answer the following questions before we can recommend the process:
1. Is there a problem with the "shorter-mashed" beer that you are not aware of? For example, I can't stand acetaldehyde but lots of my brewer mates can't taste it. The same guys complain about diacetyl and I still don't know what that is!
2. Let's say you did the above on a low-hopped lager. Will you get the same result on an IPA?
I've spent a lot of thought, money and time on just a few experiments, making sure the conclusions are correct. It's tedious, expensive and time-consuming to experiment properly. These one-off experiments, almost always, don't tell you anything,
but, but, but...
I really encourage you to experiment, especially on this forum, no matter your batch size. All experiments start with a hypothesis (if my memory of school is correct). If your experience results in a hypothesis such as, "I really don't think there is any difference in a 15 minute mash versus a 90 minute mash quality-wise when brewing
x style," then we do have the resources here to side by side stuff like that.
So, jump into it and let us know how you go

,
PP