Always a good topic this one Aamcle .

Firstly, there are virtually no side by side controlled experiments ever done in brewing as pretty much no one has the ability to do side by side experiments. I do have that ability and have done this experiment over six side by side double batches - that's about 60 gallons of beer and I will never do it again.

So, first problem is that almost no one has two identical sets of equipment where they can brew simultaneously and literally side by side. The second problem is that because of this, most side by side experiments are done once and on a very small scale. I've never seen one repeated six times let alone on the scale above. Large breweries have some ability to experiment because they are brewing the same recipe over and over again. That is the closest you will get to side by side experiments in the real world.

In my experiment of full volume mashing versus sparging, there was only a 1% difference on average on sugar gained (kettle efficiency). The sparging method had an additional advantage in that the grain 'saw' water for longer. In the experiment the mash was done for 90 minutes on both methods.

Understanding This

This is a very difficult thing to conceptualise because we are brought up in a world of washing machines and we think that rinsing is necessary to get things clean. Below, I'm going to try and give you a few different ways of thinking about this...

Sugar dissolves in a relatively small amount of water. If you have two sugars in your coffee, do you add water to your sugared coffee in two hits or just one? We all know that it makes no difference so we always add it in one hit. In fact, no matter how you add the water, you will always end up with a cup of coffee with two teaspoons of sugar. Let's try and get a bit closer to brewing though...

Let's put those two teaspoons of sugar inside a tightly meshed "tea bag". In other words, it will take time (say 90 mins) for the sugar to leach out through the "tea bag" and into the water. Is it better to add all the water at the start or add it in several hits? The basic rule of osmosis will tell you that it is better to add all the water at the start. At the end of the day though, the multiple additions will catch up top the full volume addition if given enough time.

...

Another way of looking at this is thinking of hand-washing very dirty clothes in a bucket of water. In fact, imagine saturating your jeans in a really sugary liquid. Leave them out to dry and now try hand-washing the jeans in two 5 gallon buckets or one 10 gallon bucket. The end result will be the same. Your jeans will not come out totally clean. In fact, whatever method you use, they will come out with the same amount of sugar clinging to them.

....

The difference between washing clothes in a washing machine and brewing is that your clothes are much 'cleaner' than your grist. It is not the same scenario. It is space, timing etc that has lead to commercial brewing being done in several vessels. It isn't one of sugar extraction efficiency.

So, be comfortable in your full volume or SMS (simultaneous mash and sparge) brewing.


PP

P.S. "I obtained about 86% mash efficiency on my last two batches." Your kettle efficiency (what BF is calling 'mash efficiency') should actually vary depending on how strong or weak a brew you are doing. This is the beauty of the BIABacus compared to other software. Other software leads you to believe that you will get the same 'efficiency' on every brew you do. This is incorrect. Instead, the BIABacus looks at how dirty your clothes are and then says, "I think we can get them this clean." See the paradigm shift?

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Aamcle,

I brewed today, FVM with a squeeze no sparging and according to Brewers Friend I got about 80% mash efficiency a bit down on my last two batches.

Was this the same beer that you brewed with 86% efficiency on two batches in you first post?


PP wrote

Your kettle efficiency (what BF is calling 'mash efficiency') should actually vary depending on how strong or weak a brew you are doing. This is the beauty of the BIABacus compared to other software. Other software leads you to believe that you will get the same 'efficiency' on every brew you do. This is incorrect. Instead, the BIABacus looks at how dirty your clothes are and then says, "I think we can get them this clean." See the paradigm shift?

Some eye opening statements PP! Your short PS really helped me understand a few things!

Trout

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PistolPatch wrote:Always a good topic this one...

And one that can't be quickly skimmed through . (aamcle, re-read my last post slowly because you have definitely missed some very important stuff . Trout picked up on one above).

Here's some more things....

Q. I'm confused on the squeezing. When you are sparging are you not squeezing before you tansfer the bag? Or are you not transferring the bag at all, just adding more water (hot/cold) into your system after your mash ends? It's really important to give a lot of detail because what you think is obvious to everyone else might not be. I'm only just now picturing what you might possibly be doing but I still really have no idea.

Q. Regarding detail, your last post gives nowhere near enough. Was that 4.25 kg of Golden Promise mashed in 100 litres of water or 30 litres? What were the other brews mashed and sparged in? What was their OG?

Q. How many times did you measure your volume and gravity? Did you do it pre and post boil? (A single measurement on a single brew can never be trusted. In fact, you need to do several measurements over several brews...)

When measuring you must commit to doing several brews that are as identical as you can get them. That is why I did six side by sides and took many measurements just to determine the answer to the question you have asked. Look at my results and you'll see that any single measurement is not trust-worthy. OPn average though, they tell the tale.


PP

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Gotcha, yeah we're probably just confusing each other at this point. What I was picking up from you, is that you got 86% on two previously sparged brews. The most current, which is a different brew altogether w/ FVM ... you got 80% on. It seemed implied you were dissatisfied with a 6% drop, which to me ... is perfectly normal for a different recipe.

I'm thinking the lack of details from the three subjects are causing the most confusion, because I'm sitting here trying to fill in many, many blanks. If I had all of the information, I might see what you were trying to convey here.

Anyway, I do not bother squeezing ... as you say it's a lot of trouble. I hang my bag of grains over the kettle while heating to boil (after ramping to a mashout temperature) ... haven't had issue hitting my predicted volumes at all.

FVM, mash out, 90 minute boil (mainly so I start with more water), no squeeze ... works for me. No effort whatsoever beats dunk sparging for me!

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Okay, I'm beginning to see a few things...

I really need my first question asked above answered but from the last few posts am assuming that you are leaving your bag in the kettle and just pouring water over it??? (Many brewers who aren't FVM are squeezing their bag and then moving it to another vessel where they are sparging which is really 'expensive' in labour, vessels etc. From what I am guessing, you aren't doing this.

Squeezing and Bag Porosity

I recommend a quick squeeze so as the bag can be removed from the kettle without it dripping everywhere. However, even this advice is fraught with differences in people's set ups. For example, Rick might have a relatively porous bag (like my first BIAB bag) and normal crush which might drain easily and quickly. In other words, he might find he has to give no squeeze for it not to drip. A very fine bag however can take ages to drain and, even with squeezing, it can retain a lot of liquor. This is why it is so important to give detail on your system. method and equipment.

The above though is actually not relevant though. In this thread we are asking the question, "Is FVM any more or less efficient* than mashing followed by an active sparge/s?" You could squeeze or not squeeze the bag in FVM (passive sparging) or in active sparging. What is important is that if you are comparing passive and active sparging, that you do the same for each method.

[* Nothing wrong with using the word efficiency as long as you define it as being a kettle or fermentor efficiency. "Kettle efficiency" is based on the volume and gravity of the wort at any time during the boil assuming the volume is adjusted (shrunk) back to ambient. Multiplying it by 0.96 is good enough. Hopefully, Brewer's Friend's 'Mash Efficeicny' also means this. If it says 'mash efficiency' then it should.]

The Sponge and Where We Get Confused

The analogy of the sponge is a good one and we have used it here before however, it applies just as much to traditional brewing, dunk sparging etc as it does to pure BIAB (full volume mashing). In all methods, the grist acts as a sponge. One advantage of BIAB is that you can actually squeeze the sponge easily whereas in a traditional mash tun, it is not easy and you will find that almost no one does it. Let's forget about squeezing though (as mentioned above, it is irrelevant) and look at the sponge analogy a little deeper...

Let's assume I have a sponge that I have dipped in red food colouring and then squeezed to buggery. Let's think of this red sponge as our grain full of sugar. I can then 'mash' (soak) it in water. Let's say I have a 70 litre (about 15 gallon) bucket available to me and I have been told that I can use a maximum of 10 gallons (a bout 50 L) to wash (soak and rinse) the sponge in. I can either use 5 gallons to soak and 5 gallons to rinse or 10 gallons to simply soak.

If I soak with all ten gallons and then drain the bucket, let's say the water will be 9 gallons @ 10 units of redness = 90 units of redness. (The sponge has retained 1 gallon at 10 units of redness.) If I soak the sponge with 5 gallons and drain the bucket, the first draining will be 4 gallons of @ 20 units of redness = 80 units of redness. (The sponge has retained 1 gallon at 20 units of redness.) I then follow with another 5 gallons, let it soak for a bit to leach what redness the sponge still has left out but, even still, this will only yield 5 gallons @ 2 units of redness = 10 units of redness. 10 + 80 = 90. (The sponge still has retained 1 gallon at 10 units of redness). In other words, both methods are the same.

The above paragraph is the first thing to allow into your mind and ponder.

....

Another way to look at it is this. In scenario A above, after the mash, the sponge is twice as clean as the sponge is in scenario B. How much more water would you need to hose sponge B with to get it as clean as sponge A? The answer is a lot and this is where the problem lies....

In our thinking, we tend to think that a sparge flushes out all the sugars and replaces it with clean water and this is a very natural way to think but it isn't like that. A sparge is actually a lot more like pouring water over a dirty sponge - you actually will need a tremendous amount of water to clean it especially if you don't squeeze the sponge. Or, if we go to an extreme, how many litres/gallons do you need to get a paint brush clean? 1 gallon or 10 gallons?

Summary

A full volume mash and a quick squeeze is going to serve you really well in not only grain efficiency but labour and equipment as well.


PP

P.S. Just when I though I couldn't think of another analogy and the paint brush pops into my head .

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Nice to hear back from you aamcle.

Look, this whole area is not a black and white area.

Maths, in this scenario can prove a low volume plus sparge/s versus a full volume simultaneous mash/sparge to be either more or less efficient depending on the model / reasoning used.

There are so many factors that come into play here though. The best 'starter' summary of factors I can think of though is...

Efficiency into Kettle increases with:-

1. A sensible crush.
2. Grist's contact time with liquor.
3. The 'overall' liquor to grain ratio.

That is just a 'starter' summary. Many more factors come into play but I think I have nailed the most very basic starters here. If not, add them below please.


PP

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Side by Side experiments?

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