Should you sparge cold brew?

[Owly055]

Since I quit brewing beer, I've done numerous projects. I make cheese, bought a kamodo grill, and am using it for grilling and smoking. I bought an Omega 900 auger type juicer to get more and broader based nutrition, as I've never eaten enough veggies. Also a dehydrator, (LEM brand) which I use in numerous ways from drying fruits and veggies to drying my juice pulp to grind and use in baking, to making jerky, etc., I'm working on constructing a sailing trimaran built from a 17' canoe, and two Hobie 14 hulls.... The idea is to have two narrow side decks each a bit over 6' in length, that slightly overlap into the canoe.... for sitting and sleeping.... It's to be a camper for large inland reservoirs.
I seem to be obsessive about projects ;-)

I'm about to try making nitro cold brew with a Krone nitro faucet I've had for awhile. I'm using a 1.75 gallon keg, of which I have two...... They sit on the top shelf of the fridge perfectly. The other has either carbonated water of kombucha in it usually. I wanted the tap on the keg, and it had to be low profile. I started out with a piece of angle iron, which bolts to the keg handle using an existing hole. It has an end that touches the top of the keg, and I welded a tab on that prevents it from being able to rotate forward, thus it cannot move in any direction. However the keg handle is very light material and flexes. To solve that issue, I made a thin metal plate that you can see in the photo just under the hose. It tightens down under the liquid out coupling, which I ended having to modify slightly........ by removing a bit of material along the bottom so it would screw down enough. I did this in the drill press, removing the O-ring, and tightening the tap in the chuck, turning the drill press on, and using a small grinder to take it down a suitable amount. As you can see, I removed the stud from the tap handle....... It would not quite fit in the fridge, then drilled a piece of steel to attach horizontally, with a piece of wood dowel screwed on top. This fits. It was a royal ***** removing the stud.... It was secured with red locktite.... a bit of persuasion with a hammer, and lots of force, finally broke it loose.
The kegking as a short stub of stainless steel pipe on the gas in port, and I was able to attach a plastic hose to it after softening it in hot water so it would stretch. On the other end of the hose is a sintered stainless steel carbonation stone.
In the photo, there is water in the keg, and I'm using CO2, which I ramped up a little bit at a time to encourage full carbonation. The bottle is one of several paint ball bottles I bought for carbonating.... an excellent solution. I have a reasonable size nitrogen bottle that I will use with the coffee.

Questions:
1: Should I use any CO2, or just Nitrogen? With stout, you carbonate to a low level, then drive it through the stout faucet with higher pressure nitrogen. Liquids do not take nitrogen into solution nearly as easily as CO2, but I'm not sure carbonation makes sense.

2: I sparged my cold brew, which I did BIAB, and am currently filtering it through coffee filters. Was sparging a good idea of a bad one?

 

[punkdigerati]

Aloha,
I recommend only using nitrogen, CO2 will sour the coffee.

I have only done a single coffee sparge experiment, so it could have been other variables, but I recall it being overly bitter. How did yours taste?
In theory I think sparging would allow you to get the coffee that is being held by the grounds, but it's also possible that you will extract components you were trying to avoid. I'd love to hear if yours tasted good, and plan to experiment more myself.
If it isn't great, the next best way to minimize lost coffee to the grounds is to brew at ready to drink concentration. Caveat, this works best for nitro cold brew because you can purge the oxygen from the keg, RTD strength cold brew doesn't last long if it's getting oxidized, unlike cold brew concentrate which will last a week or two refrigerated.
I plan to experiment with using nitrogen to push the remaining bound coffee out of the grounds at some point, as well as trying recirculating the water during brewing to possibly shorten the brewing time.

I find my best results for nitrogenating cold brew come from using a carb stone in the keg, either with a carbonation lid or on the dip tube. I keep the gas on through the carb stone the entire time I'm dispensing, though the last pour is foamy. You can also shake the keg under pressure, but it can take a while to get nitrogenated. I usually pour at 35psi through the stout tap, and force nitrogenate overnight at 50-55psi.
It's possible it's overkill, you might be able to get away with wasting less gas than me.
I often use a 1 gallon mini keg, with a special ball lock head, and don't always have the gas hooked up when I'm dispensing, and it creates a fine cascade even under just head pressure, but not for the entire keg, unless I underfill and overpressure.