# Sudden milk separating acidity



## mbenney (Apr 18, 2020)

Hey guys,

Hoping for some advice with a problem I've suddenly developed.

Set-up: Rancilio Silvia v6, meCoffee PID set at 105 deg, Niche Zero, Volvic

I had been getting really nice, consistent results with Redbrick seasonal espresso and Square Mile Decaf espresso with a 16g dose and 2:1 ratio.

I decided it was time to try a VST 18g basket.

So upped the dose to 18g and stuck with a 2:1, 36g yield.

The results:

Redbrick seasonal: Insanely thick mouthfeel, increased sweetness, pleasant acidity
Decaf espresso: Thick, but super acidic, not nice, causing the barista Oatly to separate in a Cortado

Finished the redbrick and moved onto Rave signature and this is also coming out too acidic, though drinkable in a Cortado.

Plot twist... I went back to stock basket and 16g dose while I do some more research. But with all other variables, as far as I can see, the same, the decaf is still very unpleasant and separating the milk. It's the same bag I've had no problems with previously, and is about a month from roast date. The Rave seems pretty acidic too. The rave is pretty fresh, just under a week from roasting.

Any idea what could be happening?

What should I be adjusting to get back on track?

Note, I've struggled a bit with sourness in the past, and I don't taste this as the same. It's very full bodied.

Thank you... every time I think I'm starting to know what I'm doing, I get reminded I know nothing 🤡


----------



## Mrboots2u (May 10, 2013)

We're you using oatly prior to this .

how old is the coffee , overly fresh beans can cause bubbles in the milk.

I use SQM decaf as my go to in an 18g basket , never find it particularly acidic on its one or cows milk .. it's not a light roasted hard to extract bean , does need a finer grind than normally red brick. 
Vst need a finer grind , caveat at the same dose , than a stock basket , it your not helping by jumping from a vst 18g dose to 16 g stock basket .

using the vst I'd try down dosing a little to 17 or 17.5 g making sure you have enough head room in the pf, by doing the coin test .

dose and tamp , stick 5 p in puck lock in , take our , of coin is creating dent , reduce dose

silvias have less headroom that a lot of other machines ,


----------



## mbenney (Apr 18, 2020)

Thanks for the reply Mr B.

Yes I've always used Oatly and it has been great.

This new problem I've had over an older carton and a brand new one.

The sq mile decaf is roasted Oct 01 and I was having good results with the same bag with 16g in the stock basket, and on the same grind setting (I keep a log in a notebook.

I've always had puck indentation with Silvia with 16g in the stock basket but it's never caused a problem before.

I've found going from stock to VST, 16 to 18 has needed more or less the same grind, but I guess the updose accounts for this.

Cheers


----------

