Inconsistent roasts

[Gretsch]

I back flushed the machine on Monday and gave it a clean before we went away for the week. I emptied out the grinder and washed the hopper as well. I ran a dose of puly grind crystals through it in early January and figured it won’t need another dose yet.

This morning I got the scales out and measured the dose which is consistent at around 14g so the grinder seems to be doing it’s job well.

I give the machine a good 25 minutes in the mornings to get it up to temperature.
I place the portafilter underneath the holder and flush out anything, then wipe it dry.
if the water gushes out under pressure I’ll let more water out to get the temperature down a little.
If the heater comes back on I’ll give it some time then switch it off. What happens is the thermostat will cut out as the water temperature equalises, then I turn it back on for the shot. That’s how I temperature surf (if that’s what it is).

I dose out 1 shot into the portafilter at 7g, knock it down on the bench, dose out a second 7g, knock and tamp firmly.
1st shot I pull is 70g of coffee, 30 seconds (for the one that must be obeyed) 😏

Second shot today was 39g, takes about 15 seconds for myself.


Today, tasted ok. 👌

Decided to pull a second shot half an hour later (14g/39ml 15 seconds) and I can taste a little bitterness this time 😳

I don’t leave the machine on all day, occasionally we’ll have another shot later in the morning so I’ll switch it on and go through the same as above.

[Gretsch]

Thanks for your help, when I get back home Thursday I’ll make changes as your suggestions and report back.

[saeco_user]

Reading your previous posts again, and noting that you have a Silvia, unless you are "temperature surfing" there can be quite a large shot temperature variation, resulting in some bitter flavours. But do make sure your dose is consistent (as above) before trying to troubleshoot the rest of the process.

[saeco_user]

If consistency is of issue the first thing to do is literally weigh the grounds before each coffee and ensure a consistent amount. What you think may be about 16g may have a larger variation than you realise. Secondly make sure you a using freshly ground beans each time. Some grinders retain 2-5g (or more) of coffee in the chamber and chute. If this has been sitting there for a day and is included in your dose it can make a big difference compared to a full dose of freshly ground coffee. You can only have a consistent output if you have a consistent input.

[Rami]

What’s your end weight? Time seems ok, there is a large variance in time, as long as it’s not widely out it’s ok.

extraction time variance says puck prep to me. Maybe you have channeling? That’s why a naked portafilter helps.

as coffee grows more stale you will have more extraction than fresh coffee. So I tend to grind finer as I get to the bottom of my bag to compensate but this is over a couple of weeks, not days.

ps. I had issues with 16gm starting weight as Small changes in weight threw me off. At 18/19 gm a 0.1/0.2 variance had little effect. But that may be my set up. the 35 sec is normally for a 20gm dose

[Gretsch]

Well I got that wrong! I thought it was timed for the actual coffee volume.

I’ve been dosing around 16g of coffee and extraction time is around 20 to 25 seconds from the time I hit the switch. Extraction times vary considerably from day to day 😳

[Barry O'Speedwagon]

It's not 30 seconds for 30ml. It's 30 seconds for 30g (or so). 30g of brewerd coffee will be more like 45-55ml (including crema).

[Rami]

Mate. Use grams not ml. Also use a naked portafilter.

what is your starting wieght?

[Gretsch]

Yeah right, understand that, and it’s something I struggle with. To achieve 30 seconds for 30ml of coffee the machine chokes. Anything close usually results in a very strong, bitter coffee.

[Barry O'Speedwagon]

Very roughly......'Dial it in' refers to the process of adjusting the grind setting such that (for a given dose) you are extracting (very) roughly 1.5-2 x the weight of the ground coffee, in about 28-35 seconds. So if you usually put 18g of ground coffee in the portafilter you might pull 30-36g of brewed coffee in roughly 30 seconds. YMMV. More generally, it simply adjusting the grind setting to get the result you're looking for.

The 'brew ratio' is the ratio of ground coffee to brewed coffee described above. Hope that helps (rather than hinders )

[Gretsch]

I don’t understand “dial it in” or “brew ratio”.
Beans are stored in a vented coffee zip bag for a week in a dark pantry before I put them in the hopper and I cover it with a microfibre cloth to keep the light out. We live in a house with lots of glass.

[Rami]

Dead right and come to think of it, I can justify that.
My next door neighbour just so happens to be a coffee farm. I've had beans from them where we've sampled them on their commercial machine, I've taken the same beans home, put them in my Silvia -- on the same day, and a totally different taste! Nowhere near as good.

ah!

first question.

did you dial it in properly? Did you get the same brew ratios?

each machine is different, but if you get the same brew ratio you can at least have a like for like comparison.

Sound like prep/brewing, even badly stored beans would not change that quick

[Gretsch]

Mate, what you are describing is an inconsistent brew. You should not be getting 3 different coffees from the same batch at the same time. I am thinking brewing, prep or storage.

Dead right and come to think of it, I can justify that.
My next door neighbour just so happens to be a coffee farm. I've had beans from them where we've sampled them on their commercial machine, I've taken the same beans home, put them in my Silvia -- on the same day, and a totally different taste! Nowhere near as good.

[Barry O'Speedwagon]

Yes, sorry. I typed M2M by habit. But the general point is the same. If you load up 3 coffees worth in the grinder, the first two will grind with plenty of beans above the grinding chamber. The last one will grind a little differently (which is fine if you always 'single dose').

I still see no reason to suspect the roast at all.

Do you leave the Silvia on all day?

[Rami]

Mate, what you are describing is an inconsistent brew. You should not be getting 3 different coffees from the same batch at the same time. I am thinking brewing, prep or storage.