mr_pedro Senior Member Joined: 13 Feb 2012 Posts: 31 Location: Baltimore Expertise: I love coffee
Posted Thu Feb 23, 2012, 9:47am Subject: Noob trying to get up the coffee ladder
I own a Rancilio Silvia for 6 or 7 years with a PID and since the beginning I have been able to get a reasonable espresso, it depended a lot on the coffee beans, there was one type that gave good results and all the others would produce very fast bitter shots. The last few years I have been making lots of cappuccinos in order to mask the bitterness and was happy with it. Recently I decided to give it another shot at good tasting straight espresso and it is definitely improving. Below I will describe the different stages I went through hoping it can help others in the same situation.
Until a month or so back all my doubles were coming out pretty fast, in about 15/20 seconds and there was lots of bitterness. I was using fresh locally roasted beans, my grinder was pretty much maxed out at the finest setting and the Rancilio double basket was also maxed out with the grinds almost touching the screen.
So first step was back flushing with espresso machine cleaner. Believe it or not I had actually never done it while you should do so weekly, so I ordered this little rubber disk to create a blind filter, got the special detergent and started cleaning the machine. There was lots of brownish colored water coming out of the 3-way valve into the drip tray. This made a big difference right there in reducing the bitter taste.
Next think I looked into was the brew pressure. This will be very machine dependent but all machines with a vibratory pump, like the Silvia, will also need an overpressure valve to increase the water flow from the pump during the brewing and bring down pressure to an acceptable level and have a slow enough pour at the same time. So there should be two hoses going into the water tank, one brings water from the tank into the boiler and one comes from the over pressure valve and brings boiler water back into the tank. The important thing is that while brewing you should see water flowing back into the tank. Well with the way that my machine was set up from factory, I wasn’t seeing any water flowing back into the tank while brewing. So luckily I had an adjustable valve and by loosening the bolt it could get the brew pressure to an acceptable level. To get in the ball park what you can do is put on the blind filter and measure how much water flows back into the tank in 30 seconds. This should be around 110~160 ml if you have an Ulka vibe pump. Again, the shots were tasting better, I could now slow down the flow enough with my grinder but it was still blonding very soon into the shot and producing bitterness.
So next step was to get a bigger basket, the LM style ridgeless basket. The reason for the early blonding an bitterness was that the grind was too fine, causing over extraction and bitterness. I could now start playing with a higher dose as this basket can accommodate more coffee before it touches the screen and that did the trick. While adjusting the grind to get a double in 25 seconds I was able to stop the early blonding by increasing the dose from 14 to 16 grams and now I am ready to start playing with the temperature and see what that gives.
FIVE second extractions? That's barely enough time to get the coffee wet. Whatrever works for you is fine, but if the only way you can get decent extractions is to limit the pull to five seconds, IMO, you have other problems that need to be addressed.
If it starts to go blond after 5 seconds it is not very surprising that what comes after that is bitter. But it looks like you could do much better as even a ristretto should come out slowly in 20 or 25 secs.
But if you have tried the 25 second shots and you still prefer the fast ones with channeling then go for it.
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