Monday Morning Quarterbacking/ analysis...What did I do right?

Beginner and pro baristas share tips and tricks for making espresso.
Vindibona1

#1: Post by Vindibona1 »

This past week I received a new batch of Intelligentsia Black Cat espresso beans. My other half recalled and reminded me that I had these beans some time ago and hated them. I hadn't remembered. When they came I was surpised that the beans were considerably lighter than my standard La Colombe Nizza medium roast that I have a weekly subscription for. In the past, with my Gaggia Classic and a limited amount of knowledge I've never had a good shot from lighter roasted beans and for the most part most of the bag would end up in the garbage. I've got the Nizza pretty well dialed in at 18g/36mL yield. Water flow is about 6.7mL/sec, and pressure runs between 8-9 bar. Flow control is unmanipulated.

The Black Cat seemed to be very difficult to dial in. I started with the same settings as the Nizza, knowing that it would require a lot of adjustment. The first 5 shots were undrinkably acidic and sour. Even after 7 shots, just brewed normally with 6.7mL/sec and finer grind and gradually reduced dose down to 16g, I still wasn't there. I didn't want to try anything that I didn't think was repeatable or out of left field. I was about to give up on these beans until this morning where I tried something different. I saw a video that alluded to lighter roast beans needing more "water contact time" so the shot isn't under-extracted.

So this morning, as a last ditch effort to get these shots under control, I measured 16g, ground them, did a WDT followed by distributor and then tamping. The grind was considerably finer than what I'd do with the Nizza, but grinding finer is expected. Before pulling the lever I dialed the FCD down to it's low point of 3.2mL/sec and after starting I waited for first drip and pressure to get above 2 bar before opening it up to 6.7mL. I stayed there until there were 10mL in the cup and them ramped down until I was back to 3.2mL. The total pull from lever-up was 29 seconds. While there was, of course, noticeably more acidity than my medium roast, the shot was relatively well balanced and very drinkable. If my palette were biased toward a more fruity, acidic espresso I think I'd really like it. I drank the whole thing where all the other previous shots were dumped.

Being new to a more serious approach to espresso I'm just learning and was trying to follow the logic of fixing and brewing lighter, more acidic beans. I sort of know what I did in a general sense and was very deliberate about it, planning this last pull in advance and executing the plan. So, can someone help me understand what I did right and the reason that I finally got a decent shot out of these beans?