Posted Tue Jun 5, 2012, 4:42pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
According to Illy the total solids in espresso are typically 90% soluble. So a target soluble extraction of 18-21% would imply a solids yield of about 20-23%. Does that mean further testing showed that the following line from that Home-Barista post turned out to be not quite true?
The proportion of soluble to insoluble solids in espresso may vary a lot. I would accept Illy's figure as an average of Italian espresso prepared using typical Italian baskets manufactured with indifferent quality control. (One of the design goals for VST filter baskets was keeping the insoluble solids around 4-5% or less of the total solids).
Plug for VST baskets aside, if I get espresso soluble extraction yields above ~20.5%, the shots often develop a bitter tinge. My best shots are usually around 18.5% - 19.5% solubles yield. Every once in a while a 17% shot will taste really good and intriguing -- don't ask me why!
Posted Thu Jun 7, 2012, 5:56pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
If I work a brew ratio around 18% with a pourover, and produce stuff that's 4.9% strength, I find that I tend to prefer this over same brew ratio at 5.30-5.35% - backcalculated extractions are ~19% for the former, ~>20% for the latter. When I start pushing strengths with this brew ratio approaching 5.5%, I get what you're finding - a bitter tinge and some increased astringency.
jpender Senior Member Joined: 11 Jul 2011 Posts: 722 Location: California Expertise: I like coffee
Grinder: OE LIDO Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Thu Jun 14, 2012, 9:07am Subject: Re: Coffee Extraction Discussion, Questions for the membership:
I was just thinking that if I did that and the strength didn't double, it would indicate interference or saturation due to the concentration of the already-brewed coffee TDS in the following extraction.
Well we know coffee can be a lot stronger than 3% so you're not reaching saturation. But a high enough soluble concentration could affect extraction. At some level it might be possible to drive solubles INTO the grounds. Didn't Schulman postulate that for the initial wetting of espresso pucks?
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No SEO style postings will be tolerated. SEO related posts will result in immediate ban from CoffeeGeek. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.