jpender Senior Member Joined: 11 Jul 2011 Posts: 535 Location: California Expertise: I like coffee
Grinder: OE LIDO Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Wed May 16, 2012, 1:00pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
The thing is, it doesn't even matter what the absorption constant is so long as it matches the brew. That's why it's an input parameter in the Mojo software. Except that they use a different definition. Their "water loss" in g/g is basically your absorption constant + 0.2. So if the grounds are absorbing 2.0 g of water per gram of initial grounds then that's approximately the same as your choice of 1.76.
If I were using Mojo for my brewing I would input a lower number as I almost never see anything close to 2g/g of water retained in the grounds.
The apparent linearity of these results could be a coincidence.
If higher brew ratios (lower temperature profiles) result in lower effective extraction AND the grounds liquid is actually something less than full strength coffee then you could get a result that looks like the grounds liquid is full strength when it isn't.
For example, if the brew ratios are 6%, 12%, and 18% and the strengths are 1.3%, 2.6%, and 3.9% it looks like the grounds liquid strength equals the cup strength. That would imply an effective extraction (all the liquid) of 21.7% for each of the three brews. They might taste "okay".
But what if the strength of the grounds were actually only 50% of the cup strength? Then the effective extractions would be 20.8%, 19.8%, and 19.0%. These might all taste okay too.
The problem is that we don't know if our lone taster can reliably resolve differences of this magnitude. If he can only say "underextracted", "okay", "overextracted" with certainty it leaves a fair amount of wiggle room.
I'm not sure that your presciption for adjusting the temperature makes sense. I've spent a little time recording Aeropress temperature profiles and the concept of a "hit" temperature as a way to guarantee equal extraction profiles seems like a reach to me.
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 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.