60mls Senior Member Joined: 22 Dec 2003 Posts: 84 Location: Melbourne Australia Expertise: I love coffee
Espresso: Expobar Barista Minore Grinder: Mazzer Mini-E Vac Pot: Bodum Electric Santos Roaster: Billy Can drum
Posted Wed Jun 2, 2004, 3:48am Subject: Fast beans, slow beans?
Hi all,
I was reading once (probably here), about combining beans to reduce the number of batches required to blend. Someone said that you can preblend the fast beans and roast, then problem the slow beans and roast. From memory the fast beans were Brazils & Ethiopians.
What is the determining factor that makes a bean slow or fast?
Hi Ed... Slow and Fast refer to how quickly beans respond to the profile of the roaster. Below is a quote from Jim S which talks about fast beans...if you know the fast ones, it helps determine the 'normal' ones! I have grouped beans this way, but with just FR+ it is just as easy to not group them. However with your 'Billy Can' (not sure what that is) if it is larger capacity, then segregating and roasting slows and fasts would be a good thing.
One of my complaints with preblends is that when the fast beans are in a near rolling 2nd the laggards are barely City Med-Full.
Fast beans: Brazils, Yemen and dry processed Ethiopian, Aged Indos and Monsooned Malabar, low grown Island Beans (not Yauco, Kona, ISH or JBM, but the cheapies).
Posted Wed Jun 2, 2004, 7:18am Subject: Re: Fast beans, slow beans?
There is more than one reason why some beans roast faster than others but generally speaking, two of the main factors are the moisture content and bean density. There are also different sources of moisture inside the bean: there is moisture bound in the carbohydrate molecule itself, but the moisture that most affects the roast is the partially free moisture, most of which evaporates in the first stage of roasting before and during first crack. The more moisture contained in the bean to begin with, the longer it takes to evaporate (or the more heat it needs). The first portion of the roast takes the moisture from its initial content - typically anywhere from about 10 percent or less to 20 percent or more - down to about 2 percent. Beans that initially have a low moisture content of say, less than 10 percent, have less free moisture level and will tend to roast much faster and, conversely. beans with a high moisture content (fresh crop beans often have a moisture content in excess of 14 percent) will roast more slowly (or need more heat). Moisture and density are not the only factors but they certainly are very influential on roast speed and can vary from region to region and batch to batch.
As for bean density, I read an interesting article recently (in Roast Magazine, I believe) by Willem Boot that touches on this subject and advises the following (I haven't confirmed this personally):
For hard beans, roast with a relatively high initial heat and moderate heat in the final stage of the roast process. Examples: Kenya AA, Guatemala SHB and almost any coffee grown higher than 5,000 feet.
For medium hard bean types, roast these with moderate initial heat and moderate heat in the final stage. Examples: Brazil, Sumatra, Java and most Latin American coffees grown lower then 5,000 feet.
For soft bean types, roast these with low to moderate heat during the entire process. Example: Hawaiian coffees, Caribbean types and beans grown lower than 3,500 feet.
Again, I haven't approached my personal roasting with this much analytic thought, but I will do some looking back at my roasting logs and see if the roast profiles I've developed for myself reflect this advice.
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.
= No New Posts since last visit 