Saturday, March 10, 2007

defecting, part two


inspired by actual events, your humble blogger has decided to sort a random pound of coffee for defects, roast the defectless batch against a regular, other batch and cup the results. defects were culled using the scaa's defects poster as a guide.

so far the defect picking has been completed and here are the results. there were 72 defects in all, with the most common (38) defect being partial sours. the second most populous group were chipped, broken or partial beans (17), followed by peaberries (10). the rest comprised an amalgamation of the other cat 2 defects such as partial insect bites (1) and (very) partial black bean (2). the rest were unclear as to which category they neatly fit into, as their defectiveness was minor at best and displayed the markings of at least two defects on the list.

in all, there were no death knell defects to be found in the sample pound and this made me quite pleased. not that i expected to see any from this source whatsoever. only that it confirmed the presence of good beans. using the system for adding the defects, however, gave me a total of 12 full defects, which is 4 more than should be seen for premium grade and seven more than for specialty grade.

if i can get this camera in line with the macro lens i'll try for some up closes of the defects.
i'll also mention that in this randomly sampled pound i did not count beans with silverskin on them, something the scca poster indicates as a sign of immature or unripe beans. i didn't count these as defects because i have a pretty good foundation for believing that this source of beans is not picking immature or unripe beans, and because i rarely have any quakers in my batches of this coffee. i'm not sure what causes the silverskin to stay on--a sign of fermenting/drying practices that need to be tightened? i would venture that it's not a dry mill issue, as the beans are already at their necessary moisture content by that point. and i would assume it's not a pulping issue, as a pulper wouldn't remove silverskin anyway, the beans still being in pergomino. the only solution that seems left is fermentation tank/drying.

i digress. next post should be about the comparison cupping. maybe some defect pics.

ah yes, one more thing. while not on the scaa poster, technically a peaberry is a defect. i counted those ten in my defect total.

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12 Comments:

At Sunday, 11 March, 2007, Anonymous SL28ave said...

Hey, Jason.

The tough silverskin is often a sign of unripeness. I've done a few silverskin separations and the beans with the most silverskin taste dull and greenish. The beans with the least silverskin, which often have a smooth waxy surface too, often taste over-ripe.

I sorted an award winning American coffee a few weeks ago. I removed 38% of its beans as defective! Obviously the cupping between the two was night and day. And those beans were from clean coffee country!

 
At Sunday, 11 March, 2007, Anonymous sl28ave said...

I meant Aaron, not Jason. A blog hopping afternoon!

And I meant American coffee as in Latin America.

Time for a nap? :)

 
At Sunday, 11 March, 2007, Blogger blanco said...

thanks for the silversking findings, peter. i'll do another one in the future (perhaps along with this one?) and publish as well. most of these sskins easily came off with fingernail pushing and covered maybe a third of the bean at most.

we'll see what comes up. after i put my results up maybe you'd be willing to show me your notes for comparison's sake? thanks.

 
At Sunday, 11 March, 2007, Anonymous SL28ave said...

Sure. My notes are very simple, though. The cleaned beans are sweeter, smoother and more pleasantly aromatic through and through.

 
At Sunday, 11 March, 2007, Anonymous Anonymous said...

Oh, and 1/3rd silverskin doesn't sound like much at all. In some cases there are just no problems or the silverskin is meaningless... looking forward to your results.

 
At Sunday, 11 March, 2007, Anonymous SL28ave said...

that was me again. :(

 
At Sunday, 11 March, 2007, Blogger blanco said...

that was the operating assumption (that the silverskins might be a non-issue) in the decision not to cull them as defects.

we'll see....

 
At Monday, 12 March, 2007, Blogger 4-Arts Zero Defect Coffees said...

Good work here!!

Actually, I did such comparisons 3 years ago and got the result, or conclusion, that those greens clothed completely in the silverskin were not even fully ripe cherries before they are processed. How? When gathered together and roasted, brewed, the cup was quite astringent and lacked the sweetness that we can get from the normal fruits, e.g. the green bananas.

So the silverskin does matter, but only when the beans are completely and tightly covered by it. If you can see the bean surface itself for even only 20%, it doesn't matter because it's the processing method that caused such condition.

That's from one of my personal experiments log. Hope to be of use. :)

 
At Monday, 12 March, 2007, Blogger blanco said...

how does the silverskin remove itself from the bean in roasting? does it just burn off or does it "pop" off with first pop? has anyone observed this firsthand?

 
At Tuesday, 13 March, 2007, Blogger 4-Arts Zero Defect Coffees said...

Blanco,
There are 2 phases. First, silverskin would leave the bean surface when the bean begins to swell, which corresponds to the bean temp of 150C. And second, when first crack starts, bean temp 192C, most silverskin drops off the bean surface, also because of the swelling thing, not burned off.

Simon Hsieh

 
At Thursday, 15 March, 2007, Blogger Jaime van Schyndel said...

Intersting input Simon. I have been continualy impressed by the try anything attitude you have.

Aaron, sorting enough individual defects to roast out takes a lot of effort...

Sorting out the defects roasted vs unsorted roasted, you will see cup sweeteness improve greatly. You can send me a bag of the sorted ones for an opinion if you want ;-)

 
At Saturday, 17 March, 2007, Blogger 4-Arts Zero Defect Coffees said...

Jaime,
To try anything possible for a better and better cup of coffee is what we always keep in mind. From the green sourcing, the roasting, to the brewing parameters, all are necessary to be included into the crucial elements of "good coffee." Ppl sometimes just take 1 or 2 out of the 3 to dare the definition of a good cup of coffee, which in my humble opinion is just a way of marketing, not a real concern about the liquid inside the cup or the demitasse.

We shall clear this out and make a difference.

 

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