HomeRoast Digest

Topic: The Effects of Light on Coffee (6 msgs / 113 lines)
1) From: Eddie Dove
What is the effect of light on green coffee beans and why / how?
What is the effect of light on roasted coffee beans and why / how?
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2) From: Kevin
From what I've noticed, light has similar effects on green and roasted
coffee.  Light tends to make green and roasted beans more visible to
the naked eye.  :->
There was a post a while back discussing the effects of UV light and
how over time UV light could degrade the volatile compounds in coffee
and reduce flavor.
My home coffee roasting blog:http://homecoffeeroastblog.blogspot.com/Kevin

3) From: Ken Mary
I cannot comment on green coffee.
Some of my resting experiments years ago involved putting roasted beans in a
shallow dish on a north facing windowsill. The coffee went through its
normal rest behavior over 4 or 5 days until it was consumed. The coffee
suffered no ill effects from this exposure. In fact it was better in all
respects than the partly sealed controls. There was no difference between
coffee exposed to light and coffee stored away from light in open
containers. This convinced me that all of this vac sealing and storing away
from light is unnecessary. I have never been disappointed with coffee stored
in open containers over a week or so until it was consumed. With closed
storage, I got definite foul tastes, and the expected improvement with
resting did not occur.
There may be exceptions such as dark roasts with surface oil. And you
supertasters may find some effects that I cannot sense.
I do not demand that you do what I do. I am just presenting the facts as I
see them. For over 7 years I have stored coffee in open containers and have
never had any adverse flavor effects. Although for convenience it is stored
in a kitchen cupboard in amber plastic containers.
Sorry about the rant, but the newbies may get the wrong impression that
closed storage is the only "correct" way. Do your own tests.
Kevin has stated that UV may damage coffee. Little or no UV passes through
window glass.

4) From: Brian Kamnetz
Again, darned interesting. I keep roasted coffee in sealed jars. I consume
it between 2 and 11 days after roasting, and I have noticed an odor that
suggests staling toward the end. Based on your results, I think I will take
the covers off...
On 1/17/07, Ken Mary  wrote:

5) From: Rudy Ramsey
improvement with resting did not occur.
Have you done any experiments, or do you have an opinion, about how this
would be affected by using bags with one-way valves, rather than completely
closed jars? I'm wondering if allow the CO2 to escape solves the problem or

6) From: Ken Mary
My tests were done with jars that did not seal airtight, so some CO2 likely
escaped. When opening the jars there was no puff of gas. Others have claimed
that their best results came with valve bags, but I have no experience with

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