To roasters: do you ever get a relatively moist batch of beans? What do you do with them?

I have a batch of beans which smell great. However, upon City-City + roasting, my moisture loss is up to 19%. I have no quantitative measurements, but my guts are more comfortable with only 13-15% losses at City+ level -- i.e., my perception of the fully-developed roast level.

According to a pro-roaster I chatted with, his standard for green beans must lose only up to 15% for a nice, city/medium roast, so I guess there's some agreement there.

Some questions:

1. Do coffee companies strictly agree with the producer on a moisture level pre-shipment and expect this to be the same post-freight?
2. Do coffee companies apply non-roast drying methods post-freight if some greens are too moist?
3. Is moisture level a non-issue and should just be compensated with roast profile adjustment and costing adjustment? (I mean, for big importers, do you REALLY have the time to check moisture levels and dry them out over your roof or something..? There sacks and sacks of coffee!)

wearashirt wrote:...
According to a pro-roaster I chatted with, his standard for green beans must lose only up to 15% for a nice, city/medium roast, so I guess there's some agreement there.

Disagree with your gent.15% is not an absolute.

1. Do coffee companies strictly agree with the producer on a moisture level pre-shipment and expect this to be the same post-freight?

It should be around 11% maximum. Higher moisture levels will mold. I will ask Joe Marrocco if some contractual agreement is made beyond basic weight, cupping score consistent with pre-shipment score, and mold-free condition. I believe 1.5% is the industry standard for +/- factor on weight. I could be wrong.

2. Do coffee companies apply non-roast drying methods post-freight if some greens are too moist?

No. If it is too wet, like any ag product, it will rot.

3. Is moisture level a non-issue and should just be compensated with roast profile adjustment and costing adjustment? (I mean, for big importers, do you REALLY have the time to check moisture levels and dry them out over your roof or something..? There sacks and sacks of coffee!)

Non-issue? It is a data point but you roast for cup quality, regardless of 12 or 14% moisture loss .More than water accounts for weight loss. Our importer uses a moisture meter when shipment arrives. If the coffee doesn't sell out, it is measured, roasted, and cupped periodically to ensure that quality is holding. If it "hangs around" too long (drying out is one factor), it is sold off inexpensively to roasters who use flavors on their coffee.

Boldjava wrote:Our importer uses a moisture meter

And, you too can measure the moisture content of your greens with this Wile gizmo.
http://my-tonino.com/shop/en/wile/

I haven't been rigorous in analyzing the difference that various moisture levels make on my roasts, but I am at least recording the data on each bean and will try eventually to put it together in a way that helps in my assessment of what works and what doesn't.

These Roast Magazine articles answer the OP's questions and provide lots of background:
http://www.roastmagazine.com/resources/ ... tWater.pdf
http://www.roastmagazine.com/resources/ ... Nature.pdf
They are the basis of a talk given by Cafe Imports at NRF year before last.
Water activity (unbound water) is more important than total water content in ag products inc coffee.
Don't spend hundreds - you can measure water activity with a $2 RH digital meter from fleabay. They are +-5% accurate but just calibrate them as they are quite repeatable.
Cafe Imports have been recording cupping score vs water activity for many thousands of samples and there is a flatish peak at around .57 aw (57% ERH). Anyone have an update on their data?
To answer the topic - I put my incoming greens into permeable bags (calico) and stack in constant humidity chamber at 56% and beans come into line within a week or so. Removes one source of variability in the roast. I am still experimenting and only been doing this for six months.
Eric

Thanks everyone for your insights and references! Gonna read up on them first.

This is important to me because I source locally, so no part of my supply chain is so professional as to get measurements, get averages... I'm only glad that my broker uses a digital scale.

I read this paper a year ago, and it has made me believe that initial moisture content has an effect on the roasted coffee. However, it doesn't conclude whether extra-dry coffee is "better" since it just analyzed aroma compounds.

COFFEE ROASTING AND QUENCHING TECHNOLOGY - FORMATION AND STABILITY OF AROMA COMPOUNDS. Jürg Baggenstoss (2008)

wearashirt wrote:It has made me believe that initial moisture content has an effect on the roasted coffee.

Yes, it does have an effect. I sometimes pick coffee (wild) and prepare my coffee greens. I don't have a tool to measure humidity, so I just check how hard they are: hard = dry. Not very accurate.
Beans that are more humid don't roast in the same way: when they reach second crack, they are already oily, which never happens with beans that are dryer.
The taste is different, but not bad.

alki wrote: Beans that are more humid don't roast in the same way: when they reach second crack, they are already oily, which never happens with beans that are dryer.
The taste is different, but not bad.

This is an interesting insight. Can you describe more in terms of cup characteristics?