Roasting Yield

[charmon]

Hey,

Just wondering what the yield from roasting green beans is weight-wise? From what I understand 2kg green beans should yield about 1.6kg of roasted beans, i.e. a 20% loss. Any advice greatly appreciated.

[CakeBoy]

You tend to lose a fraction less with gas vs electric, but yes, 20% is about right.

[ivdp]

20% is a bit rough . . .
What kind of beans, what is moisture level when starting?
This might influence roasting loss from 16 to 20%.
And these are also rough figures!

[charmon]

Hmm...I thought there would be a lot of variables at play alright. In my experience good coffee's all about the variables. Thanks for the advice guys!

[JulieJayne]

Another variable is the level of roast. Sounds obvious, but dark roasts loose more weight than light roasts.

[Beanie]

I see 20% quoted quite often; however, in my personal experience with the Hottop, my average was about 17%. The range was usually 14% to 19% with 16% & 18% occurring the most frequently. The 16-17% tend to be with 'just' as 2C started. 18% with a few seconds into 2C but never rolling. 19% is my darkest roast which is when rolling 2C begins. The lighter & least weight loss occurred with roasts which were after 1st crack but before 2C.

With regards to Ivo's comment, I didn't notice much difference which beans I had in there.. regardless of origin, bean size, or type of process. The only ones I can think of which was so different from the average was a blend of the Malabar Gold and the decaf beans. I can't recall exactly what the loss % was but I can look it up if you really really want me to

[bruceb]

Roasting=loss of moisture. Regardless of how you roast, loss of moisture is an exact measurement of how "dark" the beans have been roasted. If your roast to charcoal the product will be completely dry (ignoring the microscopic amounts of moisture that will immediately be picked up from the air duiring cooling). It should be apparent that there is no way to avoid weigh loss when roasting.

Storage of beans throughout the year will cause increases and decreases in their moisture content (if not hermetically sealed). Moisture content can be determined without roasting. You will need to accurately weigh an amount of beans, then dry them in the oven for a few hours at 125°C and reweigh. The loss of weight = the moisture content of the beans. Disclaimer: The dried beans will no longer be usable.

I store my beans in jute or paper bags in a cool room year round with humidity from 22% - 27% winter to summer. The moisture of the stored green beans is 10 -12%.

Edit: A couple more thoughts. I always weigh the beans immediately after roasting and note the weight or percentage in my roasting log. This value often tells more more about the degree of roast than the color of the beans.

The bean-specific moisture loss only plays a role when the beans just arrive, ie. from shipping and storage. If you store all of your beans in one room you will find that they all have about the same moisture content within a few days, and consequently the weight loss to a particular roast level will be about the same. In my experience coffee from India and Indonesia arrives with higher moisture levels than coffee from Ethiopia or South America. Again, however, once I store them a few days the moisture levels equalise.

Second edit: Corrected the values for bean moisture and room humidity.

[Neo]

For mini500 aka 800n, it is about 20% weight loss at full city.

[ivdp]

Hi Bruce

I hope your moisture content of between 22 and 27% is for your room and not the beans . .

[JulieJayne]

With the Gene, 300 grams in, roast to begining of 2c gives 255 grams out. That works out at about 15% loss.

[bruceb]

Hi Bruce

I hope your moisture content of between 22 and 27% is for your room and not the beans . .

Thanks Ivo. That was certainly a mistake. The moisture in the greens is between 10 and 12%.

[bluevalentine]

Programmable Hottie
approx 15% light roast - 19% dark, checked over 65 roasts