Rocks in green beans

soloespresso

Okay, I have to admit I wake up in cold sweat at night thinking about rocks getting caught in my grinder burrs. I have voted for paranoid. I usually pour my 70g batch onto a plate and examine each bean carefully, although lately my standards have dropped.

Are there any beans that I should watch out for, are there any beans that are safer, what precautions do people take to preserve their burrs?

p/s rock + ceramic burrs, just thinking about this is going to give me insomnia.

Kelsey

I'd worry more if I hadn't seen what happens when something too hard for the SG gets in the burrs - it stops grinding, tho the motor valiantly tries to keep going. You can hear it tho, so unless you walk away when grinding, you should be able to stop it pretty fast. Ceramic tho. Don't know how I'd feel about that.

Lacehim

I've never found a rock yet!  Lets hope it stays that way!

Brett H

I had a small rock in the Rocky. It crunched it before I could hit the off switch. Upon inspection with the lapidary visor there was no damage to the burrs so I must have gotten a very porous rock as opposed to something further up the MOHs harness scale. I am really careful about checking the greens before I roast!

RichardM

I haven't found a rock yet after an estimated 80kg. I do run the beans through my fingers as i pour into the roast cage, then back into the cooling bowl.  I check some of the more exotic ones a bit more carefully. TBH if a rock killed my blades in the SJ, I'd just get new ones. They are a consumable. Would just give me a reason to do them early.

soloespresso

on 1319541844:

I check some of the more exotic ones a bit more carefully.

Which ones are 'more exotic'? I know Ethiopians are notorious, but anything else?

RichardM

Other than Ethiopians, generally ones from smaller estates in countries that aren't necessarily big producers - Laos would be another one that don't seem to be as well sorted.

Muscles

To be honest I have never given it much thought. I did actively search for debri with the free Harrar from MyCuppa but only because Jeff recommended we do so.

Bottom Line

Found them a few times. A couple in Yemen and quite a few in the Harrar from Jeff. The Harrar was at the bottom of the bag so to be expected and Jeff mention that they would most likely be there. Never in a wet processed bean. Guess there always is a first!

greenman

The most stones I have encounered was in a couple of batches of Yemen Bani Ismail, I had enough stones to start a quarry :D :D

mycuppa

Debris, mostly rocks or stones, can appear in coffee for all processing types but there is a higher probability for dry processed. You would think wet-processed/washed coffees would be less likely, but never assume anything. I've processed 3 pallets of PNG (from the same farm/lot) in the last 2 months and one of the pallets had some bags so bad I was yielding 2-3kg rocks per 60kg green bag - they were particularly nasty, heavy, hard rocks identical in shape, colour and size to a roasted bean. Some bags from the same pallet even have rocks and others not. There is a myth that buying expensive, high quality green beans gives you immunity from stones - nope, but it is true that lower grade beans increase you chances of picking up unwanted stuff. More dangerous than rocks are small, hard pieces of wood that are shaped like beans and are nice and light - so easy to lift on the destoner and get carried into the good stuff. These babies can stall a small grinder very easily. It can be true some regions are more prone to debris than others. Some farms are also less careful. One thing is very certain - the more coffee you play with, the more stones will cross your path.

Koffee_Kosmo

I tend to inspect the beans prior to roasting I suppose its easier to do this at home with small amounts as opposed to commercial roasters Anyway back on subject I have the pleasure to find - wood, glass, nails, and rocks The pleasure is in the fact that the foreign matter was discovered  ;D I dont get to concerned about as its rare, but I have a vigilance routine KK

beanflying

Like a few of the others YEMEN and some Ethiopians. Generally I pre sift these with the seive shown below. Its a 4mm grading one I picked up of evil bay for under $30 delivered. Most of what I have found is sand grit and other small dried junk which this happily lets through. Quick visual sort after this pre and post roast and I am yet to find anything you would call a rock that would damage metal grinder burrs. Photos of nails, bolts and other chunky stuff are around on the net too so it's worth looking at all beans as you roast them.  ??? There is a little Hazchem thread around here somewhere with issues with a Vario and a rock and ceramics certainly won't like impacts where metal burrs will chomp the small sandy or even concrete ones and keep going.

Koffee_Kosmo

I have a similar grading system These gold prospecting sifts were given to me by my father in-law 2 sises of wire mesh and they also stack KK

UNM

I don't worry about stones. Never seen one in any of my roasts, including the harrar from Jeff. I visually check before roasting, then again  while pouring beans into roaster, if I saw anything, I'd check carefully before bagging up. When grinding, I grab a handful from the bag and tip it into the grinder - would pick any stones out if I saw them at this stage too. I reckon with those basic precautions, risk is reduced and cost of new burrs is approx $50 - at that price, I am not going to waste my valuable time in any additional  sifting or checking. Also, my bean usage is somewhat less than the likes of Jeff, or many others on this forum. Edit: And as for bits of wood, I doubt they'd stall my grinder. 550W should take care of them quite effectively

Dry_bean.

Over the past 12 or 18 months I have probably found 3 or 4 stones in green beans, as others have commented mainly in beans from Yemen and Ethiopia. A couple of weeks back I found a corn kernel in a batch I was roasting. FWIW the stones I have found are quite crumbly and light, nothing to damage your grinder here, although a few weeks back I found a piece of granite "approx 1.5 times the size of a bean" in a batch of Yirg, that would certainly have made the sparks fly.

mycuppa

on 1319611157:

Over the past 12 or 18 months I have probably found 3 or 4 stones in green beans, as others have commented mainly in beans from Yemen and Ethiopia. A couple of weeks back I found a corn kernel in a batch I was roasting. FWIW the stones I have found are quite crumbly and light, nothing to damage your grinder here, although a few weeks back I found a piece of granite "approx 1.5 times the size of a bean" in a batch of Yirg, that would certainly have made the sparks fly.

Corn is quite common as I'm sure they must reuse the jute bags despite them looking new. Most green bean bags are new, but some origins such as Ethiopia have trouble sourcing the hessian/jute, etc. and sometimes recycle them. I often find a nice piece of white/yellow popcorn floating at the top of the cooling tray when the beans exit the drum. Sort of looks quite nice contrasting against the brown beans - coffee-infused popcorn. I grab it quick and put the tasty morsel in my gob !

mycuppa

Some of the more interesting things...... Half a silver watch band, Ring. Ear-ring. 7 inch nail - that was very noisy banging around in the roaster during the roast cycle needles screws, nuts and bolts metal bracket necklace (beads) cotton scarf part of a straw hat There are 2 stories I've heard....... 1. A roaster in Brisbane during 2008 was roasting and midway could hear some loud bangs. Apparently, the Colombian Supremo he was roasting from the now defunct ARC had bullets in it. Apparently, he called ARC and asked what to do whilst the roaster was still running. 2. A roaster in Melbourne found a full length finger in his bag of beans, evidently sheared at the primary knuckle. Ah.....the stories.....

soloespresso

on 1319614708:

2. A roaster in Melbourne found a full length finger in his bag of beans, evidently sheared at the primary knuckle.

  :o

Brett H

on 1319614708:

2. A roaster in Melbourne found a full length finger in his bag of beans, evidently sheared at the primary

1.  I hope this was pointed this out before he roasted it 2. Did the Roaster change his signage to read: new digital roaster now on sight 3. Fingers were pointed but the supplier denied all responsibility 4. Did his assistant give him a hand removing it 5.

shape_shifter

So far besides Jeffs Harrar (which obviously we all knew about) the only other bean has been the Ghimbi, only one so far and I found that after I had roasted the beans when I was cooling them before I used the popper to cool. I think I probably have a better chance than others seeing as I only roast such small amounts at a time. No idea what will happen when I upgrade, well either that or I just keep buying Jeffs blends  ;D

BLrdFX

on 1319541801:

I had a small rock in the Rocky. It crunched it before I could hit the off switch. Upon inspection with the lapidary visor there was no damage to the burrs so I must have gotten a very porous rock as opposed to something further up the MOHs harness scale. I am really careful about checking the greens before I roast!

I had a rock get into my Rocky too!  All the years I have been grinding beans it was a first, and it really shocked me and worries me now.  I do not roast, YET, but when I do vigilance will be the word to follow.  Also, single dosing makes vigilance much more practical :-)  Spotting a roasted rock, or worse (a finger?!!?! #%*@#) would be a much easier task.

Kelsey

I'm more cautious with some greens than others, but they all get a visual inspection. Sumatran Kuda Mas has always held some interesting surprises for me - including a chunk of concrete the size of about four beans!