HELP! What’s happening to my beans?

There seems to be always a massive misconception between tipping, scorching, blowing, and burning.. The main problem is there’s no naming convention – does “roaster” make reference to the individual or the device; is “dropping” taking the beans out or putting them in to the drum? Is “tipping” and “scorching” a similar thing and how can we spot the difference?

Well, I don’t know who decides on the precise naming conventions, but here is my take on it:

Tipping
The term “tipping” most likely refers to the phenomenon where in actuality the “tip” of the bean burns black. That produces sense to me, at least.

How exactly to “spot” Tipping

Tipping happens when the beans experience any temperature too much for the bean’s heat-transfer coefficient. i.e., there’s so much energy (heat) around a certain part of the bean that the bean cannot absorb/conduct/disperse the power fast enough. The sole choice left would be to burn in that area.

An analogy can be found in any form of meat grilling. A straightforward lamb chop on the grill has tipping round the edges. That is caused by too much heat at any one time, evoking the meat to char in place of cook starting a coffee roastery. This really is what are the results to the beans: there’s too much heat for the bean to use up, therefore it burns.

What can cause Tipping?

So, when does tipping occur? The fact is that people don’t know exactly. This is above tells us so it sometimes happens at any time, whenever the temperature is too much throughout the roast. It sometimes happens due to too much a receiving temperature (the starting temp), too much a slam during roasting…too much heat anywhere!

The next question is whether that is caused by convection or conduction heat? Put simply: may be the drum too hot or may be the air too hot? The solution is: either. Tipping is a factor of the beans, not the environment, the roaster, the drum, or air temperature. The truth is that the coffee bean cannot handle it.

Go through the image below:

Tipping
Photo Source: www.sciencedirect.com

The colours show the difference in temperatures in the beans. It’s clear from the image that, if anything should burn, it will be the tips of the beans! But this changes depending on the bean: try finding tipping on peaberries. As the peaberries are round and has almost no distinct “tip”, the chances of tipping happening are much smaller in peaberries.

What is the effect of Tipping for you roast?

So, is tipping a poor thing? That’s a concern only the drinker can answer. Allow me, as I cannot stress this enough:

TASTE YOUR COFFEE!

Put simply, if the coffee tastes bad, then tipping is bad. If your coffee tastes good but you have tipping, then surely tipping is not just a bad thing! May be the “tipping” on the lamb chops a poor thing? No, most of us love a little char-grilling on our chops. But surely that is per definition a burnt chop? Well, possibly so, but it still tastes great!  The chances of tipping affecting your roast to the level of experiencing to dump it all is quite slim.  Chances are that the chosen profile or roast degree is way off, and that tipping is just a really small part of the problem.

Scorching
So, if tipping is a burnt spot on the tip of a bean, then what is scorching? If you ask me, scorching is bad practice. Certainly not a poor tasting bad practice, but the one that points to inexperience on the side of the roast master.

Scorching happens when the bean touches an area that’s too hot for the thermal conductivity of the bean. The same as for tipping, but almost exclusively caused by conduction heat. In layman’s terms: your drum was too hot! Here is another cooler charge temperature or reduce the ramp-time of your profile to negate any scorching. You should not need to scorch the beans to reach your chosen roasting profile.

Scorching is different from tipping in so it typically presents on the flat side of the bean. It is a larger spot that’s burnt black.

This is what scorching seems like:

Scorching
Photo Source: www.perfectdailygrind.com

Cratering
There is of confusion between craters and tipping. Both are VERY far apart. Cratering happens near or into second crack where in actuality the pressure in the beans is released at such a higher level that the bean’s surface cannot handle the release. That is per definition “second crack”, but in case of cratering, the 2nd crack was induced so much so it affects the structural integrity of the bean and literally blows a piece off when the bean releases the built-up gasses in the bean.

Crating
Photo Source: www.fullcoffeeroast.com

What is the solution?
If you select that tipping, scorching, or cratering is the explanation for any unwanted flavours in your bean, here’s what to do:

Tipping: Reduce your charge temp and do a slower, gentler roast.  Increasing your convection heat should also help, in addition to increasing the batch size and drum speed.  The best is always to roast longer and gentler to permit your beans enough time to absorb and distribute the power that you want to force into them.

Scorching: Reduce your charge temp and raise your drum speed.  The less time the bean spends on the side of the drum, the less scorching you’ll have. Try to maximise your convection heat and minimize your conduction heat, i.e., transfer your energy in the shape of hot air in place of a warm drum.

Cratering: Increase the full time from first to second crack and take a gentler approach will help to prevent cratering.  Dial back on your gas pressure once you reach first crack and let the beans carry themselves into second crack.   In the event that you force more and more energy in to the batch, it stands to reason that “something’s gotta give&rdquo ;.In this instance, the entire bean is splintering apart because of your importance of burnt coffee!

The Genio Academy, as well as Shaun Aupiais from We Roast Coffee produced a brand-new online Coffee Roasting 101 course on our Genio Hub, available to any or all Genio customers, where he discusses common roasting defects in depth. Click the link to see this type of module.

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