A frustrating to long dry, to short yellowing

Hi guys, im pretty new to roasting and trying my best to achive some sort of light fruity roast… and rn getting the feeling of banging my head against the wall over and over again. Color is fine when done, but very little fruityness.

Im having trouble keeping the dry less than 50% and when I push the temps I create to much momentum into yellowing and it speeds through it. Can someone that actually knows what they’re doing (obv unlike me :sweat_smile:) please shine some light on this?

Bean → Don Senel Micromill Obata Honey - Ally Coffee


Just my 2 cents as I noticed you roast a small 250g batch - when I started roasting on the Bullet 2 yrs ago I was roasting 300-350g batches. That said, I noticed you marked Yellow at 357F on that roast above (I went to RoastWorld to find the roast above) - which is higher than when I mark my end of Yellow phase. I mark around 333-335F - that usually gives me a yellow/drying phase of between 40-45% depending on bean and total roast time (and batch size). I also start at a lower PH than you for small batch sizes, either 392, 401 or 410F and let it do about 1 min (to turning point) of heat soaking at P6 or P7 before bumping to P8. These days I roast a full 1kg batch. I have found batches between 1lb up to 1 kg are easier to work with than the small 300g batches. The small batches will run faster esp with higher PH.

Since you also said you wanted a lighter roast, I would definitely start with lowering your PH temp first before anything else. Not sure if @bradm is around, but he has it down with roasting to get the fruit to shine - he might have some advice for you (I learned a lot from him). These days I tend to roast to almost SC as I’m going for that more chocolate profile (because my friends want medium dark since they add milk or make espresso drinks).

Happy Roasting


Thx for your reply and input. Regarding marking time of yellowing I’m not really marking it with temp in mind. I’m marking it when I cannot see green in the beans anymore. Right or not?

Reason for high PH is me trying to get to yellowing faster but without scorching the beans. Trying to find some sort of sweet spot for dry phase with higher temps. But all that did was generate to much momentum when coming in ti browning.

Appreciate your response a lot. Struggling here :joy:

I agree with this. It has been my experience that when you are micro batch roasting, the beans are changing faster than the thermal probes are telling us, leaving us to try to catch the horse after it has left the barn. I have settled on 800g for my roast size, because that is what fits in my glass jars after roasting.

I typically mark yellow from temperature after watching many roasts and smelling the beans in the trier and I normally mark yellow at 335-345. I don’t trust the color through the window. The LED light makes everything look much greener than regular incandescent.


FWIW: I roasted a lot of 325g batches, selected to get 7 roasts out of a 5# bag of beans. I settled on PH temps of 195C for darker roasts, and 210C for lighter roasts, especially Ethiopians. If you look at some of my profiles, the best ones have “Great” or “Excellent” in the names. To follow them precisely you’ll need to preheat for exactly 15 minutes.

I also moved up to 450-500g batches, and more recently to 800g. I agree they’re easier to control, and the beans seem somehow more well developed.

Hope this helps!

  • Brad

It’s right but as Bill said also, looking at it thru that little window with that USB light can be deceiving. I chose 333-335 (although some beans that are darker in green state I’ve marked around 340F) because on average that’s around when the beans is a soft yellow when using the trier.

But I definitely encourage you to take a look at Brad’s profiles for his small batches - he’s the man if you’re looking for fruit in your cup. :slight_smile:

Happy Roasting.

1 Like

There 2 things I noticed. First, the Yellow Point is around 180 degrees, normally it shouldn’t be around that high temp, I guess the raw beans are more into yellow than green, which may cause a trouble to determine the true yellow point. If that was the case, maybe holding raw beans while you check the trier will help you do to the comparison.

Second issue is about IBTS and Bean temps graphs, they are very apart from each other, that makes me think you did’ preheat the Bullet enough. For 150 degrees charge, maybe 230 preheat temp will be enough, after 20+ minutes, there is a charge pop-up dialog box will appear, thats mean your roaster is fully charged with energy. You can wait until you reach 150 degrees, then charge your beans.

Note : if the charge pop-up dialog box appeared to you, no need to press the PRS, just charge the beans inside the roaster, the bullet will start the roasting process instantly.


Re: perceived bean color, I use an inexpensive, clip-on, adjustable color LED lights as recommended by @wm1:

Looks like this particular light is no longer available but similar ones are. This is a big improvement in color compared to the light that came with my Bullet a few years ago.

Sorry to digress a bit…


Just to update for others that are viewing and might be doing the same stupid mistake.

I’ve been preheating and not waiting for the bullet to say charge. I’ve been watching the drum temp and when it hits my desired temperature I’ve manually charged it.

Preheating time before: like 7-8 min?
Preheating until it says charge and the ROR has stabilized: 16-25 min (depending on my office room temp I guess, it varies (fixing that)).

That changed it all!

Thx for valuable input, and if I had read the manual I would’ve gotten a hint or two about this :rofl:


Hoping the data we supply to aillio will eventually be given back to the community in some form of general data. Like what is the average reported “yellow” phase temp.

I think if we knew we were getting this info back in automated reports, we’d all be more diligent in utilizing the proper data box inputs on roasts. I currently am considering moving to cropster. far better for getting analytical about your own roasting, and the cropster community is really informative.

Good to make sure you have a high CRI LED light that is bi-color and variable in temp. Every room and lighting combo is different and you’ want to dial in the light to get the best ability to see color changes accuratel in the beans. the supplied LED stick that aillio provides has a green spike in the color spectrum and it makes the bean appear more green. If you get a good quality LED light, made for cinema use, or possibly those GE “reveal” series lights, you might be in a better way. Don’t typically want to go too warm in lighting, as that can make things appear more mono colored, and you lose some ability to differentiate nuances. Then once you lock in a good qulity of lighting, stick with it until you can figure out the average tempuratures for specific color changes. LIke when do you begin to see the start of the change from green to yellow? and from there when is the whole batch yellow? That will be a fairly big difference, and everyone may call it differently. Calling “yellow” is really subjective, but calling “green to yellow” is more specific and repeatable. Then you have to factor in altitude. These color changes seem to be effected by altitude, since the color change is tied to water evaporation.

Being able to auto populated altitude or enter barometric pressure of the day would be great data points in Roastime 4.

Roasting 1lbs (roughly 453 grams) or less, there is plenty of power in the P settings to go from slow drying and fast browning. and the fans allow for the opposite. Fast drying and slow browning. It is a dynamic little heater box. Only seems to lack in absolute heat transfer. I think that the airflow is cooler than gas roasters, and that there is less IR heat transfer. total speculation though. Just that is how it feels when roasting in cooler weather.


Glad to know everything is going well with you, happy roasts and happy new year in advance.


Thanks for the information about CRI. I was unaware. I have ordered an LED light with 90 CRI.

1 Like

Which one did you end up getting?

i ordered this one:

This lamp has to be turned on each time you plug it in. It does not “remember” it’s on and off setting. it does “remember” which color range you had set the last time it was on.

It really does help with the color.

I am still looking for one that is more in the same form factor as the original. I would prefer less cable to tidy up.

Thanks Bill! Added to my “list” :laughing:

I went a little overkill and bought a Quazar Science Bi color tube. They have some of the most accurate LED color in the world at this time.

Other companies are doing good things, as well.

having a nice even spread can help too. hard shadows can hide defects and make the beans appear more visually busy. A 2 foot quasar tube can push light to either side of beans and you end up seeing more of the bean color instead of shadows.

i’d assume many of the home LED bulbs are getting better these days, so anything with good CRI or TLCI ratings tends to help a lot.

But we do so much based on the color of beans, a cheap LED can give your horrible visual feedback.

The traditional tungsten/incandescent lights were naturally color accurate, because it is heat generated, so it has a full spectrum color band, but is decidedly skewed warm. So it has less ultra violet, a little more blue, a little more green, and more yellow, and then a bunch of orange and red in a progressive almost linear increase. So it has a very even look despite being warm. This issue is that warm does skew the perception of how “yellow” a bean is. Today we have LED which is all made from dyes and pigments. So it might have an uneven color spectrum, which can appear “cool and white” but have serious dips in one of the color groups in the spectrum. And the warm LED can be almost montone in color having almost no blue spectrum.

Flourescent and LED both often have a green spike in their color spectrum. that is why old flourescent tubes often fave off they ugly green cast. LED does this more subtly, and is less a result of nature, and more because the manufacturer gets the color dye ratios wrong, or has issues making some of the colors more even.

We could just roast bu nose, but the nose gets fatigue pretty quickly, so i feel being able to trust your eyes is crucial too. In the past we never had to worry about the color accuracy of old filament bulbs because they were inherently color accurate. LED lights are a new industry challenge, but super crucial. In particular as influencers like Rob Hoos talk about how color is a major factor in flavor. So anything that throws the eye off is just throwing you even further off.

If you want to play around with visuals, you could also get an RGB tube or bulb from Philips Hue or Aputure, they tend to be accurate overall, but it allows you to play around with extreme colors via a phone app. You can check your beans under pure red, purple, blue, green etc. It tends to be a great visual tool. Good for inspection fun. But at the end of the day, having something repeatable and consistent by the roaster will be most important. So I might not have an RGB light there for fear i lose consistency by accidentally changing a setting on the light. I do however like having something bi-color to sort of adapt to the light coming in from outside. I find our eyes adapt to ambient conditions of light, so i like being able to slightly match the room a little warmer or cooler. but not having the option to skew green or magenta, or effecting saturation or all those crazy options. Just having a simple way to consistently and accurately dial warm or cool based on the time of day or weather outside.

Hope this helps!

Wow, Great write up.

Are you checking the color through the window?
Or in the trier outside of the Bullet?
Or both?

I agree about roasting by nose. Some days my nose can smell everything, some days my nose doesn’t smell anything. Taste buds too.

1 Like

I roast by looking through the sight glass (window), and minimally use the trier. Just way too small of a machine, and the temp variation has a bigger influence on flavor and heat momentum. in the summer i might use the trier more. Edit: also, i can often smell the roasted aromas through the natural exhaust since the roaster isn’t air tight, and the whole thing is fairly small. the trier i use for when i need an intense smell, or a very specific time/temp smell signature.

Our nose is not so good in the mornings, so it can help to do some exercise before roasting. Sleeping in a dusty room, or sweeping a dusty garage can impair your olfactory nerves for a couple days. Soldering, grinding metal, or welding has huge impacts on the nose. Wearing certain perfumes. Cutting wood. Using certain bathroom cleaners that might aerosol or dust powder and get inhaled more. Eating too much refined sugar in your diet can effect many of your body’s functions, which go unnoticed until you want more performance out of them. So even without allergies, a lot can happen to impair smell on any given day.

Our sense of smell (and therefore taste) tends to improve throughout the day. Cupping in the afternoon in theory yields better ability to discern and taste, but then you get a caffeine hit later in the day. haha. so, i still do my primary cupping in the morning, but will do additional afternoon tests on smaller sample sets. or save bigger cupping sessions for when i can tolerate a bad nights sleep.

The issue with a smaller toasting machine is how much more cupping we end up needing to do. The amount of environmental influence on temps between roasts is insane. has flavor impacts. pulled the trier more times on this batch? different times? everything is so sensitive. just the nature of inertia and mass.

So i find myself getting more caffeinated with this little 1KG roaster than i do with a larger one because QC frequency is insane.