Coffee Roasting Pro-Tip #15: How to deal with the Dip

[@psychadeliq]

Scott Rao's Three Commandments never said gas should always be declining. It was the ROR part that should always be declining. Somewhere around his website, he mentioned that he never touched the gas setting 45s before and after FC. I think this is key. If you keep you gas constant during that time window, it would also delay/reduce the dip. I managed to get constantly declining ROR this way.

[@CompoundCoffeeCo]

Yes, it isn't part of the three commandments. However he did mention that the gas should never increase at any part of the roast. You can check out our Instagram TV version of this video, Scott himself commented on it. The only exception for him is the "Gas Dip" method which he believes to prevent the "dip" issue.

[@stevebrown6049]

I believe in chp 10 of his book he does give a "best practice" where gas is decreasing from 295 degrees on up. He does talk about this same concept though in 11 about controlling the DIP

[@danmohan1981]

I think you all are misunderstanding RoR. Its the RATE that is decreasing, not the temperature. If the RoR is positive (even if it is declining) the temperature is still increasing, just not as fast. After the flick, the temperature has just increased from the super heated steam inside the beans getting released (first crack). As that burst of energy dissipates, the rate that the bean temperature increases will be a little less, because the steam is no longer under pressure and quickly drops to 212°F. The BT continues to rise from the energy coming in from the burner, but not quite as fast. The flick might even be from a false reading of bean temperature as the steam release hits the probe, but the actual beans don't experience the flick.

[@reidjam7]

Thank you. I appreciate your clarity and delivery. The explanation of principles is clear. I'm roasting on a micro-roaster, a Huky 500, set up very carefully with good control of air and gas as well as chaff collection. My experience is at variance with your suggested remedy for the dip after first crack: namely, as verified many times in my experience, applying gas to mitigate the dip invariably results in a vigorous flick as development ratio approaches 20%. Instead, I use a modification of Rao's recommended management of the latter part of the roast. At first crack, depending on the profile, I might, for instance, be at 1.1 kPa flow to the burner. At 2% development ratio, I'm going to drop my gas flow by 20% and repeat that every 2% increase in developmnet ratio until finally cutting the gas completely at 8% or 10% (my stove flickers when the kPa is below 0.3, so I have to just accept whether or not it's going to stay lit. 🙄 With the Huky, this generally produces a gently and constantly decending RoR. Lately I also decrease the air flow after first crack which seems to support a more gradual diminution of RoR. Another tool that I find helpful on a practical level is to put a previous roast curve of the same or a similar coffee (origin, density as suggested by MASL) in the background with Artisan. Then I can foresee particularly tricky areas of the curve and, hopefully navigate the roast a bit better. "A little learning is a dangerous thing; drink deep, or taste not the Pierian spring." --- Alexander Pope Cheers all, -- james

[@hoseinmohamadzadeh4212]

Increasing the gas certainly solves the dip but there is a high chance of smoky flavor.

[@Skinnyriver]

There is so much confusion regarding these theories. Can I ask 2 questions: 1) how does increasing the heat help avoid the ‘flick of death’ as you stated 2) some say the release of steam is the exothermic flick event, you state it is the dip event? If it’s the dip what is happening during the exothermic flick

[@CompoundCoffeeCo]

1) It doesn't help to avoid it. It only helps to minimize the severity of the dip. 2) The release of steam causes the rapid dip in temperature readings recorded by the probe. Once the steam has been sufficiently expelled, heat transfer becomes more efficient and that causes the ROR to rise again, causing the "flick"

[@Skinnyriver]

@@CompoundCoffeeCo it still doesn’t make sense.. it’s flick then crash not crash then flick. Almost all profiles I have reviewed shows the exothermic event (flick) during first crack.. this goes against your theory

[@CompoundCoffeeCo]

@@Skinnyriver I think we are referring to different points of the roast when we refer to "flick". I am referring to the increase in ROR after the crash, not before the crash. The increase/flatlining of the ROR before the crash happens before First Crack (where steam gets released). It is not caused by the steam release.

[@wuhc55]

@@Skinnyriver do a google search but there is an article talking about this phenomenon which is actually separated into...rise, crash, flick. The flick occurs at the end because so much of the moisture has been expelled and the dry bean suddenly heats up too quickly.

[@maxlee6676]

@@Skinnyriver when I see a flick before a crash or dip it just looks like the beans are signalling that the expansion event is about to occur because if you think about the inside of the bean just before the expansion, the core must be super hot and pressurized right, so maybe the surfaces of the beans radiate heat into the environment signifying that there is enough heat and pressure building up inside the cores that the even more dynamic event (cooling/expansion) is imminent?

[@stefanociamarra2505]

Not true about Scott Rao. He suggests to lower the energy input right before during and passed FC start to avoid the flick. He definitely recommends to increase the energy input before the start and in the middle of the stronger FC stage, to be lowered then right before this stage is over (around 12% DTR as a general guideline). Therefore the ROR should be slowly declining and never flick or dip, not the gas or enegy input in the FC stages.