Development Time Analysis

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Sam
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Development Time Analysis

#170

Post by Sam » Sun 14 Jul, 2019 11:08 pm

Hi Chris,

I have read the Kaffelogic Roaster's Companion but don't really understand how Development Time Analysis works.

If I run the K-logic classic profile at L3.2 and listen for first crack and record that time, should I then stop the roast at 20-25% DTR or let it run till the end of the roast.

If I do stop the roast at 25% DTR, is the level stored in the k-logic classic profile or in the log for the roast. When I next roast the same bean will the level be pre-selected?

The Roaster's Companion suggests starting the roast at a much higher level than intend. Does this change the time to first crack compared to setting the level at the default for the k-logic classic profile.

Thanks,

Sam

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Re: Development Time Analysis

#171

Post by kaffelogic » Mon 15 Jul, 2019 3:43 pm

Hi Sam

There are two ways to use DTR:
  • To give you information about your roast - in this case set the level you want, record first crack when you hear it, wait for the roaster to end normally, and then have a look to see what the DTR is.
  • To let you stop the roast at your desired DTR - in this case set the level really high so you know the roaster won't stop of its own accord, record first crack when you hear it, wait for the desired DTR to show on the display, then stop the roast manually. When you do this the level is automatically set to the point on the profile where you stopped the roast i.e. you have taught the roaster where to stop and it will now repeat the roast without you needing to intervene.
When you change the level you are changing the point on the curve at which the roast will stop. The curve doesn't change, so the time taken to first crack will not vary, even though the level changes.

Sam
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Re: Development Time Analysis

#179

Post by Sam » Wed 17 Jul, 2019 6:43 am

Hi,

If I lock in the DTR at 25% for my roasts how do I change the roast level for the same bean?

Won't bracketing change the time the roast ends and thereby change the DTR for the same profile?

Should I be aiming to keep the DTR in the 20-25% range? Within a DTR of 20 to 25%, what range can I expect for the roast level before needing to change the profile?

Thanks in advance,

Sam

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Re: Development Time Analysis

#182

Post by kaffelogic » Wed 17 Jul, 2019 8:45 am

If you change the roast level this will change the DTR. Always.

Bracketing does change the DTR - it means you are sampling a range of DTR values to see which you like the most.

If you want to roast darker or lighter with the same DTR you need to change the profile and this might require some experimentation before you are happy with the results.

There is nothing magical about the DTR. Scott Rao's guidelines of between 20 and 25% are very well supported throughout the industry, but you are free to follow your taste buds. Altering the level will easily take you outside this range and you would do that if it gave you a result you were happy with. The amount of level change required to get you outside this range depends on the profile - it's all to do with the shape of the curve.

My personal strategy is to find a particular DTR that I like with a particular profile, e.g. Ninja at 19% DTR. When I roast a new variety of beans with that profile I will supervise the roast and stop it at my desired DTR. Then I will continue to roast those beans at that level with that profile (unless I want to experiment further!)

Sam
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Re: Development Time Analysis

#183

Post by Sam » Wed 17 Jul, 2019 12:12 pm

Excellent explanation of how to use DTR.

It's nice to have a DTR to aim for and then experiment from there.

Will give it a go on my next roast.

Thanks,

Sam

mr. bean
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Re: Development Time Analysis

#900

Post by mr. bean » Mon 30 Mar, 2020 1:24 pm

Hey guys,

Very helpful information here as I get started with my Kaffelogic : )

So far, using the classic profile with roast level of 3.1-3.3 on about 4 roasts the DTR has been at least 40% on all of them. I wait till I can hear 3 or so cracks in quick succession before logging 1st Crack, so I don't think I'm doing it too early... is this unusual for classic profile at these levels?
I've roasted Indo, Ethiopian, & Peruvian... so don't think it can be down to bean type either.
Thoughts?

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Re: Development Time Analysis

#901

Post by kaffelogic » Mon 30 Mar, 2020 2:16 pm

mr. bean wrote:
Mon 30 Mar, 2020 1:24 pm
Hey guys,

Very helpful information here as I get started with my Kaffelogic : )

So far, using the classic profile with roast level of 3.1-3.3 on about 4 roasts the DTR has been at least 40% on all of them. I wait till I can hear 3 or so cracks in quick succession before logging 1st Crack, so I don't think I'm doing it too early... is this unusual for classic profile at these levels?
I've roasted Indo, Ethiopian, & Peruvian... so don't think it can be down to bean type either.
Thoughts?
Yes, you are right. Default profile delivers around 20% DTR at around level 1.3. At the level you are roasting DTR will be around 40%. If you want to get into Scott Rao's recommended 20-25% DTR zone, you need to roast either much lighter on the default profile (fast and light) or try a profile that delays first crack until later in the roast, such as Firestarter or Ninja Turtle. Then you will probably be roasting at around level 2.5.

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