Roast Approach: India Kerehaklu Estate S9 Lime Cultured Washed

Today's coffee that we are going to approach is a fresh crop (2025) from Kerehaklu Estate in India.  This coffee is a washed coffee with a lime culture added during processing.

 Arrival QC and Sample Cupping:

• Harvest date: March 2025

• Arrival date: August 2025

• Moisture content: 11%

• Density: 1.15 g/ml

• Altitude: 1025-1175 m.a.s.l.

• Cup score: 86

Initial QC Cupping:

Fragrance and aroma of lychee, juniper and florals. Notes of white tea and dark chocolate with an aftertaste of lime zest and florals. Bright malic and tartaric acidity with a medium body and tea-like mouthfeel.

The Coffee:

At Kerehaklu Estate, Pranoy isolates local microbes and cultures them. This enables Pranoy to control which microbes are dominant during fermentation while still preserving the estate’s ecological fingerprint. This “blossom culture” is added to the coffee while it undergoes submerged fermentation for 36 hours. The Kerehaklu Estate is located within 250 acres of the Western Ghats, a 1600km mountain range in western India that has been recognized by UNESCO as a world heritage site for its biodiversity.

The varietal grown for this lot is the S9 (Select 9), which was developed in India as a hybrid of the HdT (Timor Hybrid) and the Ethiopian Tafarikela variety.  This variety is noted for having cupping notes that typically include apple, citrus, caramel and nut. It is most commonly found grown in India.

The Roaster:

For these roasts, I'll be using a Proaster 1.5 kilo drum roaster hooked up to natural gas.  Batch size is 400g, approximately 35% of roaster capacity.  I've used a small batch size on this roaster to get closer to mimicking the gas power that you might find on a larger production roaster.  It must always be mentioned that each roaster is different.  The type of probe, placement of probe, and batch size will all influence the way in which bean probe temperatures are registered in a roaster.  With that said, don't read too much into the exact temperatures, but look more closely at the theory behind the approach, time spent in different development periods, and rate of rise to get a better idea of how to translate this profile over to your own machine.  

The Goal:

In this edition of Roast Approach, I will bring you four different roasts of this coffee.  Each roast providing a unique emphasis to the acidity, sweetness, body and balance of the coffee.  Hopefully this will provide you with the background you need to confidently approach this coffee in your own roasting adventures.

If you would like to learn more about my four phase approach to roast profiling, check out my “Roast Approach: Roast Strategy” blog.

Below is a comparison chart of the four roasts for you to follow along with. Each segment is measured in seconds with drying from charge through 305, Maillard from 305-350, caramelization from 350-first crack, and post crack development time measured from first crack through the end of the roast.  This coffee entered in to first crack usually around 385.  Due to first crack being prone to some inconsistencies, I have adjusted all measurements of post crack development time to go from 385 degrees through the end of the roast.

The Approach:

Roast PR-18975 - "The Standard"

This particular roast profile is what I consider my "standard."  It's the base profile that I use on my first attempt at any coffee.  I start the coffee at a moderate charge temperature of 390, gradually increase the gas application up through caramelization, then gradually step down the gas application after first crack.  I also use a standard gradual increase in airflow, which you'll see echoed in all of my roast profiles.  This coffee ended at 402.8 degrees and a total roast time of 8:41 minutes. Roast loss was 13.13%.

When I roast this first "standard" my goal is really to observe the coffee and see how it is reacting to heat.  I am specifically looking at my rate of rise during Maillard and caramelization phases.  While I pay attention to first crack, I find that it can be an inconsistent metric.  What I am really watching for is how the coffee reacts to the drop in gas application and increase in airflow around first crack.  A plummet in my rate of rise around this time in the roast signals to me how much momentum I may need to achieve my goals in future roasts.  Lastly, I am watching for points at which the bean becomes exothermic and my rate of rise increases.  I make note of these temperatures so that I can adjust gas application in future roasts accordingly.  In roasting this coffee from Karahaklu Estate, I did not encounter any "take off" or "crash out" events during the roast.  The coffee roasts similar to washed central.  In comparison to the blossom culture lot from Karaheklu Estate, I found the lime culture to be a bit easier to roast because it didn't have any particular events that needed to be navigated.  

The Cup:

On the cupping table, this coffee had a fragrance of sweet limeade, green apple and nuttiness.  Tasting notes were of green apple, limeade citrus acidity, dark chocolate and red berry.  The body was medium and juicy.

The Approach:

Roast PR-18976 - "Hot & Fast"

For this second roast, my goal was to see how the coffee responded to heavy gas application through both Maillard and caramelization phases.  An increase in gas application was started early (around 240 degrees) with full (100%) application by the start of early Maillard.  This 100% level of gas was maintained until right before first crack, at which point it was gradually stepped down.  The intense gas application created shorter periods in Maillard and caramelization, with drying being nearly the same.  With the increased heat also came increased momentum and a shortened period in post crack development time.  This coffee ended at 402.3 degrees and a total roast time of 7:04 minutes.  Roast loss was 12.13%, exactly 1% more than the previous roast (PR-18975).  Note that these two roasts finished at the same temperature, but with a total roasting time difference of 1:13 minutes.  

The Cup:

On the cupping table, the coffee had an aroma of lime, green apple and key lime pie.  The coffee had tasting notes of green apple candy, lime acidity and a sweet finish.  The body on this coffee was creamy, silky and clean.  

The Approach:

Roast PR-18973 - "Fast Then Slow"

For the third roast, I wanted to try to stretch out the caramelization phase of the roast and develop more complexity in the sugars. I also wanted to keep the high gas application, with hopes of creating a coffee that was complex, sweet, and balanced.  To accomplish this goal, I used the same heavy gas application as in the previous roast, however I backed off the gas application substantially before the caramelization phase started.  You will see from my roasts that I frequently make the adjustments 10-15 degrees in advance of the start of the expected chemical reactions, so that at the beginning of those chemical reactions, the roaster has adjusted to provide the energy catalyst that I am looking for.  Any time that I am looking to stretch out caramelization, I have to be mindful of my end temperature.  More time in caramelization can build mellanoidins and complex sweetness in the coffee, but it also means less momentum through post crack development.  If you try to achieve the same end temperature, you'll bake your coffee.  To adjust for this, I typically look at reducing my end temperature by about 2 degrees.  This coffee ended with a temperature of 400.3 degrees and a total roast time of 7:24 minutes.

The Cup:

On the cupping table, the coffee had a fragrance of key lime pie, coconut, and fresh cream.  The aroma had a lot of sugar browning character, with the aroma of chocolate, brown sugar, and meringue. In the cup, the flavors were of caramel, butterscotch, lime zest, and pastry cream with a lactic acidity.  The coffee was incredibly balanced with a creamy silky body and sweet finish.  

The Approach:

Roast PR-18978 - "The Slow Snail"

For the final roast, I am looking to see how the coffee reacts with a slow trip through Maillard and caramelization.  For this roast, I also started with a lower start temperature of 383 degrees.  Additionally, I took the coffee to 403 degrees for an end temperature.  This is typically how I would begin to approach a medium or dark roasted coffee where I was seeking to tone down some of the acidity and emphasize sugar browning sweetness.  This coffee finished at 403 degrees and an end time of 8:42 minutes.  You'll also notice that this roast has the highest percentage of roast loss, with a roast loss of 13.38%.  It's notable that this coffee is significantly more "developed" tasting, with muted acidity and complex sugar browning character and does not have a drastically different roast loss difference than the first roast.  This difference in flavor from the first roast, with a nearly identical roast time and similar roast loss, is due to a longer proportion of time spent between 350 degrees and the end of the roast.  This emphasis on the chemical reactions associated with the Strecker degradation and caramelization have a significant impact on the flavor in the cup.

The Cup:

For this final coffee, the aroma was full of sweet toasted coconut, orange blossom, lime, and graham cracker.  The cup notes were of dark chocolate, lime, and buttery pastry.  The body of this roast was fuller and heavier than the previous roasts, but did have some "grit" to the mouth feel.   

The Takeaway:

This coffee may be one of my favorite coffees that I've roasted in a long time.  The coffee is a dream to roast, predictable and without any twists or turns during the roast.  When I brought the samples to the cupping table, they were all excellent.  No matter what I changed in the roast, the sweetness and balance of the coffee shined.  The coffee is exceptionally sweet and would easily lend itself to espresso extraction and any kind of milk based beverage.  

Between all of the roasts, I think my personal favorite was the "Fast then slow" approach.  I loved how sweet this particular roast of the coffee was and how creamy the body was.  This was a coffee that I could drink every day.  I was also a big fan of the second "Hot & fast" roast of this coffee, which gave more complexity in the acidity and fruit character of the coffee.  

As I researched the S9 (Selection 9) variety, I thought it was very interesting how closely this coffee echoed the archetype flavor call outs of apple, citrus, caramel sweetness, and nuttiness for the variety.  I hope you enjoy this coffee as much as I did.  

Happy Roasting!