Q&A Coffee Podcast with Scott Rao

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**Q&A Coffee Podcast with Scott Rao**

Beginner and advanced questions about coffee brewing and roasting.

Latest Episodes:

seraphim at revolver.JPG — **What are the best dose and brewing ratio?** Feb 05, 2020
Show notes

How should you determine the optimal dose and brewing ratio for espresso or filter? Ongoing conversations I’ve been having with Jonathan Gagné and the recently published piece of espresso research by Chris Hendon et al, have been keeping this issue top of mind. I hope this post will provide readers with food for thought when making brewing decisions.
Rather than always relying on standard, popular ratios (eg 2:1 for espresso, 17:1 for filter), I recommend baristas consider a few factors when deciding on a ratio for a brewing method.
**Desired TDS and Extraction Yield:** each particular combination of EY and TDS can only be achieved by a unique brewing ratio. If for some reason you desire a specific TDS and EY combination, such as 1.4% TDS and 22% EY, there is only one ratio that can produce that pair of numbers. This also means that you may want to use different brewing ratios with different grinders. I recently brewed the same coffee as a v60 on my DE1 using two different grinders; one grinder achieved 24.5% EY/ 1.6 TDS. The other grinder could achieve only 21% EY/ 1.4 TDS. If my goal is to always have a TDS of 1.4 at the highest possible EY, I would consider using a higher brewing ratio with the first grinder.
**Channeling:** In percolation methods, it’s important to use a ratio that won’t lead to noticeable channeling or astringency. In espresso brewing, better puck prep will allow a barista to use a higher ratio (say, 3:1 as opposed to 2:1) without channeling. If you have poor puck prep, or if your grinder produces a lot of clumps, you may want to consider decreasing your brewing ratio to avoid astringency due to channels. In drip brewing, the more evenly you spray or pour the water over the coffee bed, the less channeling will occur. The more evenly the water extracts from the coffee bed, the higher the ratio (within reason) you can use without channeling.
**Bed Depth:** Whether pulling an espresso, brewing in a v60 or using a Fetco, each basket you use has an optimal range of bed depths. Batch brew bed depth should typically be 3cm—5cm. A device such as a v60 generally brews best in a range of 15g—22g of coffee (5cm—6 cm.) Coffees of extremely high or low density may require small adjustments in dose to maximize extraction. Note that many cafes that serve two-liter batch brews use baskets designed for larger brews. If you brew two-liter batches, the smallest-diameter baskets available for your batch brewer may help to increase the bed depth of your doses into the recommended range.
**Flavor defects** If you’re brewing a defective or poorly roasted coffee, you may improve flavor and mask some of flavor defects by lowering your ratio and extraction level. Intentionally underextracting charred, baked, or underdeveloped coffee can sometimes make it more palatable.
**Beverage Sizes** When planning a dose and ratio for espresso, it’s important to consider the sizes of your milk drinks, and how much total dissolved solids your shots will contain. For example, a 15g dose at 22% extraction would provide 3.3g of dissolved solids, while a 22g dose at a more modest 22% would provide 4.84g solids. While the 15g dose may be appropriate for a cappuccino or a cortado, its 3.3g of dissolved solids would nearly disappear in a 12oz latte. The 22g shot may be just right (for some) in the latte. Some cafes choose to use larger (20—22g) doses and to “split” the shots so they can use a single shot for straight espresso and very small milk drinks and two shots for larger milk drinks.
Do you have some thoughts on other factors to consider when determining a dose and brewing ratio? Please share your thoughts in the comments section. Thanks for reading.

split shot.jpg — **Australian and American coffee bars: Their differences, and what they can learn from each other** Dec 22, 2019
Show notes

There are two significant differences in how third-wave baristas serve coffee in the US and Australia. I believe if baristas in each country adopt the other’s practices, it would improve labor efficiency and speed of service in both countries.
Batch brew makes up perhaps 40% of coffee orders in the US, but less than 5% in Australia.
Most Australian baristas “split shots,” while few Americans do.
I believe Australian and American cafes could benefit from adopting some of each other’s practices.
Batch Brew
The obvious benefit of batch brewing is it requires much less time and labor to serve. Given the high cost of labor in Australia, many cafe owners have expressed a desire for customers to embrace batch brew. Unfortunately, customer acceptance has been slower than many in the Australian coffee industry would like. While I’m not an expert on the Australian market, I’d like to make a few suggestions to help customers warm to batch brew:
*Do it well.* Unfortunately, the popular Aussie choice to use a Moccamaster in a cafe is not good enough. Moccamasters do a poor job of achieving even extractions, and their brewer/carafe design causes excessive heat loss during brewing. That heat loss, compounded by suboptimal brewing-water temperature, greatly accelerates the aging rate of the brewed coffee. (If you must use a Moccamaster, please use the commercial version with the round spray head and find a way to prevent heat loss from the carafe during brewing.)
*Don’t serve old coffee.* Most Australian third-wave cafes that serve batch brew hold the brewed coffee too long (as do most Americans). Serving two-hour old batch brew is not going to win converts. I feel for Aussie cafes here: batch-brew machines are generally designed to brew at least two liters at a time, but the cafes don’t serve enough batch brew to brew that much coffee without having to pour most of it down the drain. (The good news is I believe in the next year there will be at least two new batch brewers designed to produce excellent batches smaller than two liters.)
*Talk it up.* Explain to customers that batch brews offer great extraction quality. Give them free samples while they wait in line, especially to those who order long blacks and americanos. Offer an interesting coffee exclusively on batch brew. Hold events featuring your best coffees on batch brew. Familiarity is the key to acceptance.

Splitting Shots
Italian espresso developed around small doses of 7-ish grams and beverages no larger than 150ml (5 ounces). In the 90s many specialty-coffee markets adopted larger drinks sizes, which require significantly larger doses. For example, if you’re a Starbucks barista serving 20oz (600ml) lattes, it would be reasonable to use doses of 20g or more. (Note: I do not know what dose size Starbucks uses.)
Australians have never warmed to the massive beverage sizes common in North America. Aussie cafes generally serve Italian-sized beverages with the occasional 250—350 ml (8—12oz) caffe latte on the menu. Serving smaller-sized drinks has allowed many Australian coffee bars to split shots, or pull two shots from one portafilter. In a country where few customers order batch brew and almost every coffee is espresso-based, splitting shots is critical to enhance efficiency and control labor costs. Of course, a few third-wave American cafes split shots, and a few Australians don’t, but they are exceptions to the rule.
Specialty shops in the US used to serve a variety of larger beverages, using massive espresso doses. However, as US third-wave shops have gradually adopted the smaller sizes common in Australia, American baristas now have a chance to improve efficiency by splitting shots, and, I believe, improve many beverages. I hope some US third-wave shops will consider splitting shots; as beverages have shrunk and extractions have increased, split shots have become more appropriate than they used to be. Half of a 20-gram dose is plenty for a straight shot of espresso, a 5-oz (150ml) cappuccino, a macchiato, and most hipster-sized drinks (cortados and gibraltars). The full 20g dose is plenty for a 12-oz latte, if a cafe chooses to serve one beverage that large.
The Upshot
While this post isn’t revelatory to anyone who has ordered coffee around Australian and the US, it does bring up some potential ways each country can benefit from the other’s practices. The part of the American market that offers smaller beverages is ready to split shots, which will cut coffee costs and improve labor efficiency and speed of service. Australian baristas have a chance to introduce their customers to batch brew at its best, which would greatly cut labor costs if widely adopted. But winning customers over to batch brew may require best practices and greater familiarity: Brew small batches in quality brewers. Brew into enclosed, appropriately sized thermal carafes with “brew-through” lids to conserve heat. Never brew more than one coffee at a time or two liters per batch. Ditch brewed coffee before it tastes sour and bitter. Feature batch brew at tasting events and demonstrations. Gently familiarize customers with batch brew.

me at CRS Sydney.jpg — **ONLINE ALL-LEVELS ROASTING CLASS + FORUM** Nov 23, 2019
Show notes

I’m pleased to announce I will offer an online roasting course on January 4th, 2020. The class will be broadcast through a private Facebook group. All ticket holders will have access to the class video and discussion forum for one month after the class airs. Many students of previous online classes have said the month-long discussion forum improved their roasting more than any other class or resource.
**Please note that it is not necessary to view the class when it airs live.**
All ticket holders will have access to the class and forum for one month. During that month you can view the class as many times as you would like.
Please join us online, or if you’re in Southern California, we’d love to see you in person. Live seating will be limited, so claim your seat ASAP. The class will be held at Common Room Roasters in Costa Mesa from 1pm—4pm.
All ticket holders, live and virtual, will have access to the class video for one month through Facebook.
**ONLINE CLASS ACCESS WILL BE FROM JANUARY 4 -- FEBRUARY 3, 2020**
All ticket holders will also have access to a discussion forum on the private Facebook group for one month. I will field questions and comment on students’ curves every day on the forum. The forum will provide a safe, friendly space for a high-level discussion about roasting, something difficult to find anywhere else. Students of past online courses have found the forum helpful for solidifying the class lessons, have enjoyed the community feeling, and many have shared their roast-curve progress on the forum.
The course will be appropriate for roasters of all levels. Although I am calling it an “all levels” class, this course will touch on methods more advanced than anything in the level-three SCA roasting course (even their “advanced” classes are basic), and I guarantee your satisfaction.
The class will include:
Three hours of lecture and Q&A
Cupping and curve analysis of the "Roast Defect Kit" featuring good, baked, and underdeveloped roasts.
Methods to manage ROR curves
Advanced methods to prevent ROR crashes and flicks
How to modify roasting machines for better performance.
Pro tips to get the most out of Cropster and other roasting software.
How to adapt various strategies to different types of machines.
Online tickets are $125 USD, live tickets are $175. During the class we will cup samples from the upcoming Roast Defect Kit. If you buy a virtual ticket and would like to receive the Roast Defect Kit in the mail to cup along with us at home, the kit will cost an additional $50 USD (making online and live tickets the same price.) The RDK is a great educational tool to share with your coworkers or staff. (Note: we are sorry but cannot ship the RDK to South Africa, China, Russia, Greece, or Brazil.)
**Click** **here** **to purchase class tickets and the RDK**.

4.1 drum RPM chart.jpg — **TUNING YOUR ROASTING MACHINE** Nov 23, 2019
Show notes

The vast majority of machines I’ve worked on in my consulting career have needed what I call “tuning.” For example, just this past month, a client with a new Probat had far less airflow than he needed, due to his chimney configuration. Two experienced clients were operating with less than half of their respective machines’ optimal gas pressures. Several clients were operating machines with suboptimal drum RPMs or airflow levels. One client had both inadequate gas pressure and inadequate airflow, caused by an air leak at the loading funnel. Several roasters were using excessive software smoothing or slow thermocouples.
Proper gas pressure, drum RPM, airflow level, probe size and location, and software settings are all necessary before one can roast great coffee with impressive consistency. My experience implies that most roasters reading this post likely have tuning problems of which they are not aware. All of the issues below can be remedied quickly or cheaply. Fixing any of them will provide an excellent return on the invested time or money.
Gas Pressure
Every gas burner is designed to work safely and efficiently in some range of gas pressures. For example, your machine’s manufacturer may recommend a range of 3–5 kpa (12–20 inches of water column). The recommended range should be listed on a badge on the side of your roaster or on the manufacturer’s website. What almost no one tells roasters is that pressure at the top of the recommended range offers a lot more power and efficiency than pressure at the bottom of the range. Suboptimal gas pressure forces many roasters to roast smaller or slower batches. I’ve seen increases in gas pressure lead to 50% increases kg per hour of roasted coffee.
Drum RPM
Even if your machine is brand new and the manufacturer installed it for you, check its drum RPM. A few major manufacturers deliver machines of a given model with widely varying RPMs (often a difference of 20 RPM machine to machine). Some whom I’ve asked to fix it for my client have claimed “it doesn’t matter” (one of those same manufacturers has told me that ROR crashes don’t matter, so be careful where you get your roasting advice!) Please count your drum RPM over the course of one minute. If your machine’s RPM are either too high or too low, it will cause more conductive heat damage and harsher coffee. Very low RPM can also contribute to ROR crashes.
My RPM recommendations are in the chart below. If you have a 12kg roaster with, say, 35 RPM (a frequent problem from one manufacturer), you will not be able to avoid ROR crashes and excessive conductive heat transfer. You may be satisfied with roasts from a low-RPM machine, but the coffee will be noticeably better when you adjust the RPM to the proper range.

Airflow
There are many causes of improper airflow levels in roasting: air leaks, such as loading hoppers that don’t seal well, fans spinning in the wrong direction (more common than you would think), chimneys that are too tall or have too many 90-degree angles, or simply roasters adjusting fans and dampers improperly. If your roasting-exhaust and cooling-air chimneys merge before passing through the roof it may cause back pressure in the roasting drum and shifts in roasting airflow depending on whether the cooling fan is on.
If your RORs decline with a relatively constant slope, your ET curve should stop rising somewhere just before or around the beginning of first crack (there are too many factors to be more specific here). If your ET peaks more than two minutes before first crack begins, you probably have too much airflow. If your ET curve rises all the way through the end of a roast, you are probably using too little airflow. And of course, if lots of smoke or chaff pours out of the drum when you drop a light or medium roast, the airflow is probably set too low.
Probes and Software

This probe is slow enough to make the data almost worthless.

Quality data collection and presentation are essential to quality, consistent roasting. If the turning points of your roasts are routinely later than 1:30, your probe is probably too slow. If your RORs look very noisy when viewed in the 15-second averaging interval in Cropster RI3 (or the 15s delta span in Artisan), you may have excessive noise in your system. (I covered this issue more thoroughly in my July 4, 2019 post.) If your RORs are smooth, rather than jagged, curves, your smoothing settings are too generous.
Please don’t assume that if you like the way your coffee tastes or your machine is new that it doesn’t need tuning. Few of the roasters I’ve worked with whose machines needed tuning knew there was a problem, but all were happier with their roasts after we tuned their machines.

**TUNING YOUR ROASTING MACHINE** Nov 23, 2019
Show notes

The vast majority of machines I’ve worked on in my consulting career have needed what I call “tuning.” For example, just this past month, a client with a new Probat had far less airflow than he needed, due to his chimney configuration. Two experienced clients were operating with less than half of their respective machines’ optimal gas pressures. Several clients were operating machines with suboptimal drum RPMs or airflow levels. One client had both inadequate gas pressure and inadequate airflow, caused by an air leak at the loading funnel. Several roasters were using excessive software smoothing or slow thermocouples.
Proper gas pressure, drum RPM, airflow level, probe size and location, and software settings are all necessary before one can roast great coffee with impressive consistency. My experience implies that most roasters reading this post likely have tuning problems of which they are not aware. All of the issues below can be remedied quickly or cheaply. Fixing any of them will provide an excellent return on the invested time or money.
Gas Pressure
Every gas burner is designed to work safely and efficiently in some range of gas pressures. For example, your machine’s manufacturer may recommend a range of 3–5 kpa (12–20 inches of water column). The recommended range should be listed on a badge on the side of your roaster or on the manufacturer’s website. What almost no one tells roasters is that pressure at the top of the recommended range offers a lot more power and efficiency than pressure at the bottom of the range. Suboptimal gas pressure forces many roasters to roast smaller or slower batches. I’ve seen increases in gas pressure lead to 50% increases kg per hour of roasted coffee.
Drum RPM
Even if your machine is brand new and the manufacturer installed it for you, check its drum RPM. A few major manufacturers deliver machines of a given model with widely varying RPMs (often a difference of 20 RPM machine to machine). Some whom I’ve asked to fix it for my client have claimed “it doesn’t matter” (one of those same manufacturers has told me that ROR crashes don’t matter, so be careful where you get your roasting advice!) Please count your drum RPM over the course of one minute. If your machine’s RPM are either too high or too low, it will cause more conductive heat damage and harsher coffee. Very low RPM can also contribute to ROR crashes.
My RPM recommendations are in the chart below. If you have a 12kg roaster with, say, 35 RPM (a frequent problem from one manufacturer), you will not be able to avoid ROR crashes and excessive conductive heat transfer. You may be satisfied with roasts from a low-RPM machine, but the coffee will be noticeably better when you adjust the RPM to the proper range.

Airflow
There are many causes of improper airflow levels in roasting: air leaks, such as loading hoppers that don’t seal well, fans spinning in the wrong direction (more common than you would think), chimneys that are too tall or have too many 90-degree angles, or simply roasters adjusting fans and dampers improperly. If your roasting-exhaust and cooling-air chimneys merge before passing through the roof it may cause back pressure in the roasting drum and shifts in roasting airflow depending on whether the cooling fan is on.
If your RORs decline with a relatively constant slope, your ET curve should stop rising somewhere just before or around the beginning of first crack (there are too many factors to be more specific here). If your ET peaks more than two minutes before first crack begins, you probably have too much airflow. If your ET curve rises all the way through the end of a roast, you are probably using too little airflow. And of course, if lots of smoke or chaff pours out of the drum when you drop a light or medium roast, the airflow is probably set too low.
Probes and Software

This probe is slow enough to make the data almost worthless.

Quality data collection and presentation are essential to quality, consistent roasting. If the turning points of your roasts are routinely later than 1:30, your probe is probably too slow. If your RORs look very noisy when viewed in the 15-second averaging interval in Cropster RI3 (or the 15s delta span in Artisan), you may have excessive noise in your system. (I covered this issue more thoroughly in my July 4, 2019 post.) If your RORs are smooth, rather than jagged, curves, your smoothing settings are too generous.
Please don’t assume that if you like the way your coffee tastes or your machine is new that it doesn’t need tuning. Few of the roasters I’ve worked with whose machines needed tuning knew there was a problem, but all were happier with their roasts after we tuned their machines.

Q&A COFFEE PODCAST, EPISODE 2: BREWING Aug 01, 2019

Show notes

As of today’s podcast, I ‘ve begun separating the podcasts by theme: brewing, roasting, coffee & health, etc. My hope is to help listeners decide which episodes may interest them most. Today I fielded questions with Vassily about brewing, with a few coffee-business questions in the mix as well.

EPISODE TWO (also available on iTunes):

EPISODE QUESTIONS & TIMES

Mirko Thamm (1:10)

1: concerning the CO2 level of the beans. Is it better to degas after grinding (30-45min) or to grind and brew directly after grinding. Which way will get better (sweeter or more consistent) results?

2: Sieving the grind. I sieved my grind and if I used just a small range of particles (like 400-500 micrometer) the coffee was not as complex as the whole range. Should we sieve the course particles (bigger than 500microns), the fines or just a small range? Thanks

From Jonathan Mitchell (5:20)

#1 Business - I have a few potential office/law firm clients that want to become a wholesale partner but they are reluctant to keep a grinder on hand. They want me to pre-grind the coffee. I am already a little hesitant to have my coffee represented in this area but it feels like an untapped arena and a decent source of revenue. What are your thoughts?

#2 Any tips on partnering/raising money for future expansion? I am so scared of losing ownership, as I never want to compromise profit sharing with my employees, but I am also scared to dip into my personal savings for a new shop.

Benjamin Byrd , Due South Coffee Roasters (09:55)

I have a Breville precision brewer on the way and I was wondering if you had any tips on programming it for the best results, or if the batch brew rules blog was directly applicable to it. Thank you for your time and for all you do to save the industry from underdevelopment!

Ghazi Almoayed (12:30)

Hey Scott

I have 2 questions for you about espresso brewing:

1. What are you thoughts on lowering pressure to 5 or 6 bar? Is this beneficial for better extractions + consistency regardless of roast level

2. For lighter roasts I have heard about extracting 1:3 . So 18g in with 54g out. Is this only possible with an EK grinder or can a Baratza Forte still pull this off? What sort of timings should one aim for when attempting those ratios ?

Nuno Cristiano de Sousa (19:48)

Hi Scott!

First of all, thanks for taking the time to answer questions of the community
- How do you scale up your filter recipes?

I can make my extractions pretty aromatic and balanced with a 2 pours recipe, comandante 25clicks, pouring at an average 2.5ml/sec (measured in acaia). If the flow rate is higher, the total time is lower, and that messes up the extraction.

However when I tried to scale up to 500ml/17oz, i changed the grind to 28 clicks, kept flow rate, and the average extraction time raised to 3:30.