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Roasting Beans with a Milk Powder Can


Hiroyuki

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My first attempt to roast coffee beans with a milk powder can

Nakagawa, the owner of Flavor coffee http://www.flavorcoffee.co.jp/index.html (Japanese only), is a proponent of roasting coffee beans with a milk powder can.

Today, I made my first attempt, but it ended in a failure; the beans didn't crack even after 25-minute roasting. I think that the main reason of my failure was that I did the roasting outside and it was rather windy. :sad:

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More text later.

Edited by phaelon56 (log)
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I think you're correct that the wind and ambeint outdoor temperatures may have been a factor but there's more to consider. Coffee beans can be roasted by conducted heat (i.e. from the hot metal surface of the milk powder can or from contact with a metal roasting drum), by convected heat (hot air moving across and through the beans) or by a combination of the two.

Most of the popular consumer style commercial home coffee roasters operate on a principle similar to hot air popcorn poppers. Hot air is created with an electric heating element and a fan moves the hot air up through the roaster (people actually do use hot air popocrn poppers for this purpose as well). There are vanes that direct the air to move in a circular motion - this creates a swirling updraft that suspends the coffee beans in the hot air and constantly recirculates them in a flowing motion so that they move in and out of and back into the hottest area closest to the heat source. The chaff blows off the beans during this process and either blows out the window or into the air nearby depending on where you're roasting (most of the consumer hot air roasters have a screen or filter that collects most of the chaff to eliminate messiness.

Peopel can and do roast beans by methods as simple as heating them in a cast iron skillet on the stovetop or using a commercial heat gun and a large stainless steel bowl (called the "dog bowl heat gun" school of roasting :biggrin: ). These methods rely on conducted heat and it's crucial to stir/circulate the beans constantly by stirring them.

It appears that your can needs larger holes to allow more heated air to move in but it would also help if there was some sort of a fan that was blowing air up into it to get the beans at least partially suspended by air and moving.

Did you have the burner heat at the maxiumum setting? Ensure to do that and you might also try a slightly larger amount of beans. It may seem counter-intuitive but a slightly larger amount of beans may actually shorten the roasting time on some systems because the larger mass of beans means more accumulated mass of heat in one place - this can speed up roasting by a bit.

With proper technique, a method of roasting such as the one you picture should be able to get a good roast level with about 20 minutes of roasting time. It's best not to exceed that lenght of time by much.

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Thank you, phaelon56, for your comments.

This is not my method but Nakagawa's and a tried and tested one. In fact, he fully explains how to make this roaster http://www.flavorcoffee.co.jp/flavor3.html and how to operate it http://www.flavorcoffee.co.jp/flavor3b.html (both in Japanese only) on his Flavor coffee website.

I had read all threads on popcorn poppers in the Coffee and Tea Forum. The problem that I have with them is that they are not readily available in Japan. Yet, all that talk about superheated steam roasting and Matsuya paper dripping had made me want to roast coffee beans once in my lifetime. So, I asked Nakagawa to make me a milk powder can roaster free of charge. (I spent 6,100 yen to send you the coffee beans and I have the right to ask him that, don't you think?) You may not believe this, but this roaster is one item that Flavor coffee sells; a set of this roaster and 1-kg green coffee beans is sold for 5,000 yen. It was kind of a joke for Nakagawa, but quite surprisingly, it sells!

I will submit another post as soon as I succeed. If operated properly, this roaster yields beans just like these:

gallery_16375_5_1097182665.jpg

Photo on the left: Beans roasted with this roaster

Photo on the right: Beans roasted with a commercial roaster

You can't tell the difference, can you?

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Today, my second attempt ended in a failure too.

I did the roasting indoors and I always kept the heat high, so that the beans were almost burned in only four minutes.

gallery_16375_5_1097812841.jpg

Anyway, I drank the resulting coffee. It found it rather bitter, but drinkable contray to my expectation.

I have learned lessons from my two attempts. I hope that my third attempt will turn out to be a success.

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Hiroyuki - How are the beans moved or circulated during roasting - do you stir them? I think you're on the right track but need to adjust or modulate the temperature.

An ideal roast time for most beans will be about 12 - 14 minutes but an easy and repeatable way to get the results you seek is to deploy a thermometer that is measuring the temperature within the moving beans. Most home roaster typically deploy a simple and inexpensive analog dial thermometer such as the

Cooper 550 degree large face dial thermometer

It doesn't matter what brand you use and it needn't actually have a large face as long as you can read it. The way to achieve easy repeatability is to take the beans to a certain temperature over a given amount of time. I suspect that on your next attempt you'll get something that turns out well. Reduce the heat, agitate the beans and watch the progress. At about the five minute mark they should be turning a golden yellow color and by the eight or ten minute mark developing a light brown color. A few minutes later you should hear a cracking sound start that is known as "first crack". It sounds like popcorn popping - the sounds are relatively loud, at intermittent intervals and of varying volume levels. If you have temperature adjusted properly the first crack will subside and after a short period of time with only a few cracks heard during the interval, the "second crack" phase starts.

At this point the cracks are much faster (closer to one another in succession) and more like the sound of twigs cracking. A nice medium roast is typically one that is stopped at the onset of second crack. A medium dark roast usually goes ten to twenty seconds into the second crack stage (before beans are removed from heat) and anything beyond that will result in a dark roast. Many novice roaster also find it easy to judge roast level by color. When the beans have reached a color that is just a little bit lighter than the desired final roast color it's tiem to remove them fromt he heat and cool. The beans still cook and change internally until the temperature is reduced so it's important to cool rapidly. Most find that using two colanders to pour the beans back and forth is an effective method.

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Hiroyuki - How are the beans moved or circulated during roasting - do you stir them?  I think you're on the right track but need to adjust or modulate the temperature.

Wow, thank you for all of your suggestions. You must be very busy just before the opening of the new shop!

I shake the can constantly as instructed on that webpage of Flavor coffee.

With your suggestions, I really hope my third attempt will be a success.

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The answer is:

The milk powder can is not coated on the inside, so that no coating burns when the can is heated.

from here:

http://www.flavorcoffee.co.jp/flavor3.html

(Japanese only)

I have no intention of becoming as coffee-geeky as phaleon56 or Nakagawa of Flavor coffee is :biggrin: , but I want to get a general idea of how coffee beans are roasted. This is very interesting especially because what roasting does to coffee beans reminds me of what fermentation does to soy beans, but in a very short time, 14 to 16 minutes.

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Have you seen this site with various homemade roasters?

"There are, it has been said, two types of people in the world. There are those who say: this glass is half full. And then there are those who say: this glass is half empty. The world belongs, however, to those who can look at the glass and say: What's up with this glass? Excuse me? Excuse me? This is my glass? I don't think so. My glass was full! And it was a bigger glass!" Terry Pratchett

 

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I have a "vintage" popcorn popper identical to the one on this link and it says

Popcorn Popper or Coffee Roaster for the stove top, electric or gas.

Whirly Pop

I know a lot of people who buy these only to use as a coffee roaster. They work very well on an electric hot plate as well as a gas burner but most of the people I know that use them prefer an electric hotplate.

I am pretty sure they are available in Japan because one of the lab technicians who works in the office went to Japan for a class last spring and forgot his coffee roaster. He was going to have his girl friend send his but then told her not to bother he found one.

He came home in August and apparently left it with his hosts, having initiated them into the joys of freshly roasted coffee. He stayed in Kyoto and probably didn't travel too far to shop.

"There are, it has been said, two types of people in the world. There are those who say: this glass is half full. And then there are those who say: this glass is half empty. The world belongs, however, to those who can look at the glass and say: What's up with this glass? Excuse me? Excuse me? This is my glass? I don't think so. My glass was full! And it was a bigger glass!" Terry Pratchett

 

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Very interesting, thank you for the link!

So many coffee geeks, and so many techniques!!

I am amused to find, in the Home Roasting in Japan section in the link, the very same photo of a milk powder can as that shown on Flavor coffee's website.

I think I will stick to this low-tech method for now. I may move on to a more sophisticated method later on.

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Today, I made my third attempt outdoors. I carefully watched the beans while constantly shaking the can so as not to overheat them. In fourteen minutes, I stopped roasting. It looked like a success.

gallery_16375_5_1098071632.jpg

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Although the beans looked good in color, I found the resulting coffee lacking in aroma and flavor. This is due to my lack of experience in roasting rather than the characteristics of the milk powder can roaster. On Flavor coffee's website, Nakagawa says that the roaster can make roasted beans comparable to those made with a commercial roaster. I know I have to improve my roasting skills.

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I think you're very close to success. The beans still look slightly under-roasted. Did you listen for the cracking sounds of first crack and second crack? Roasting time could be anywhere from 10 to 16 minutes and still deliver pleasing results but if you don't reach at least the completion of the first crack stage or better yet get to the start of second crack... you'll be under-roasting. If the beans taste flat and perhaps almost on the grassy side it means they still weren't roasted to the right stage.

You may need to increase the heat just a small bit.

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Did you listen for the cracking sounds of first crack and second crack?

I started to hear the sound of first crack as early as six minutes after I started roasting, so I had to keep the can away from the heat for some time. I don't think I heard the sound of second crack. I thought right at the beginning that I would stop roasting in fifteen minutes. I think you are right – the beans were under-roasted. Next time I think I will keep roasting until I hear second crack.

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Peopel can and do roast beans by methods as simple as heating them in a cast iron skillet on the stovetop...  ...These methods rely on conducted heat and it's crucial to stir/circulate the beans constantly by stirring them.
is there any reason why more people dont use a skillet? is it bc its simply more difficult to roast in a pan?
"Bibimbap shappdy wappdy wap." - Jinmyo
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I agree with Owen's comments. The beans look under-roasted to me. I would try perhaps a higher temperature and more time. If the coffee does not reach a complete first crack or the beginning of second, it will probably taste relatively insipid.

Regards,

Michael Lloyd

Mill Creek, Washington USA

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is there any reason why more people dont use a skillet?  is it bc its simply more difficult to roast in a pan?

I can tell you that it's impossible to stir the beans in a skillet as constantly and violently as in a can roaster.

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How to make a can roaster

based on http://www.flavorcoffee.co.jp/flavor3.html

Parts:

1 milk powder can, 13 cm (5.1 in.) in diameter and 18 cm (7.1 in) in height

1 wooden stick, 17 to 20 cm (6.7 to 7.9 in.) in length, for use as a handle

2 stainless steel bolt, 6 mm (0.24 in.) in diameter; one 7 to 15 cm (2.0 in.) in length and the other 16 to 20 cm (6.3 to 7.9 in.)

8 nuts (or 12 if attaching an optional heat shield)

Optional: 1 metal sheet, 10 cm (4.7 in.) by 30 cm (11.8 in.), for use as a heat shield

Tools:

Hammer

Nail, 2 to 3 mm in diameter

Drill

Punch

Note: If the can is coated on the inside, burn the coating off before use.

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Procedure:

1. Make 31 holes on the bottom of the can:

a. Determine the center of the bottom of the can.

b. Draw 3 concentric circles with 2, 4, and 5.5 cm (0.8, 1.6, 2.2 in.) in radius.

c. Using a punch, mark 6, 12, and 12 equally-spaced hole centers along the circumferences of the respective circles, and 1 at the center of the bottom, thus 31 in total.

d. Make holes, using a hammer and a nail, NOT a drill, from the OUTSIDE.

The reason for this is to make burrs on the inside of the can, which facilitates chaff removal.

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2. Attach a handle and a heat shield (optional):

a. Using a drill, make a 6 mm (0.24 in.) diameter hole at a location 1 to 2.5 cm (0.4 to 1.0 in.) apart from the bottom of the can and another at a location 3 to 5 cm (1.2 to 2.0 in.) apart from the top.

b. Bend the metal sheet at a right angle along the 18 cm (7.1 in.) line from the top.

Sorry, no more details. Please refer to the drawing below.

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gallery_16375_5_1098182323.jpggallery_16375_5_1098182488.jpg

Edited by Hiroyuki (log)
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Very interesting! Do you have a dial or IR thermometer to keep track of the roasting temperature? Along with other factors, this will help you in achieving the degree of roast you have and aid you in duplicating your roast in the future. It certainly helps in my roasting (I use a modified popper and have since chucked my FreshRoast).

I am intrigued with this milk can method. Will it work with a camping stove that uses white gas, I wonder?

By the way, second crack occurs around 415 to 435 degrees F (bean temperature), resulting in a regular city roast. But this depends on a multitude of other factors.

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Very interesting! Do you have a dial or IR thermometer to keep track of the roasting temperature? Along with other factors, this will help you in achieving the degree of roast you have and aid you in duplicating your roast in the future. It certainly helps in my roasting (I use a modified popper and have since chucked my FreshRoast).

I am intrigued with this milk can method. Will it work with a camping stove that uses white gas, I wonder?

By the way, second crack occurs around 415 to 435 degrees F (bean temperature), resulting in a regular city roast. But this depends on a multitude of other factors.

Quite frankly, I can't answer your questions. I'm sure you know more about roasting and coffee in general than I do. I'm a beginner... :sad:

I'm interested in your modified popper. Perhaps you could post a photo of it along with a brief description. :biggrin:

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How to use the can roaster:

based on http://www.flavorcoffee.co.jp/flavor3b.html

Requirements:

Stove or portable stove

Roaster

Fan

Stainless steel strainer

Cotton work gloves

Stopwatch (not shown in the photo)

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6 minutes later

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9 minutes later

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Control the heat so that first crack occurs 15 minutes later

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Radiator fan that Nakagawa of Flavor coffee made especially for me, so powerful that it cools just-roasted beans in less than five minutes:

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Text later.

Edited by Hiroyuki (log)
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congratulations are in order!  very tenacious.  that cup must have been so satisfying in more ways than one.

the radiator fan.  do you attach it somewhere?  looking forward to the text additions.

Thank you, melonpan.

You just place the roaster on top of the radiator fan, like this:

gallery_16375_5_1098441994.jpg

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