Tag Archives: coffee

More logging… and floating math.

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Two nights ago I managed to finally get the screen that shows graphs to draw the current temperature up in the corner on top of the graph.  Most of the problem was figuring out how to convert the “float” numbers to characters.

I needed to feed this into Microchip’s Graphics Library and accommodate “unicode” characters to get the “degree” symbol on the screen eventually.  Instead of typing a string as string=”Hello There”; it ends up being string={‘H’, ‘e’, ‘l’, ‘l’, ‘l’, ‘o’, ‘ ‘, ‘T’, ‘h’, ‘e’, ‘r’, ‘e’}; which ends up being an array of character values.

A float is a decimal number.  In this case 3 digits for hundreds, a decimal position, and 3 more digits for numbers.  The sensor is kicking out two digits and I’m adding readings together, averaging them, and then rounding up or down with the extra positions in some places.  The PIC32 unfortunately does not have a floating point calculation area in its brain resulting in it “compensating” for it by automatically sliding all the other numbers around using complicated things called mantissa and a few other things I really don’t want to deal with.

The reason I don’t want to deal with them is actually NOT because it is complicated (which it is) but because since it is compensating when you divide a float it has to do MANY cpu cycles for it to compensate and come up with the answer.  It is ACTUALLY easier to multiply the float by 100, 1000, 10,000 etc and insert that number into an integer data type.  Integers can be divided, multiplied, subtracted, etc without worrying about how the numbers line up and doing crazy compensating.  They just don’t end up with a decimal.

If you have a temperature of 175.25 degrees fahrenheit you multiply it by 1000 which equals 175250.  This maintains all of  required digits as a whole number and gives extra space for “rounding” down below.

The issue with the graphics library you need to use a font for every character and take into consideration symbols like degrees etc.  This means it is not simply just a “character” but you need to allocate for all the extra stuff.  This results in a larger space for each character.  To me it looks like a single character in XChar is actually two positions instead of one to leave extra room for the fancy characters to be allowed for.  To convert text strings or float numbers into characters that can be handled by the library you have to load them into an array.  This array to convert the above number (float averaged=175.25)  looks something like this:

int showtemp[8];
showtemp[0]=averaged*1000; //175250

showtemp[1]=showtemp[0]/100000; //175250/100000 = 1 in integer
showtemp[2]=showtemp[0]/10000-(showtemp[1]*10); //175250/10000 = 17.  and then 17- 1*10 = 7 in integer
showtemp[3]=showtemp[0]/1000-(showtemp[1]*100)-(showtemp[2]*10); 175250/1000 = 175 and then 175 – 1*100 – 7*10 = 5
showtemp[4]=showtemp[0]/100-(showtemp[1]*1000)-(showtemp[2]*100)-(showtemp[3]*10); // etc
showtemp[5]=showtemp[0]/10-(showtemp[1]*10000)-(showtemp[2]*1000)-(showtemp[3]*100)-(showtemp[4]*10);

temperaturetext[0]=showtemp[1]+48; // 1 + 48 = 49 = proper number for 1 in character
temperaturetext[1]=showtemp[2]+48;  // 7+ 48 = 55 or proper number for 7 in character
temperaturetext[2]=showtemp[3]+48; // etc
temperaturetext[3]=46; // 46 = proper number for a decimal.
temperaturetext[4]=showtemp[4]+48;  //etc
temperaturetext[5]=showtemp[5]+48;  //etc

 

the results in temperaturetext looks like {‘1′,’7′,’5′,’.’,’2′,’5′}

I roasted twice now using the new graph with actual temperatures listed up top and was planning on comparing the results but I accidentally corrupted the first file.  I’ve got one more batch of some coffee from Rwanda that I was testing with.  I’m getting pretty close to running out of coffee again so it’s time to order some more soon.  I was hoping to have something good from Ethiopia come up for sale but it’s still a little early for that.

Still working on… recognizing temperatures for various(rough) stages the roast is at vs some sort of mechanism to confirm a stage marking things like first / second etc.  Also need to get ambient weather information recorded and get other sensors going on it…. and make it pretier…. and of course get it hooked to higher voltage turning on and off the heat.

Modified Thermometer Test w/ Rwanda Gkongoro Nyarusiza

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So as mentioned previously I took the thermometer probe and used one of those pipe cutters with the “wheel” for cutting things like copper pipe and sliced off part of the probe.  Due to the fact that this sort of cutter “crushes” slightly while it cuts this ended up making it so I could not slide the inner electronics out without fear of not getting it back in or damaging it (without having a soldering iron currently).  I instead slid all of the formerly connected probe upwards and taped it to the probe’s plug using electrical tape.  I then crimped the remaining probe in place at the top against the braided cover.

My initial test seems to have yielded a technically proper heat ramp based on what was happening.  Additionally the cooling cycle appears to have been pretty normal too.  It appears that when the cool cycle halts the beans are approximately 158 degrees and linger there while in the roasting chamber even when removed from the roaster.  They drop to around 130 degrees after being dumped out into another container within about 20 seconds and then they hang around 130-120 degrees for several minutes if undisturbed.

Here is my heat readings for a standard roast.  In this case I was roasting the Rwanda Gkongoro Nyarusiza.

Markers are A= Rolling First Crack, B= Second Crack.  Fan speed is shown as 100% for the knob being set all the way to the right.  50% is fan knob set in the middle position (straight up).

I was not able to keep track of any additional details due to manually tracking the roast on paper.  Cooling with fan speed increased to 100% starting at 6.1 was as follows:

Bean mass started at 120g and reduced to 102g for a loss of 18g or 15%

Java Kajumas Organic Wet-Hulled Initial Roast

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Java Kajumas Organic Wet-Hulled Initial Roast

  • 7.0 to 4.3 – Minimal churn.
    • Low Heat
    • 100% Fan
    • 7.0 = Dark Green
    • 6.0 = Medium Green
    • 5.6 = Yellow Brown Green
    • 5.1 = Cardboard Brown
  • 4.3 Single FC – Low churn.
    • Set High Heat
    • Set 75% Fan
  • 4.0 – Chocolate Brown
  • 3.8 – Dark Chocolate
    • Set 50% Fan
  • 3.2 – Substantial FC pop
  • 2.8 – Rolling FC
  • 1.0 – End FC
  • 0.2 – Begin rolling 2nd cracks.
  • 0.0 – Automatic switched to Cool.
    • Cool
    • Set 100% Fan

Aroma: Initial aroma grass, popcorn.  24 hr aroma – Sesame Oil, Grass, faint vinegar.
Chaff: Extremely minimal.

Scoops: 3

Notes: For 4 scoops add approximately .5 to all times.

Ethiopia DP Haile Selassie Sidamo vs Ethiopia FTO DP Sidamo Shoye Union Initial Test Roast

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So I obtained some Ethiopia DP Haile Selassie Sidamo from a previous order made by my girlfriend that I wanted to test as a known entity in the new roaster.  We have been drinking Ethiopia DP Haile Selassie Sidamo for the past month or more from a 20# bag order at the end of it’s availability with Sweet Maria’s.  We had a previous sampler sized bag of this and liked it and thus bought a large bag of it.  Unfortunately, while it was good,  it did not taste much like the original that she had had for some time.  It was still good but it was not as good.

The new roaster appears to be very comparable for flavors being developed with the SR500 and the Plus 8 regardless of if you are using a lighter or darker roast changing only the roaster being used.  The older sampler appears to yield fruity flavor while the new one did not.  The new one appears to improve with longer 2-3+ day rest periods.  The only thing I can say with this bean is that the flavors must have changed due to differences in the packaging and how it was stored from the original delivery (which IMO appeared to match the review by Tom exactly) and the final order toward the end of it’s availability that seemed like something entirely different.  In either case it was good coffee but the original seemed better.

Today having done a basic test roast yesterday of the original and letting it rest overnight I have tasted it black, with sugar, and with vanilla creamers.  It seems comparable to what I was getting previously with the Plus 8 roaster.  In preparation for tomorrow’s coffee I have roasted two Ethiopia’s for a “Ethiopia comparison”.

Ethiopia DP Haile Selassie Sidamo


  • 6.0 to 4.0 – Minimal churn.
    • Low Heat
    • 100% Fan
  • 4.0 to 3.0 – @ 4.0 Turning amber to tan range. 3/4 inch expansion. Medium churn.
    • Set High Heat
    • Set 50% Fan
  • 2.8 – Initial First Cracks reached.  Partial brown color. High churn.  2 inch expansion.
  • 2.4 – Rolling First Cracks.  Full brown color.
  • 0.7 – End of First Crack period.
  • 0.2 – Initial sparse 2nd cracks.
  • 0.0 – Automatic switched to Cool.
    • Cool
    • Set 100% Fan

Aroma: Initial aroma strong coffee, spice, woody.  1 hour rest aroma including buttery.
Chaff: Significant

 

Ethiopia FTO DP Sidamo Shoye Union


  • 6.0 to 4.0 – Minimal churn.
    • Low Heat
    • 100% Fan
  • 4.0 to 3.2 – @ 4.0 Turning amber to tan range. 1/2 inch expansion. Medium churn.
    • Set High Heat
    • Set 50% Fan
  • 3.1 – Initial First Cracks reached.  Partial brown color. High churn.  1.75 inch expansion.
  • 2.7 – Rolling First Cracks.  Full brown color.
  • 0.9 – End of First Crack period.
  • 0.3 – Initial sparse 2nd cracks.
  • 0.1 – Forced to Cool.
    • Cool
    • Set 100% Fan

Aroma: Initial aroma virtually non existant.  Some light woody and mild coffee smell.  1 hour rest similar to immediate DP Haile Selassie Sidamo.
Chaff: Significant

Fresh Roast SR500 First Impressions

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So as mentioned in the first blog I received a Fresh Roast SR500 roaster today.  I had been tortured by having coffee roasted in my girlfriend’s Fresh Roast Plus 8 while visiting her and then coming home to coffee out of a can and occasionally the whole bean stuff from the grocery store from my landlord that I rent a room from.  I brought a couple pots worth home after one trip to let me have some good coffee for an extra day or two as well as to introduce it to my landlord.

Like me she instantly saw how good it was compared to the usual stuff and she got interested in the process of roasting at home.  We watched the various videos on YouTube and reviews produced by those at Sweet Maria’s, Coffee Geeks, and a variety of other places.

The Fresh Roast Plus 8 that my girlfriend has and the Fresh Roast SR500 are both somewhat similar machines.  There is also a SR300 which is a less featured version (compared to the SR500) that is also available.  The Plus 8 and the SR300 are technically feature identical since both allow you to set the time only.  All three models have a specified number of minutes and then proceed to a “Cool” period at the end.  The SR500 has the addition of a switch to control the level of heat and a knob to adjust the speed of the fan.

Since I have only viewed an “in-service” Fresh Roast Plus 8 I cannot comment on the original packaging.  The SR500 arrived in a white cardboard box with various marketing type details written on the side.  Inside the box packed in white styrofoam was the SR500 roaster.  This includes a small manual, a small plastic scoop wrapped in a plastic bag, the roaster’s chaff collector, the roasting glass chamber, and the base.

Upon removing all of the parts from the Styrofoam packing I found all of the parts to have small little Styrofoam “dust” / pieces static stuck to the various parts.  As a result I needed to dampen a sponge and wipe off most of the parts or rinse them under a faucet (uhh no rinsing the base please… electric parts and water do not go together)…  Once everything was wiped down I then began to inspect all the various parts.

The Chaff Collector
This part of the roaster is significantly different than the Fresh Roast Plus 8.  I will start describing the Plus 8 and then moving on to the SR500.  The Plus 8’s top is entirely plastic with a screen inside the top part.  The top of the roaster slides down on top of the bottom part overlapping.  The plastic is entirely made from a high temperature plastic so that it does not melt.  It has a feeling of being somewhat light and somewhat inexpensive if not “cheap”.

The SR500 on the other hand also seemed to be a high temperature plastic and cosmetically looks slightly similar to the original Plus 8.  When you pick it up the top of the SR500 appears heavy and somewhat substantial in comparison.  The top is very shallow due to it no longer overlapping the base.  Here it is shown upside down…

The screen appears to be held in by a variety of metallic washers against small plastic “nubs”.

In the center of the lid behind the mesh is a 3 inch (roughly) metallic disc that appears to be similar to the metal used for bolt washers sold in the hardware store.

This provides a lot of bulk that appears to hold the lid on instead of allowing it to blow off.  More on this disc later.  The bottom of the chaff collector cup portion has a similar slotted opening over the roasting chamber to the Plus 8.  There is a sort of angled design to the slots that is different from the original Plus 8.

The top fits to the bottom with a small edge that appears very sensitive to proper alignment as well as proper creation of the plastic pieces when it is injected into the moulds at the manufacturer’s facility. The top piece has a matching groove on the inside to fit.

The top fits over the top of the roasting chamber… but not very well without some effort.  (Notice the gap on the right.  It takes some (minor) effort to get everything to fit snuggly)

The Roasting Chamber
The roasting chamber appears to be maybe 25% wider than the original cup if not more.  I have not measured it but this obviously has to do with the increased capacity of the SR500 from the previous roaster version.  The handle is held on similarly to the original roaster using a metalic band attached to the handle.  The handle on the new roaster is less solid feeling using much less material.  It also gets somewhat warm if not hot to the touch after a full roast.   In addition the metallic base is made from much thinner material… the same as the band on this roaster.

The last base was a thick cast metal base with a glued in round hole screen.  The new roaster has a base that is all one piece pressed from material that appears to be similar to the previous screen.  This results in a less robust feel to the roasting chamber.  I would postulate that this lighter material at the base, however, helps in the cooling cycle by having less metal mass to hold heat near the beans at the end.  Further inspection of this base shows it to be very shallow compared to the last roaster.  The old metal base was much deeper than the current base causing more of the beans to be “hidden” during the initial part of the roast on the old roaster but also allowing the cup to be more firmly seated in the roaster base.

The Roaster Base
Now on to the base…  This is where the most substantial differences are.  The old roaster was perfectly round with a knob that you turned to set the length of time or slide it to cool.  With the new roaster you have a digital “up” and “down” button to increase the time in .1 minute (6 second) increments.

When you start the roaster it starts with 6 minutes immediately dropping to 5.9 on the red LED display.  On the SR500 you start the roaster by sliding the switch to Low, Medium, or the High heat setting.  You raise and lower it by pressing the up and down buttons and can force it to cool by pressing the cool button.  This switches the heat element off into a cool mode running the fan only.  The fan sound is significantly different than the previous Plus 8 roaster.  It is of a different sort of pitch and seems quite loud compared to the Plus 8 though I cannot be sure without running them side by side one after the other. Unlike the SR300 which has only one fan speed the SR500 has a variable knob.  Lowering the fan speed to the middle position on the knob it seems possibly similar to the old roaster.  Due to the much wider base of the roast chamber to accommodate more beans more air is needed to churn the beans.

The wattage on the base is listed as 1600W for 120V.  The model number appears to FB102SR.

Roasting
This roaster seems to thus be more sensitive to being on a solid, level surface.  I have seen several people complain that it does not churn the beans enough resulting in burning.  In the instructions it says to run the beans (if necessary) initially by using the low heat setting with the fan on high.  What I found with an initial roast is that this is an important step until you see significant movement.  With my surface being very level the beans initially had good movement similar to that found in the Fresh Roast Plus 8 and an acceptable churn when set on low heat with high fan.  As the beans began to turn amber in color I then switched the heat to high.  It took approximately 1.5 to 2 minutes for the roaster to reach the amber coloration and the beans to begin to have a more rapid churn.  Once the heat was raised to high I allowed the beans to continue to roast eventually lowering the fan speed to around the half way point until first crack was reached.  At this time I slowly increased the fan until second crack and returned the fan to high during the cool cycle.

One of the drawbacks to the current configuration is you need to purposely remember to return the fan knob to high when you go into the cool cycle.  Otherwise the configuration seems to work well enough as is.  I think this model would be somewhat confusing for a first time roaster for them to figure out what to do and when in response to the roast.  It seems (from other reviews) that the SR500 has a higher fan output than the SR300 at the high setting and my used middle setting being the standard speed on the SR300.  I would consider that to be critical / mandatory making the SR500 the suggested model and thus making this tougher on a new person.  New people should concentrate on running the roaster on high fan and low heat until they see color changes happening as described or a lot of height in the beans being moved.  Once that happens they can dial down the fan speed and increase the heat to get a roast going.

Regarding the smoke from the roaster I have perceived this to be similar to the smoke from a Plus 8 roaster even with the increased capacity.  I didn’t set off the smoke detector but it is pretty obvious you’re roasting coffee inside the house.  You do want to run an exhaust fan while roasting typically with either roaster but it is not significant amounts of smoke.  The roaster does seem to cool down somewhat quickly MOSTLY.

Dealing with the finished roast.
As I mentioned earlier I was coming back to the chaff collector.  Due to the metal disc in the lid of the chaff collector there is a significant amount of heat retained in the lid for a much longer period of time.   This makes dumping out the chaff collector somewhat difficult right away meaning you need to let it cool for a while.  Due to the increased capacity of the roasting chamber you have more chaff collected up top.

The change in the angles of the strainer in the chaff collector do not appear to make much difference in the chaff passing through to the collector.  Most of the chaff appears to stick well into the collector, however, and you end up with similar amounts of fallen bits of chaff on top of the roasted beans that need to be blown out if you do not wish to get any excess in your grind. This roast typically only had a thin ring around the edge in the first picture which is now completely blocked up possibly due to the extra capacity.

The cooled beans are lightly warm and seem to be a few degrees cooler than the Plus 8.  This is possibly due to the cool cycle being digitally timed rather than controlled by a physical timer knob on the Plus 8.  On the Plus 8 the knob does not have any sort of positive confirmation that you are in cooling or heating as you turn it so sometimes you might short the cooling cycle a few seconds while with the SR500 (and 300) you will always have the same cool cycle by pressing the cool button.

At this time I have some beans resting in an airtight container until tomorrow after my initial roast attempts.  These roasts were done “by eye/ear/smell” and later in the week I will dig out my scale and try to get “scientific” about this as I work through the various sample coffees.  For now I just need decent FRESH coffee rather than the swill from a can.

Let there be coffee…

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And God said, “Let the earth put forth vegetation, plants yielding seed, and fruit trees bearing fruit in which is their seed, each according to its kind, upon the earth.” And it was so. The earth brought forth vegetation, plants yielding seed according to their own kinds, and trees bearing fruit in which is their seed, each according to its kind. And God saw that it was good.

That happened on the third day…. probably because by the end of that third day he was getting really tired without some coffee to help him keep working all day and night.  As a result the vegetation came forth allowing a little pick me up from the fruit of the coffea plant with perhaps a little sugar from the sugar cane.  It wasn’t until the 6th day he got to add some cream though.

So on to more serious things starting my experiences coffee roasting.  Today I received via UPS a FreshRoast SR500 from sweetmarias.com in Oakland, CA.  In addition to the roaster I had ordered the 8 pound “regular coffee” sampler.  The samplers can be Regular, Decaf coffee or half-caf.  The full Decaf sampler costs a little more since it does tend to cost more.  You can also opt for an Espresso sampler or just the regular coffee beans depending on your preferred use of green coffee beans.  The beans I received were part of a Regular Coffee sampler.  The random assortment I received were described by Sweet Maria’s as:

  • Honduras Organic – Michelle Guevara Microlot
    • City+ to Full City+
    • Honey-drenched sweet flavor, lemony-bright snap, jasmine tea hints, very pleasant, lively and clean.
  • Java Kajumas Organic Wet Hulled
    • Full City to Full City+
    • This is a low-toned, bass-note flavor profile, foresty flavors, wet earth, humus, dark chocolate, herbal notes, butterscotch sweetness, and low acidity.
  • Ethiopia Fair Trade Organic DP Sidamo Shoye Union
    • City+ to Full City
    • Intense fruit, strawberry, brown sugar sweetness and cinnamon, aromatic wood, sweet caramel finish.
  • Brazil Joao de Campos Yellow Catuai
    • City+ to Full City+
    • Nicely balanced cup with caramel and chocolate roast tones, pungency, spice, and dark chocolate finish.
    • Versatile, great for espresso blends.
  • Sumatra Grade 1 Mandheling
    • Full City to Full City+
    • Very heavy body, complex earthy flavor.
    • This is a deep brooding, pungent, bass note coffee with dark chocolate undertone.
  • Guatemala Bourbon – Finca San Diego Buena Vista
    • City+ to Full City
    • Classic Guatemala cup, balanced between sweet and bittersweet.
    • Vanilla and caramel, citric zest, red apple finish, syrupy mouthfeel.
  • Kenya Nyeria Gathaithi Peaberry
    • City to City+
    • An interesting blend of “Kenya” characteristics:  bright citrus, zesty finish, winey dark fruits, and a touch of sweet Meyer lemon.
  • Rwanda Gkongoro Nyarusiza
    • City+ to Full City
    • A balanced and graceful cup with restrained acidity, sweet citrus, rose, tea-like flavors, floral brightness, medium body, dried orange peel.

Obviously your mileage may vary on what you get when you order.  More to come when I start roasting the beans and brewing.  Next up… observations on the Fresh Roast