Coffee Roasting Temperature and Coffee Profiles: The conclusions shown are a study based on Temperature Gradients and shows the correlation bewteen the Heat and the Temperature the Roasting Machine and the Coffee Seed.
The Working Temperature is the one you set for the Roaster – the Machine-. This one must be [140 C to 165 C] (around 300 F).
This criteria fits the Miallard Process and gives always the best process by avoiding acrylamids and extra bitterness.
The only way to measure the ‘Roasting Temperature’ for the Coffee Seeds (GreenBeans) is at the exit of the machine.
That temperature gradient changes within the time and let the coffee seeds to absorb the heat from the external part to the interior of the coffee seeds.
So even the working temperature still remains at 160 C i.e. the coffee seed will increase its temperature value based on the ratio between the Heat Transfer and the time.
The fastest change occurse just after the coffee seed is considered dry (Drying Phase).
The Drying Phase is the amount of time needed for the coffee to be dry so when the water contained in the seed becomes as vapor in the roasting system helping alos to the heat transfer not only by contact, but by convexion too.
The heat transfer to the interior of the Coffee Seed relies on its density.
The density in this case acts as the capacity to resist a change: a Chemical structure change i.e. form Chlorogenic acid to Cafeic Acid.
A grain of high density values is one whose value is greater than 0.68 g / mL. Coffee seed density usually comes from: (0.64 to 0.72) g / mL. The Chlorogenic acid is related to those coffee density values in terms of its presence and The Chlorogenic acid is the most important compund in relation to the aroma, flavour and notes.
The Coffee seed in general has 6% to 7% mass/mass of Chlorogenic acid and based on that mass of The Chlorogenic acid we can tell the correspondant coffee density value: 6% to 0.68 , 6.5% to 0.70 , 7% to 0.72.
The Chlorogenic acid (CGA) is the ester of caffeic acid and (−)-quinic acid, functioning as an intermediate in lignin biosynthesis. The term “chlorogenic acids” refers to a related polyphenol family of esters, including hydroxycinnamic acids (caffeic acid, ferulic acid and p-coumaric acid) with quinic acid. The name “Chloro” comes from the Greek χλωρός (light green) and -γένος (a suffix meaning “giving rise to”), pertaining to the green color produced when chlorogenic acids are oxidized.
About the chemical composition and all the different chemical substances that may exist in the coffee seed there are Coffee Seeds (coffee grains, green beans, beans) that contain in greater proportion the compounds responsible for the aroma and flavor.
The highest concentration of the most desirable compounds depends on different main elements such as: density, the coffee varietal, the soil composition, water and rain, Sun and light conditions, the fermenting process, but mainly all are related to what’s the final value for density.
The elements that interfere more with the density beyond the coffee varietal is the altitud that cause stress in the plant for less presence of oxygen in the air composition. The fermenting process such as non-conventional process (honey: semi-washed, natural: unwashed) creates new falvours and aromas.
The effect of Altitude on the concentration of Coffee Seed compounds?
The Farm Altitude (above the Sea level): The greater the Altitude, the lower is the presence of oxygen in the air. So the plant must resort to its nourishment, to those soil nutrients, including water source, for via photosynthesis create compounds that allow the highest dilution of oxygen and thus avoid dying or malnutrition.
This has an obvious improvement in the final result of the Coffee Seed(coffee bean, GreenBean).
The altitude condition will affect the coffee seed density in certain possible ranges according to varietal, Latitude North or South insde the Tropic of Cancer range, and photosynthesis.
The phtoshyntesis depends on rain or irrigation, and the Sun or light conditions during the year. In combination with the soil preparation, the soil nutrients the Coffee Seed density will have a higher value, but much more if the altitud is higher.
That is the reason to name Coffee as SHB, SHG, and HG in accordance to the Farm/Lot altitude and its own country standard that change the value for SHB depending on its relative distance from the Ecuador line, Latitude.
Example: Costa Rica has its standard for SHB above 1.200 m over the Sea level, if we use the same standard for North Nicaragua Region that makes that an SHB become 1.000 m over the Sea level.
SHB: Stricly Hard Bean
SHG: Stricly High Grade
HG: High Grade
The Maillard process is a chemical reaction that under the presence of a heat source reacts an amino acid with a sugar.
Coffee Roasting Curve of Caturra and Red Catuai, Un-washed process, single origin.
The graph above shows the curve of the change of Temperature versus Time, that is to say the changes of temperature of the coffee during the toasting time. Additionally there is a cooling curve that is the final stage of the pyrolysis in the post-combustion.
The Roaster Temperature is affected by factors heat source and its performance relies on his Heat Distribution.
The Coffee Seed Temperature depends mainly on two elements: Coffee Seed Moisture (Relative humidity) and Coffee Seed Density Value.
1. Coffee Seed Moisture: for Green Beans must be between 10% up to 12%. The Coffee Roasting batch must be all at the same level of humidity. It means the level of each other GreenBean must be the same: homogenic. ywhich affects the performance (weight input / weight output), normally located between 80 to 83%.
2. Coffee Seed Density Value (organic compounds: amount of, types of, and relative presence of), which allows the best resistance to heat and a more even development, which is why, for the best roasted coffee it is only achieved with coffees from first selection, high density.Recommendations: The working range should be between 140 ° C and 165 ° C. The work at high temperatures favors the development of Acrylamide, which influences unpleasant odors of nitrogen oxides. Acrylamide is a dangerous carcinogen.
What is a Roasting Sample ?
A roasting sample is a representative quantity that is specified by the standard referred to, for example it is usually taken between 250 grams and 300 grams, and is usually ordered 1kg or you can also ask for 1 pound which would make an average test pound and a reference reserve of half a pound is left.
The sample of tasting is usually done to determine the quality and valuable properties of the grain and its presentation to analyze. In general, a clear City-type roasting is chosen, which is between 75 and 85 points on the Agtron scale.
The development of the subtle properties and flavors are still present in the light roast, and in the roasts of greater duration in the roasting process (medium and dark) some flavors and elements are lost, but others are intensified in a very specific way, by For example, the greater caramelization of the sugars gives more caramel and chocolaty tones, but it is usually in the same way to decrease the level of acidity of the present sample.
There is another type of analysis of samples which are considered personalized, which are used for a custom criteria to match the characteristics and qualities with their respective cup quality score. For example the evaluation of a coffee roaster under a FULL CITY profile, with a color score in the Agtron scale of 55 to 65 for different grains which are going to be roasted in very similar ways to finish with that requested color and that roasting profile to evaluate if flavor elements such as aroma, or the body develop more or if they decrease and if the balance level at the end of everything is of greater consistency than the others. You can try whatever you want, but these are quality control tastings and they are more used now not in the Benefit but rather in each of the Roasting Industries.