Green Grading and Cupping Protocol
1) Whenever we receive a green bean sample, whether it is a pre-ship or a landed, we weigh the sample and log it into our inventory sheet in the white lab binder.
2) Fill out lot information in green defect report sheet
3) Measure out 250g and measure moisture level using the Model 920 moisture reader. Note moisture level in defect report sheet.
4) In order to find out the density of the sample, fill the silver tin can up to the brim with green coffee. Then dump out and measure the weight of the contents. Divide the weight obtained by the volume of the can which is 500 ml. Typically coffee will have a density under 0.85 g/cm³. Note density level in defect report sheet.
5) Measure out 300g and green grade, noting defects in defect report sheet.
6) Now sample can be roasted
7) Once roasted, utilize the Colortrak to obtain an Agtron score of the roast level to note in the cup report. Lay out enough coffee in the tray inside the Colortrak reader so that you do not see the bottom of the tray. Select 1-2 on the time selector knob. Open the Colortrak Bench software on the lab laptop and make sure the laptop is plugged in to the Colortrak Reader. Select and Agtron scale on the software and hit start on the Colortrak. You should have a reading within 1-2 minutes, make sure to note it down for the cup report.
Spec sample reports do not necesarily have to have such a level of detail, unless required. In that case many of these steps can be skipped.
Green Coffee Physical Grading for Defects
One of the first tests a sample is subject to is a physical grading. The physical grading of the coffee samples helps to deduce what is the origin of any potential discrepancies found in the flavor or aroma of the coffee. 300 to 350g of the green coffee are weighed out and examined for defects. The SCAA has a standard classification system that is widely used in the physical examination of coffee samples. In this grading system green coffee defects are divided in two categories, primary and secondary. After grading, the green coffee is classified as one of five different categories, depending on the number of defects found:
Specialty Grade Green Coffee (1): Specialty green coffee beans have no more than 5 full defects in 300 grams of coffee. No primary defects are allowed. A maximum of 5% above or below screen size indicated is tolerated. Specialty coffee must possess at least one distinctive attribute in the body, flavor, aroma, or acidity. Must be free of faults and taints. No quakers are permitted. Moisture content is between 9-13%.
Premium Coffee Grade (2): Premium coffee must have no more than 8 full defects in 300 grams. Primary defects are permitted. A maximum of 5% above or below screen size indicated is tolerated. Must possess at least one distinctive attribute in the body, flavor, aroma, or acidity. Must be free of faults and may contain only 3 quakers. Moisture content is between 9-13%.
Exchange Coffee Grade (3): Exchange grade coffee must have no more than 9-23 full defects in 300 grams. It must be 50% by weight above screen size 15 with no more than 5% of screen size below 14. No cup faults are permitted and a maximum of 5 quakers are allowed. Moisture content is between 9-13%.
Below Standard Coffee Grade (4): 24-86 full defects in 300 grams.
Off Grade Coffee (5): More than 86 full defects in 300 grams.
Defects considered as "Primary" are the following:
- Full Black
A bean is considered full black if more than half the bean is opaque and blackened. One full black bean qualifies as a full defect. A full black bean is the result of overfermentation. The effect on the coffee's taste is varied. It can result in a fermented or stinker taste, a dirty, moldy, sour, phenolic taste.
- Full Sour
A bean is considered full sour if more than half the bean presents a yellowish, yellowish/red or yellowish/brown color. One full sour bean qualifies as a full defect. Sour beans result from over-fermentation and the picking of over-ripe cherries, picking of fallen cherries, the use of contaminated water during processing or over-fermentation of the fruit while still in the trees in very humid conditions.If a full sour bean is roasted and ground, it can contaminate as entire pot of coffee with bad flavor.
- Dried Cherry/Pod
- Fungus Damage
You can tell a bean has been damaged by fungus when it presents yellowish or reddish-brown "powdery" spots that have spread across the bean. One fungus-damaged bean qualifies as a full defect. The fungi that commonly attacks coffee beans are from the Aspergillus, Penecillium and Fusarium genus. These fungi attack the beans at any point between harvesting and storage, in places where temperature and humidity levels stimulate the propagation and growth of fungi.
- Severe Insect Damage
Insect damage on a coffee bean qualifies as "severe" if it presents three or more perforations. Five severely damaged beans render one full defect. The most common insect damage is caused by the coffee borer fly, or "broca". They lay their eggs within the fruit and larvae develop inside the bean. Broca perforations can result in a dirty, sour, Rioy(harsh or pungent) or moldy flavors.
- Foreign Matter
Foreign matter is all non-coffee material present in the green coffee. These can be sticks, pebbles or any other litter. The presence of foreign matter comes as a result of improper picking, processing, winnowing and sifting. Every piece of foreign matter constitutes one full defect.
Secondary defects constitute the following defects:
- Partial Black
Partial black beans are caused by the same reasons that cause full black beans and have the same effect on flavor.The only difference is that the bean has been afflicted to a much lesser extent (less than half). Three partial black beans constitute a full defect.
- Partial Sour
Partial sour beans are caused by the same reasons that cause full sour beans and have the same effect on flavor.The only difference is that the bean has been afflicted to a much lesser extent (less than half). Three partial sour beans constitute a full defect.
These beans are partially or fully enclosed in a papery husk that are white or tan in color. Five parchment beans qualify as a full defect.This defect is the result of improper calibration of the hulling machine.
Floater beans tend to have a white and faded appearance. These beans usually float. This defect is usually caused by improper storage or improper drying. Beans that are left in the corners of drying patios can result in a faded, low-density bean that floats. Parchment coffee that is stored in an excessively humid environment can also result in floater beans. Five floater beans equal one full defect.
Immature beans present a yellowish color of the silver skin surrounding the bean. This skin is tightly attached to the bean and the bean is often smaller and curved inwards. These beans have been picked too early and have not been given enough time to mature. They beans can be sorted out in the mill with screens and density sorters. Five immature beans constitute one full defect.
Withered beans tend to be smaller, malformed with wrinkles resembling those of a raisin. A bean withers due to the lack of water during its development within the cherry. When present in high quantities, these beans usually give the cup a weed-like, grassy, straw-like taste. Five withered beans constitute one full defect.
These beans are malformed and have developed as a shell enveloping another smaller conical or cylindrical bean inside of it. These defects are due mostly to genetic reasons. These defects can lead to a burnt or charred flavor due to uneven roasting. Five shells constitute one defect.
A broken, chipped or cut coffee bean usually has a dark reddish color where it was damaged and where oxidation has occurred. In the dry mill broken or chipped beans do not present signs of oxidation because they are not exposed to water. This kind of defect is usually the fault of improper calibration of the pulping equipment. Five broken, chipped or cut beans constitute one full defect.
The hulls/husks of a bean are fragments of the dry pulp that present a dark red color. These show up in lots of beans that have not been properly cleaned. Improper calibration of depulping machines can lead to traces of pulp in the beans. Enough of these present in the sample can lead to a dirty, earthy, moldy or phenolic taste in the cup. Five parchment beans are equal to one full defect.
- Slight Insect Damage
Insect damage on a coffee bean qualifies as "slight" if it presents less than three perforations. Ten slightly-insect-damaged beans qualify as a full defect. The effects on cup quality are very much the same as those for severely insect-damaged beans.
A physical examination, however, is not the absolute test of a coffee. It all comes down to the actual taste and aroma of it during cupping. Physical grading merely serves as a complement to the cupping session to help understand what may affect flavor and smell.
Cupping for Quality
In the trade of specialty coffees, the cupping test is the ultimate test carried out by a potential buyer to determine whether to import a coffee. An experienced cupper is able to determine the vast array of defects that we saw in the previous section through taste and smell.
One must first ensure that the coffee that is going to be sampled receives a proper roast, which would be a light to medium roast. If the coffee is roasted too dark, many of the good and bad flavors that determine a coffee's quality are burned away. The ideal Agtron score for a sample roast should hover around 45. A small amount of coffee should be roasted because if the sample is too big, control and consistency may be lost in the sample roast. Once roasted, the coffee should be left overnight to cool for cupping the following day.
About 12 to 12.5 grams of coffee are to be ground per cup in the cupping table, depending on the size of the cup, as long as the standard brew formula of 8.25g per 125mL of water is used.
Five cups per lot sample are laid out for cupping.
- Stage 1: "Fragrance"
"Fragrance" refers to the olfactory characteristics of the dry coffee grounds. A cupper will bend down and inhale the fragrance of the coffee, noting down its notes and particularities in a cupping sheet.
- Stage 2: "Aroma"
The "aroma" refers to the smell of the coffee while it is in its wet stage. When the water temperature has reached 92ºC-96ºC it is poured into the cups. The cups are then left for 3-4 minutes to allow for the infusion. The cupper will smell the coffee at this point, and record notes. Then the cupper will bring his nose to the top layer of the coffee (known as the "crust") and break it with his cupping spoon. The break releases a lot of important smells. The cupper will then record the notes he detected.
- Stage 3: "Flavor"
The coffee is allowed 3-5 minutes to cool down. During this time the broken crust is removed with spoons to begin flavor testing. When cool, the cupper dips his spoon in the coffee and quickly slurps it up, making sure the coffee touches every part of his tongue. Cuppers may do this multiple times while taking notes. It is important to note that when cupping multiple samples and multiple cups, the cupper must dip his spoon in hot water to remove any trace from the previous cupped sample. Hot water bowls can be laid out throughout the cupping table and filled with the same water used to brew the samples.
Grading the Coffee
After these three tests the coffee is graded based on eleven parameters which are the following, obtained from the November 2009 SCAA Cupping Protocols handbook:
- Fragrance/Aroma - The aromatic aspects include Fragrance (defined as the smell of the ground coffee when still dry) and Aroma (the smell of the coffee when infused with hot water). One can evaluate this at three distinct steps in the cupping process: (1) sniffing the grounds placed into the cup before pouring water onto the coffee; (2) sniffing the aromas released while breaking the crust; and (3) sniffing the aromas released as the coffee steeps. Specific aromas can be noted under “qualities” and the intensity of the dry, break, and wet aroma aspects noted on the 5-point vertical scales. The final score given should reflect the preference of all three aspects of a sample’s Fragrance/Aroma.
- Flavor - Flavor represents the coffee's principal character, the "mid-range" notes, in between the first impressions given by the coffee's first aroma and acidity to its final aftertaste. It is a combined impression of all the gustatory (taste bud) sensations and retro-nasal aromas that go from the mouth to nose. The score given for Flavor should account for the intensity, quality and complexity of its combined taste and aroma, experienced when the coffee is slurped into the mouth vigorously so as to involve the entire palate in the evaluation.
- Aftertaste - Aftertaste is defined as the length of positive flavor (taste and aroma) qualities emanating from the back of the palate and remaining after the coffee is expectorated or swallowed. If the aftertaste were short or unpleasant, a lower score would be given.
- Acidity - Acidity is often described as "brightness" when favorable or “sourness” when unfavorable. At its best, acidity contributes to a coffee's liveliness, sweetness, and fresh fruit character and is almost immediately experienced and evaluated when the coffee is first slurped into the mouth. Acidity that is overly intense or dominating may be unpleasant, however, and excessive acidity may not be appropriate to the flavor profile of the sample. The final score marked on the horizontal tick-mark scale should reflect the panelist’s perceived quality for the Acidity relative to the expected flavor profile based on origin characteristics and/or other factors (degree of roast, intended use, etc.). Coffees expected to be high in Acidity, such as a Kenya coffee, or coffees expected to be low in Acidity, such as a Sumatra coffee, can receive equally high preference scores although their intensity rankings will be quite different.
- Body - The quality of Body is based upon the tactile feeling of the liquid in the mouth, especially as perceived between the tongue and roof of the mouth. Most samples with heavy Body may also receive a high score in terms of quality due to the presence of brew colloids and sucrose. Some samples with lighter Body may also have a pleasant feeling in the mouth, however. Coffees expected to be high in Body, such as a Sumatra coffee, or coffees expected to be low in Body, such as a Mexican coffee, can receive equally high preference scores although their intensity rankings will be quite different.
- Balance - How all the various aspects of Flavor, Aftertaste, Acidity and Body of the sample work together and complement or contrast to each other is Balance. If the sample is lacking in certain aroma or taste attributes or if some attributes are overpowering, the Balance score would be reduced.
- Sweetness - Sweetness refers to a pleasing fullness of flavor as well as any obvious sweetness and its perception is the result of the presence of certain carbohydrates. The opposite of sweetness in this context is sour, astringency or “green” flavors. This quality may not be directly perceived as in sucrose-laden products such as soft drinks, but will affect other flavor attributes. 2 points are awarded for each cup displaying this attribute for a maximum score of 10 points.
- Clean Cup - Clean Cup refers to a lack of interfering negative impressions from first ingestion to final aftertaste, a “transparency” of cup. In evaluating this attribute, notice the total flavor experience from the time of the initial ingestion to final swallowing or expectoration. Any non-coffee like tastes or aromas will disqualify an individual cup. 2 points are awarded for each cup displaying the attribute of Clean Cup.
- Uniformity - Uniformity refers to consistency of flavor of the different cups of the sample tasted. If the cups taste different, the rating of this aspect would not be as high. 2 points are awarded for each cup displaying this attribute, with a maximum of 10 points if all 5 cups are the same.
- Overall - The “overall” scoring aspect is meant to reflect the holistically integrated rating of the sample as perceived by the individual panelist. A sample with many highly pleasant aspects, but not quite “measuring up” would receive a lower rating. A coffee that met expectations as to its character and reflected particular origin flavor qualities would receive a high score. An exemplary example of preferred characteristics not fully reflected in the individual score of the individual attributes might receive an even higher score. This is the step where the panelists make their personal appraisal.
- Defects - Defects are negative or poor flavors that detract from the quality of the coffee. These are classified in 2 ways. A taint is an off-flavor that is noticeable, but not overwhelming, usually found in the aromatic aspects. A “taint” is given a “2” in intensity. A fault is an off-flavor, usually found in the taste aspects, that is either overwhelming or renders the sample unpalatable and is given an intensity rating of “4”. The defect must first be classified (as a taint or a fault), then described (“sour,” “rubbery,” “ferment,” “phenolic” for example) and the description written down. The number of cups in which the defect was found is then noted, and the intensity of the defect is recorded as either a 2 or 4. The defect score is multiplied and subtracted from the total score according to directions on the cupping form.
all the parameters have been assessed, we subtract any defects that may
have been present and get a Final Score. SCAA standards define each
score as the following classification:
|95-100||Super Premium Specialty|
|75-79||Usual Good Quality (UGC)|
What Happens when Quality goes Wrong?
Protocol for Questionable Landed Samples:
If a landed sample, on first roasting and cupping, fails to deliver a passing score, seems contaminated against the pre ship sample, or has general other flaws resulting in a impassable score, the following steps will be taken by the cupping lab at Labo Equitable.
- Sample will be re-roasted and re-cupped. If defect is no longer present, we will assume the flaw was either roast attributed or a random cupping anomaly. Cup Report will be drawn and released stating the coffee has been approved.
- If sample still does NOT meet expectations, three roasts of varying degrees will occur to explore the roast range that the defect is most prevalent. If no defect shows up at all during this step, passing Cup Report will be released with notes indicating sample has been through this stage with notes on potential uses for this coffee.
- If sample STILL does not meet criteria, shipping station will be notified and another sample from the landed bags will be requested. The selling producer organization and Coop Coffees offices and roasters will be notified that the coffee is on hold while we dig deeper into investigating the situation.
- The three steps listed above will be repeated in proper order as necessary until the sample either passes or officially gets rejected. If passing, the Cup Report will be released and uploaded and Coop will be notified of release. If rejected, Coop will be notified with suggestions for moving the container of coffee to different potential outlets - including transferring ownership back to the producer organization.