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Green Coffee Grading Part II

Robert Barker continues to explore the many facets and intricacies to grading coffee - the last of a two-part series.

Specialty Coffee
The concept of gourmet coffee was established in the 1960 - 70’s with increased popularity in neighborhood coffeehouses. It became fashionable to indulge in espresso beverages and emulate the European lifestyle. Until this time green coffee in the United States was not generally available for purchase in amounts less than a full twenty foot ocean container of 37,500 pounds. Today there are many traders who buy containers of high quality coffee, store it in bonded warehouses and parcel it out in single and multiple bag units to small roasters.

Specialty coffee traders recognize that certain regions consistently produce coffees with unique cup characteristics so in some cases the region becomes part of the grade description. Harrars are very different from Yergacheffes. Antiguas are different from Atitlans. Sumatra, Sulawese and Java coffees have little in common other than all being Arabicas from Indonesia. Often altitude is a critical factor in a coffee’s taste because climate and soil composition make contributions to the cup. In specialty coffee, marketing is highly dependent on the subtleties that define cup character. As with wines, many specialty coffees are marketed under Private Estate names.

The SCAA recognizes two grades, “Specialty” and “Premium”. Grading defects are listed in two categories depending on the severity of impact on the coffee. Certification for Specialty grade allows no defects from category “one” and a maximum of five full defects from category “two”. Premium grade certification is granted with up to eight full defects from both categories. Moisture content, bean size and clean smell of the green coffee are also considered before approval. An illustrated chart is available from the SCAA defining grade. Some defect terms will differ from those used by the Exchange and exporters (see “SCAA Defect Categories” chart on p.26).

Importance of Confirming Grades
The FDA determines the minimum quality for import. After that, the importance of grade depends on whom you ask. Roasters may have a different emphasis than importers. Grade, taste and value are all interconnected in the mind of the roaster. For whole bean sales, appearance is more important. Freshness is also very important because the fresher the green beans the brighter the taste. Without a thorough knowledge of grades and cup quality, a buyer has no common language to discuss quality with suppliers. Demanding quality should be a priority. It’s good for the roaster; it’s good for the industry.

A database of all purchases recording quality, preference, geography and sources gives you a record of importers supplying the highest quality and consistency. It can give you a comparative database of various origins, districts and regions. It assures you that you are getting the premium grade you are paying for.

As more coffee is sold by e-commerce and on-line by auction, it will eventually be necessary to demand grade certification and confirm the grade either in-house or by independent contractor. [www.identrus.com (Identrus) and www.intercommercial.com (InterCommercial Markets Corp.)]

Stock lot coffees from private exporters are often not graded at all even though there may be a grade stenciled on the bag. Many exporters simply rely on the mill to meet the grade requirement and don’t actually check it out.

Undergrade coffee is obviously not traded on the Exchange. These grades may exist only for the convenience of soluble processors. Undergrades are mentioned in the coffee exporter’s guide from the International Trade Center (www.intracen.org) in Geneva, which states that:

“For the United States market, undergrade coffee is any type of coffee that grades below GCA type 6 (120 defects per 370 grams). In mid 2002, United States Customs regulations prohibited the importation of coffee below grade 8 (610 defects per 370 grams) with suggestions from some quarters that this should be raised to grade 7 (240 defects per 370 grams). Other importing markets do not normally specify that particular grades of cof

fee should not be imported, relying instead on general food and hygiene regulations. The ICO is moving to introduce worldwide minimum export standards in an attempt to remove the lowest coffees from the market altogether. The higher risk of mould and therefore OTA occurring in low grades is also likely to reduce demand for such coffees.”

Production Problems
Defects can be caused by biology, contamination, poorly adjusted machinery, poor storage and processing and a myriad of human errors that include the unconscious mixing of cultivars either in the fields or at the middleman level where green coffee is sold by the farmers.

At least half of the world’s coffee comes from smallholders with less than five hectares under cultivation. Many of these are poor farmers without sophistication but years of practical experience. Most are committed to producing the best quality they can yet often they are obliged to farm marginal land without running water.

When world consumption grew, new production moved into more and more marginal lands and lower altitudes; quality could not match that established in perfect conditions. Likewise periods of overproduction and lower prices and lower profits and hence less attention is paid to quality. Lower prices also encourage more overproduction to make up the financial shortfall. The result is an economic spiral: Farmers have less and less capital available to invest in maintenance and improvements. Older trees are stressed and poor producing trees are not replaced with new seedlings.

There are numerous process pitfalls: Over-fermentation is always a particular concern because fermented beans cannot be sorted out, but middlemen buyers at collection centers can identify ferment by smell and reject the coffee. If the collection center buys wet coffee and dries it on site there is a chance that it can be damaged by poorly adjusted mechanical driers or improper patio drying.

Primarily grade is in the hands of nature and husbandry yet it is the mill that will ultimately determine how well a coffee conforms to a grade.

The mill will screen coffee by bean size to comply with the minimum standard of the grade being processed. In fact, the milling process produces all physical conditions of grade.

The mill performance is crucial to the producers, traders and marketers alike. Priorities, schedules and agreements have to be arrived at. In the interest of industrial efficiency, large mills should not be stopped, refitted and restarted without good reason. During peak harvest season they operate around the clock on a specified milling program. A milling committee of producers, and exporters along with the mill owners and operators will meet to arrange the mill and warehouse schedules to achieve optimum results.

It is often the responsibility of the mill to produce a variety of grades and lots. This may entail refitting of screens, adjustments on catadors and densimetric tables and require having the appropriate bags available for filling and having the cargo container at the dock for immediate packing. The committee may schedule runs of a standard grade for exchange coffee, short runs of specialty and premium grades for private exporters and clean up the leftovers as under-grades for internal consumption or soluble coffee producers.

The day-to-day function of the mill is determined by its storage system. It is comprised of a complex battery of interconnected silos that can supply input and collect and store milled coffees. If the mill is processing for individual producers or traders it is obliged to store and process from each supplier separately. At the intake the mill will separate the lots by quality and store each coffee by origin or producer.

On the other hand, if the mill owns the product it is processing it is largely free to decide whether to separate or combine lots to produce a single bulk product or to separate it into a variety of grades. The coffee owner or mill operator will also determine whether over-grade coffee is mixed in or separated.

In either situation quality control is a major concern at any mill because grade is determined by the hands that adjust and maintain machinery that cleans, hulls, screens and sorts the coffee. Quality controls must be initiated before the coffee is accepted for milling, during the milling process and in the determination if and with which other coffee it can be blended.

If an origin has no specific quality standards or grades then it is up to the exporter and importer to determine their own standards and use only mills that can meet the standard.

Ultimately grade is a result of quality controls that have or have not been met from farm to finished product.

Method of Grading
In general, most origin grading systems use the same or similar system of defects used by the FDA and the New York Board of Trade. The percentage of coffee residing on the various screen sizes determines the bean size grade classification and a taste assessment will define the standard of cup quality. In order to assess the quality of a green coffee chop or lot, one is obliged to weigh out the prescribed sample, count defects, screen the sample and actually taste the roasted coffee identifying any off tastes.

The Green Coffee Association of New York specifies 36 cubic inches as a standard sample volume. This will result in a sample weight of 360 to 380 grams. Other jurisdictions use 300 g., 350 g. and 370 g. sample weights. When using the New York standard you can over fill a standard coffee sample tray and scrape it level with the edge of another tray. If you have no standard trays use a cylinder of four inches inside diameter and two and seven eighths inches tall to measure your samples. If you are grading for your own database, it is obvious you would use a consistent sample size by weight or volume. When confirming origin grade use the origin system and appropriate sample size. Some graders use 100-gram samples and multiply the result by 3 or 3.7.

Spread the sample before you. You can use a credit card or similar device to sort through the sample. If you cut off a small triangle from one end of the credit card the pointed end will facilitate your sorting effort. The grading process is facilitated by cutting out small samples of approximately 50 beans per pass, moving them closer to you for examination. Good technique brings consistency to your grading results. You will develop your own style, as you get more familiar with the process. You want to be comfortable and have little or no distraction. If more than one person is contributing to the database it is important to train together in order to minimize differences.

I use a high intensity lamp to illuminate my examination area. Pick out all likely imperfections and deposit them into appropriately labeled glasses, trays or dishes. Paper cups work just as well.

When grading coffee you can use a separate container for each fault but when I have many samples to run I like to use a minimum of glasses by grouping several categories and resorting at the time of counting. I will use one cup for blacks and part black, another for sours and part sours. One for pods, husks, parchments and floats and one for sticks and stones. Even though I’m using the New York standard I will often include a separate receiving glass for the four SCAA defect categories not covered in the NY standard: they being immatures, withered, fungus and insect damaged. I count these defects as 5 = 1 and make note of them in my comments.

After examining the total sample re-examine the contents of each glass and record the results. I like to reweigh the remainder sample to calculate the total weight of defects to arrive at a percentage of defective beans. This will give me a comparison of samples that may have different sample weights. If you care to save the defects for later consideration you can deposit them into small plastic bags sold at bead shops or use paper coin envelops. Two other simple tests that are good for objective results are a density test in which you weigh one liter of beans and record the resultant grams per liter. The second is merely the count of beans in a one hundred gram sample. If you have a moisture meter you can record moisture contents. Of course green coffee grading results can tell only half of the story about a coffee’s quality, only cupping will round out the story and tell you which coffee has merit and the price will tell value.

After 25 years in the coffee business I still have many unanswered questions about grading. Though many of the questions may be inconsequential they are fine points that build confidence when doing your own grading, such as, does a “broken” have to be two thirds of a bean or one half or one third or just a tiny chip? How big a black spot is required for a part black? How many holes designate broca? How many broca defects equal one imperfection. One grader told me that these are not important concerns because grade is ultimately determined by the average results of the three independent graders.

By the way you may find it helpful in the understanding of “cup quality” if you collect enough blacks, sours, floats, immatures and insect damaged beans to do separate sample roasts of these defects to get a taste of their contribution to a clean cup.

Value Regarding Grade
Grading is a basic gauge of value used to assign price to the commodity. A poor showing in defect count can result in a lower price. If such a discounted coffee still has reasonably good cup quality it can be a good value to the right roaster. Roasters of retail coffee that is to be sold as whole beans will obviously be more critical of the defect count in as much as it affects the general appearance of the roasted coffee. Roasters of ground and packaged coffee will give more weight to the actual cup quality and be less critical of the whole bean appearance because it will disappear in the grind. In fact most defects regarding appearance generally have little impact on cup quality yet this is not to say that producers who disregard appearances are paying attention to cup quality. Many producers don’t drink their own coffee much less cup it for quality. If a ragged appearance is acceptable to a producer, why should you think he is concerned with cup quality? This is what makes roasters weary of poor appearances.

In sum, the combined results of defect grade and cup quality assessment will have some bearing on the price of the coffee. This with the condition of suitability of the coffee to a specific market will determine the value of the coffee to the roaster. It is not possible to determine value without grading a coffee and tasting it. It should be self-evident that checking the grade of all purchases and entering them into a database along with comments about cup quality would have enduring benefits to exporters, importers and roasters alike.

Tea & Coffee - May/June, 2004
Theta Ridge Coffee


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