What are the types of defective beans? Ten factors to consider when selecting coffee beans

If you want to buy good beans, first you have to understand what defective beans are and what types of defective beans there are?

What are defective beans?

If you throw the green beans into the roasting without screening, you will not be able to make delicious coffee no matter how good the technology is. This is because the green coffee beans are often mixed with impurities and bad beans, and we call bad beans "defective beans".

What are the types of defective beans?

Full Black

Characteristics: The whole or part of the green bean is black and opaque.

Causes: Blackening is caused by excessive fermentation, such as fermentation or foul odor, dusty smell, moldy and sour smell.

Full Sour. Partial Sour

Characteristics: Beans are considered tamarind if they are yellow-brown or reddish-brown in color.

Cause: Acid beans are contaminated by bacteria during the harvest and processing process.

Fungus Damage

Characteristics: In the early stage, moldy beans have yellow-brown to reddish-brown spots, indicating that they are attacked by fungal spores.

Cause: Mildew-damaged beans are usually caused by mold spores on the beans. After harvest, they are stored at a certain temperature and humidity that will allow the mold to grow and infect the beans.

Insect damage

Features: Small black holes with a diameter of 0.3-1.smm, usually on the inside of the coffee bean.

Cause: Insect pests are the most serious in coffee farming. The insects drill into the fruits and reproduce when the fruits are still on the tree.

Broken bean

Characteristics: Cracked beans usually have a dark red area due to oxidation.

Causes: Cracked beans are usually caused by improper calibration of the machine and excessive friction or squeezing during pulp or dry processing, which causes the beans to crack.

Immature bean

Characteristics: Unripe beans can be identified by pale and yellow-green skin or white spots on the skin.

Causes: Failure to fully mature has many causes, including improper harvesting of unripe fruit and berries that do not ripen in time late in the season at higher altitudes.

Deformity beans

Characteristics: Abnormal shape, slightly enlarged off-center incision.

Causes: Growth defects, physiological factors.

Shell

Features: Shell beans are separated and deformed from the inside or outside at the same time.

Cause: Mainly due to genetic mutation.

Floater

Characteristics: Floating beans are particularly white or faded in appearance, while green beans have spots in appearance.

Cause: For processing purposes, this defect is caused by improper storage or drying, which usually results in discoloration or lower density of beans.

After seeing the various defective beans above, you should know how important the bean picking process is if you want to have a good cup of coffee. So how should you choose defective coffee beans?

The order of selecting defective coffee beans is "color -> luster -> shape"

When selecting green coffee beans, the best ones are those with uniform shape, thickness, size, color, and the extension of the center line. Unripe beans are especially difficult to remove by machine and must be removed by hand. Moreover, these unripe beans will have a very negative impact on the taste of coffee. In addition to unripe beans, defective beans also include dead beans, worm-eaten beans, black beans, moldy beans, shelled beans, fermented beans, cracked beans, and shelled beans.

• Beans of different colors. Find out what the basis for color selection is, and then put coffee beans of the same color together.

• Beans with different luster. You can select coffee beans according to their luster and remove dead beans and unripe beans.

• Beans of different shapes, such as shell beans, have a minor effect on the taste, so they are processed last.

After you are familiar with the hand-selection sequence 1 to 3, you will be able to make an overall judgment. In this way, the speed of selecting defective beans can be improved, and you will not feel tired after working for a long time. The most important thing is to use both hands. People who are used to using their hands will be faster in selecting, but they will also get tired easily and cannot support the long-term selection of defective beans, so it is recommended to use both hands to select.

Here are 10 factors to consider when choosing green coffee beans:

1. The size of the green beans should be very similar. The appearance must be as consistent as possible, and the color should also be close. This item determines the uniformity of color after roasting, as well as the difference in taste after roasting. For example: 17/18 together, 15/16 together, 13/14 together, etc., because smaller beans and larger beans are roasted at the same time, uneven roasting will be obtained, and therefore, the performance in the cup is also uneven taste. Uneven color of green beans is attributed to problems with the drying process, while uneven appearance may be caused by mixing beans of different tree species.

2. It is necessary to make sure that coffee farmers and processing plants divide the coffee trees into batches based on their geographical growing areas and tree species. These batches must be harvested and processed separately, and cupped separately before deciding whether to mix and store them in proportion.

3. Washed Arabica coffee beans must have a uniform and shiny appearance. There should be no uneven color or dark color. The processing of coffee beans plays a decisive role in the quality of the beans. If the processing is not done properly, the color of the coffee beans will become turbid. Coffee made from coffee beans that look bad will not taste good.

4. Try to understand the details of the drying process of the green beans. If the farm spends a lot of effort on the drying process to ensure that the green beans are properly dried, these efforts will be reflected in the performance in the cup. Improper use of balcony exposure or improper use of dryers can usually be distinguished by appearance: using a dryer to dry quickly will make the green beans look turbid or brown; green beans with spots on the appearance may be because the drying process is too fast, the thickness of the balcony is too thin, or the dryer speed is too slow. Some people suggest that the green beans should be exposed on the balcony for a while to dry the outer skin, then transfer to the dryer, and finally take out and expose on the balcony for the final drying process. They believe that this practice will help to achieve uniform color. Others put the shelled beans into the dryer once every once in a while, and then put them back in the warehouse for storage. In this way, the moisture content of the beans will be more consistent. This step is very important because the moisture content of the outside of the beans must be different from that of the inside. You can first ask the temperature used to dry the beans. If it exceeds 42 degrees Celsius, the product will not be very good.

5. No matter where you buy beans, you need to make sure that the beans are sent to the processing plant immediately after being harvested, otherwise you are likely to get a cup of coffee with a strong fermentation taste, because the coffee beans begin to ferment as soon as they are picked. Ask them how to use the fermentation tank? Are the beans floating on the water picked out? After the demucosation process, are the beans separated into different tanks according to their hardness? Only the manor that spends a lot of time and effort on quality improvement will understand the importance and necessity of these steps. If the demucosation process and the water washing process are carried out in the same tank at the same time, there will usually be some brown color on the surface of the raw beans. The same situation will also happen to the processed over-ripe beans.

6. Dry-processed green beans usually have a brown silver skin on their surface. In Brazil, this is called "Fox Beans" and is not considered a defect. Generally, novice bean pickers will think it is a defect. However, if you rub these beans with a sieve, the silver skin will fall off, so it is not a defect. Unripe beans will also have silver skin on the surface, but rubbing like the former cannot remove the silver skin. Among washed beans, "Fox Beans" have a higher acidity, richer fruity aroma, and sometimes more Rio flavor. As for the direction of the taste, you must rely on drinking to judge, rather than visual observation.

7. Is there pink silver skin covering the gaps or on the surface of the beans? In some areas, this phenomenon is considered a major defect, but most people will ignore this defect for a simple reason, because this item is not listed as a defective bean standard in the coffee bean grading system, so this type of coffee beans may be classified as "Specialty" and enter the hands of buyers. For beans with this situation, it is best to separate them from other beans for cupping to find out whether the degree of defect is very serious.

8. Are the beans white or dark around the edges? This is caused by insufficient drying time or too humid storage environment. The taste in the cup is empty and very dull. Whitening around the beans can also occur in beans that are not dried evenly, which means that one side of the same bean is dried dryer, while the other side may be fine. The causes of whitening beans include oxidation, contact with the ground, or contamination by sewage.

9. Smell the beans. Over-fermentation or smoke contamination can be detected at this time, and these smells may become less noticeable after roasting.

10. Grab a handful of green beans, how do they feel? If they feel brittle, like glass, they may be over-dried or the drying temperature is too high. If they feel too soft, they may not be dried enough. If you receive such beans, you must return them immediately, because green beans with this moisture content are very easy to mold.

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