Classification and causes of defective beans in Fine Coffee SCAA

The growing environment of fine coffee beans also has higher requirements. It generally grows at an altitude of 1500 meters or even 2000 meters above sea level, with suitable precipitation, sunshine, temperature and soil conditions. Some world-famous coffee beans also have special geographical conditions, such as the mountain clouds in the Blue Mountains, the free shade provided by the afternoon "flying clouds" in Kona, and the volcanic ash soil in Antigua, which provide conditions for the growth of fine coffee.

Defect Name: All Black Beans

SCAA Level:

All black beans are a first-class defect;

1 obvious black bean =1 complete flaw

Defect Name: Partial Black Bean

SCAA Level:

Local black beans are a secondary defect;

Less than half of 1 bean is black, 3 beans =1 complete defect

Causes:

1)Agriculture: Blackening is the result of excessive fermentation of pigments by microorganisms.

Preventive measures:

1)Agriculture. Black beans can be prevented at harvest time, picking only ripe fruits from trees, and avoiding excessive fermentation during farm processing.

2)Processing. When the coffee bean endocarp is removed, black beans are very obvious. They are usually small and low density, and some can be removed through screens and density classifiers. The most effective way to pick black beans is by hand or color grader.

Defect name: whole sour bean

SCAA Level:

All sour beans are a first-class defect;

A whole sour bean = a perfect flaw

Defect Name: Local sour beans

SCAA Level:

Topical sour beans are a secondary defect;

Less than half of a bean is sour beans, 3 beans =1 complete defect

Causes:

Agriculture and processing. Tart beans are caused by fermentation, which is the result of microbial contamination at multiple points during harvesting and handling. Specific causes include picking overripe fruit, harvesting fallen fruit, water contamination during handling, or excessive fermentation due to wet conditions while the fruit is still attached to the tree.

Preventive measures:

1)Agriculture: only harvest ripe fruit (avoid overripe fruit), do not harvest fallen fruit, do not grow coffee at low altitudes near rivers, lakes or dams to avoid over-fermentation of coffee beans.

2)Treatment: Tart beans can be avoided by ensuring timely removal of pulp (immediately after picking, avoiding delayed storage). Control the fermentation time in the fermentation tank when washing completely. Avoid contamination or recycling water during washing. Drying should be done promptly and continuously. When coffee beans are clear after removing the endocarp, color graders and hand graders remove multiple portions of the beans.

Defect Name: Mildew Bean

SCAA Level:

Grade one flaw.

1 mold bean =1 complete defect

Causes:

Agriculture and processing. Mold beans are commonly infected with Aspergillus and Penicillium fungi, and improper temperature and humidity from picking to storage can make Fusarium infection of coffee beans ubiquitous. It will induce mold growth. If mold spores are present, the fungus will only grow under these conditions.

Preventive measures:

1)Agriculture: Coffee must be grown in a climate suitable for mold growth, and efforts must be made to suppress the production of pathogens from mold sources. This includes harvesting fruits from the ground or from serious insect infestations, as well as coffee beans left in harvest baskets and drying tanks.

2)Treatment: Good processing of fresh fruit and dehulling can prevent coffee infection. The causes of infection include failure to control fermentation due to breakage or breakage of the beans during pulp removal, beans remaining in fermentation tanks, delayed drying, interruption of the drying process, insect infestation, and storage of shelled beans under high humidity and temperature conditions.

3)Agronomy: Pick only ripe fruit (avoid overripe fruit), do not pick fallen fruit, do not grow coffee near rivers, lakes or dams at low altitudes to avoid over-fermentation of coffee beans. Mold is evident in coffee bean dehulling to remove endocarp. At this stage, the color grader removes many parts of the coffee beans with severe mold infection, while the beans with mild mold can only be removed by hand selection.

Defect Name: Foreign Matter

SCAA Level:

Grade one flaw.

1 foreign object =1 complete defect

Causes:

Multiple: Foreign matter can occur in any process.

Preventive measures:

1)Agriculture: None.

2)Handling: Foreign matter can be removed or avoided by:

Pay attention to branches and leaves when picking.

Pay attention to other substances when drying in the sun, such as stones, sawdust, nails, etc.

At the hulling plant, use appropriate equipment, such as stoner, magnet, to remove foreign matter effectively.

Defect Name: Coffee Dried Fruit/Dried Pod

SCAA Level:

Grade one flaw.

1 dried fruit

or dry pod =1 intact defect

Causes:

1)Agriculture: Drought and disease cause fruit to dry on trees and even fall to the ground.

2)Treatment: The presence of coffee nuts or dried pods in water-washed coffee is the result of a failure of the low-end pulp removal process and the primary selection of floating beans (nuts) with water at the receiving station, and a lack of maintenance or adjustment of the equipment. The presence of dried coffee nuts or pods in sun-treated coffee is a result of inappropriate husking and fractionation.

Preventive measures:

1)Agriculture: Avoid harvesting dry fruit from the ground or trees.

2)Treatment: When there are too many dried fruits, the huller cannot effectively remove them. Removing all floating beans at the receiving station, keeping the pulper properly calibrated and maintained will reduce the production of dried fruit. Any dried pods that pass through the de-pulper can be selected and removed during the de-hulling process by a degree grader.

Defect name: Worm-eaten beans

SCAA Level:

Severely moth-eaten beans are grade 1 defects, 3 or more perforations

5 badly moth-eaten beans =1 complete flaw

SCAA Level:

Slightly moth-eaten beans are classified as secondary defects, with fewer than 3 perforations

10 slightly moth-eaten beans =1 complete flaw

Causes:

1)Agriculture: Berry worms are one of the most serious pests in coffee growing. This insect (coffee beetles) pecks holes in coffee berries and trees, digs tunnels in soft seeds and lays eggs. Newborn eggs usually emerge from the other end, creating two holes in a coffee bean. It is unusual to have multiple channels in a bean. The incidence of this disease tends to increase and decrease with altitude.

Preventive measures:

1)Agriculture: The best way to avoid worm-eaten coffee is to observe and eliminate the conditions that pests like to reproduce. Spraying is an option, but its impact is limited and requires integrated pest management techniques (e.g. special design for fungal management)(Beauveria bassiana) and the use of African wasps. Since pests reproduce in seeds, it is necessary to pick up all coffee berries dropped on the ground to eliminate conditions for their propagation. In addition, the flesh of ripe fruit can carry pests and diseases, so a reasonable distance should be maintained between the tree and the complete compost. It is not feasible to distinguish between healthy and moth-eaten fruit at the time of picking, because moth-eaten damage is generally internal and cannot be detected without very careful observation.

2)Treatment: Worm-eaten coffee beans are visible after removing the endocarp when transported to the dehulling plant. At this stage, density classifiers can remove multiple parts of severely worm-eaten beans. If the coffee is severely infected, hand picking should be used. Severe pest infections have a devastating effect on farmers, rendering most harvests unexportable.

Failure during wet grinding

Destruction during dry grinding

Defect Name: Broken Bean, Broken Bean, Broken Bean

SCAA Level:

Level 2 defects: 5 broken beans =1 complete defect

Causes:

1)Handling: Broken, cracked or broken beans usually occur during de-pulping or de-hulling due to machine adjustment errors, excessive friction or excessive pressure applied to the beans.

Preventive measures:

1)Agriculture: Picking and handling only ripe fruit because immature or partially ripe fruit cannot be properly pulped. Unripe fruit cannot be pulped at all.

2)Treatment: Take care to adjust the pulper to avoid excessive pressure or friction on the beans.

At the hulling plant, the huller is adjusted to avoid rubbing of the beans, and a density grader and size grader are used to remove small broken beans or broken beans. Larger beans must be graded with a color grader or by hand.

Defect name: Unripe beans

SCAA Level:

Grade II defect.

5 green beans =1 complete defect

Causes:

1)Agriculture: Unripe beans are formed due to a variety of reasons for not fully growing well, including improper picking of unripe beans and uneven picking at high altitudes due to fully ripe varieties.

Preventive measures:

1)Agriculture: Unripe beans can be avoided by picking only ripe fruits, or early-maturing varieties can be cultivated at mid-high altitudes.

2)Treatment: Unripe beans can be removed during fresh fruit processing and dehulling. When fresh fruit is processed, many immature beans are distinguished by the size of the shell after removing the flesh. During dehulling, many green beans can be removed by density grading, but many color graders cannot remove this defect.

Defect Name: Dead Bean

SCAA Level:

Grade II defect.

5 beans =1 complete defect

Causes:

1)Agriculture: The main cause of dead beans is the lack of water (drought) when coffee beans are growing in fruit. This damage depends on density and duration of drought. If the coffee plant is fragile or unhealthy, the chances of damage to the beans are very high.

Preventive measures:

1)Agriculture: Keep coffee trees properly nourished and growing healthily to reduce damage. However, climate disturbances such as El Niño can have devastating effects on crops. During dry periods, too many or the wrong shade trees compete with coffee trees for moisture in the soil.

2)Treatment: Heavy dead beans have a lower density and float on the water surface. It can be removed during early water cleaning. During dehulling, dead beans of small size and low density are removed in a density classifier. The larger, thicker dead beans need to be picked out by hand.

Defect Name: Floating Bean

SCAA Level:

Grade II defect.

5 floating beans =1 complete defect

Causes:

1)Handling: This defect is due to improper storage and drying. Discolored, low-density beans are usually produced by shelled beans left in the corners of the dryer or on the sun. Shelled beans can also produce floating beans when stored in high humidity conditions.

Preventive measures:

1)Agriculture: None.

2)Processing: Shelled beans must be dried evenly to a very suitable moisture content. During the dehulling process, some of the low density floating beans can be removed by density graders, but some of the high density ones need to be sorted out by color graders and hand grading.

Defect Name: Shell Bean

SCAA Level:

Grade II defect.

5 shell beans =1 complete flaw

Causes:

Agriculture: This is a natural phenomenon due to genetics.

Preventive measures:

1)Agriculture: Selecting the right coffee varieties and optimizing the growing conditions.

2)Treatment: Shell beans can be removed by density grading during dehulling processing.

Defect Name: Bean with shell

SCAA Level:

Grade II defect.

5 shelled beans =1 complete flaw

Causes:

Handling: This defect occurs during the hulling process and is caused by improper alignment of the huller.

Preventive measures:

1)Agriculture: None

2)Handling: Keep the huller properly calibrated and maintained during the hulling process. The shelled beans can be removed by a density classifier.

Defect Name: Shell/Peel

SCAA Level:

Grade II defect.

5 shells =1 complete defect

Causes:

1)Treatment: The husks or rind usually appear in sun-treated coffee without proper cleaning. Low-end pulper calibrations produce fresh fruit peel fragments that eventually dry into dried fruit shells.

Preventive measures:

1)Agriculture: None.

2)Treatment:

Fresh fruit processing: correct calibration and adjustment of the pulper;

Shelling processing: pay attention to the exhaust (winnowing) process. Pay attention to calibration and adjustment of density classifier.