What are the sour beans in the coffee defective beans? Why are there sour beans in coffee beans?

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Physical features:

The appearance color of sour beans is similar to yellowish brown or reddish brown. It is usually black at the endosperm point (the position pointed to by the arrow). When you cut the beans, you can smell the sour smell of acetic acid.

Classification and defect score:

Sour beans are divided into two categories: total sour beans and local sour beans. The difference is similar to that of black beans. If less than half of the beans are locally sour beans, otherwise they are all sour beans.

1 the whole sour bean is a kind of I

Three local sour beans can be regarded as an II defect.

Influence in the cup:

An overfermented sour taste (nausea).

Causes:

The main cause of sour beans is excessive fermentation. If the environment around the coffee is relatively humid, the ripe coffee fruit will be overfermented if it is not picked in time; if the picked coffee fruit is stored for too long and not treated in time, it will also be overfermented; the fermentation pool will be dirty in washing, or dirty with water will also cause sour beans; during drying, if the coffee fruit dries slowly, coupled with improper stacking, it will also cause excessive fermentation of coffee fruit and form sour beans.

Avoid and improve:

Planting: in planting, you can stop harvesting coffee fruits that have fallen on the ground by harvesting ripe fruits (avoiding over-ripe coffee fruits), and do not grow coffee at low latitudes near water sources such as rivers, lakes or reservoirs.

Treatment: timely treatment of the picked coffee fruit to avoid excessive fermentation in storage; soaking time in the fermentation tank should be reasonably controlled; water in the washing process should be changed in time to avoid recycling; the drying process should be reasonably controlled; most sour beans can be removed by hand and color selection.