How to hand-select coffee beans and coffee beans with defects

What is Hand Selection?

Hand selection: It is the step of removing impurities and bad beans attached to delicious coffee beans. Coffee beans are often mixed with foreign objects, such as stones, wood chips, metal pieces, metal pieces, soil particles, tree fruits, etc., and sometimes coins and glass pieces.

In coffee producing areas, gravity bean sorters (which use wind power to sort beans according to particle size and weight) or electronic bean sorters (which remove defective beans based on color) are used to prevent impurities and defective beans from mixing in. However, it is natural that it is difficult to prevent them, and they still have to be sorted by hand.

In particular, unripe beans are 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, shell beans, fermented beans, cracked beans, shelled beans, cocoa beans, etc.

Hand selection is done once at the green bean stage and once after roasting, which means it is done once before and after roasting. The proportion of defective beans is surprisingly high. Good coffee beans generally contain about 20%, and low-refined mocha beans are more than 40%. That is to say, only about 60% to 70% of the coffee beans can be used after roasting. In other words, there will be 30 to 40 grams of failed products in 100 grams of green beans, which is quite a waste. To reduce the roasting failure rate, you must try to buy high-precision high-quality coffee beans; if you are still afraid of roasting failure, you can't be lazy in the step of adjusting the defective beans. Defective beans are the fatal blow to the taste of coffee.

The hand-picking method harvests ripe and red coffee berries, so the rate of defective beans should be much lower. However, in reality, green and unripe berries are also picked during the harvest. Sometimes, in order to pursue harvesting efficiency, even branches are broken. Washed coffee is difficult to be mixed with impurities such as stones and glass because it must be washed many times during the refining process. However, if it is non-washed natural drying method coffee, the degree of impurities mixed is quite high.

If too many defective beans are mixed into the coffee during roasting, the finished coffee will have a mottled color. Compared with normal beans, defective beans oxidize very quickly and sometimes appear white after roasting. Supermarkets and coffee shops often sell cheap coffee beans. If you open the packages, you will find that there are many unevenly roasted beans mixed in. This is the result of skipping the hand-selection step and roasting directly.

The quickest way to understand the importance of the hand-selection step is to cup the coffee extracted from defective beans. After drinking it, you will find that your tongue will remain numb for several hours. This proves that hand-selection is an indispensable and important step in making delicious coffee. People often regard hand-selection as a monotonous, boring, and meaningless behavior and take it lightly, which I think is a pity. But I hope everyone understands that the taste damage caused by defective beans cannot be hidden no matter how advanced the roasting technology is. In order to make the roasting go smoothly, the hand-selection step beforehand is very important.

Next, I will introduce several types of defective beans to you.

Moldy beans: Due to incomplete drying, or moisture during transportation or storage, green or white mold grows, sometimes causing the beans to stick together. If these moldy beans are not removed, a musty smell will be produced.

Dead beans: beans that have not grown normally. The color is not easily changed by roasting, so it is easy to distinguish. The flavor is weak, just as harmful as silverskin, and it will become the source of odor.

Unripe beans: Beans picked before they mature have a fishy, ​​disgusting smell. Leaving the green coffee beans for several years is a strategy to deal with these unripe beans.

Shell beans: Produced by poor drying or abnormal mating; the beans break from the center line and the inside turns out like a shell. Shell beans will cause uneven roasting and are prone to catching fire during deep roasting.

Insect-infested beans: Moths invade and lay eggs when coffee berries are ripe and red. The larvae eat the berries and grow, leaving traces of insects on the surface of the beans. Insect-infested beans can cause the coffee liquid to become turbid and sometimes produce a strange smell.

Black beans: beans that mature earlier and fall to the ground, and ferment and turn black due to long-term contact with the ground. They can be easily removed through the hand selection step. Coffee brewed with black beans will have a corrupt smell and be turbid.

Over-dried beans (cocoa): The natural drying method leaves the pulp and the shell is not fully removed. It has iodine, earthy and other flavors and will smell bad.

Shelled beans: The inner skin covers the inside of the coffee bean pulp, mostly remaining on washed coffee beans. The heat permeability is poor during roasting, and sometimes it will catch fire, which is the reason for the astringency of coffee. Others include cracked beans, red-skinned beans (beans that encounter rain during natural drying, and the taste is bland and monotonous), stunted beans (small beans that stop growing due to lack of nutrients, and the taste is strong), etc. Sometimes corn or peppercorns are mixed in.

Stones: Harvested beans are easily mixed with stones or sawdust due to the natural drying method.

Hand-selected order:

1. Take an appropriate amount of green beans and place them on the tray

2. Select the green beans until there are no defects.

3. Don't just stare at one side of the bean, but pick it up to see its color and shape. Don't miss any one, and move your eyes from right to left.

4. Repeat the same steps over and over again

5. Find out the average value of defective beans picked out.