What is the difference between good and bad coffee beans?

Have you ever wondered why the coffee beans went bad? What are the defects of raw coffee beans? Why do they have such defects? Today, Qianjie Coffee will take a look at the types of defective beans and the reasons for the formation of defective beans.

Coffee processing usually begins on the same day the fruit is harvested to prevent unnecessary fermentation that may change the chemical properties of coffee beans. In addition, coffee seeds are usually graded and classified according to the size, color and shape of coffee beans to reduce the presence of defects and ensure uniform roasting (Batista and Chalfoun,2014 years, Franca et al., 2005 b ~ Illy and Viani,2005 years). The main metabolites in raw coffee beans have been identified as amino acids, carbohydrates, organic acids, fatty acids, chlorogenic acid (CGA) and volatile organic compounds (Farah, 2012). Several metabolites accumulated in raw beans contribute to flavor and aroma after baking. Defective coffee beans have three main types of physical malformations (such as pea berries, withered seeds and shells), seed damage (due to processing or insect damage) or abnormal colors (such as all-black, partially black or bleached seeds).

The five defective beans that have the greatest impact on the taste and aroma of coffee represent:

Over-fermented beans: pungent astringency, sour and bitter taste

Black beans: black beans and some black beans with stinky and astringent aftertaste. These occur as a result of fungal invasion and produce a very defective smell in the cup. In coffee grading, all black beans are the basis for grading all other defects.

Worm-eaten beans: scorched smell, rotten and fermented taste

Moldy beans: the bitter taste of mildew and decay. It is usually a storage corruption problem.

Floating beans: used to be called sailors. Coffee with no bean density floating in the water.