How does chlorogenic acid break down during baking? What is the relationship between water and chlorogenic acid? will produce

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A brief introduction to the roasting process and the decomposition of chlorogenic acid in Qianjie Coffee

Chlorogenic acid will begin to decompose after water is heated, but during the baking process, water is continuously lost, and the rapid or slow removal of water will affect the flavor production (Mena reaction), but I will only discuss chlorogenic acid here.

Relationship between water and chlorogenic acid

In the case of sufficient moisture (high moisture content of beans, or slow dehydration process before explosion), chlorogenic acid can be fully decomposed into caffeic acid and quinic acid, which is the "hydrolysis" reaction mentioned by Mr. Sweet Mouth on page 94 of Fine Coffee, and there will be sour bitterness (quinic acid) and astringency (caffeic acid) in flavor. After explosion, coffee beans lose all water (here refers to the free flow of water in the green beans), if the beans continue to heat, will force the chemical structure of the molecules dehydration, and quinic acid dehydration reaction to quinic acid lactone, this substance because the original acid characteristic functional group (shuttle) hydroxide combined with another hydrogen to form water, so no longer have acid characteristics, and taste bitter.

Caffeic acid will be removed (to CO2) reaction into ethylene catechol, this substance ethylene structure is the most terrible, if continuous heating can form polyethylene, it will form Taguchi protection described by the "bad bitter" ethylene catechol polymer, you see its phenolic structure, but also a polymer, lead this substance not only bitter, but also astringent, the position should be in the tongue root (bitter) and throat (card).

Under the condition of insufficient water (low water content of beans, or fast dehydration process before explosion), chlorogenic acid cannot be fully decomposed into caffeic acid and quinic acid due to insufficient water content in raw beans (free water is exhausted in advance). At this time, chlorogenic acid will go through "dehydration reaction" to dehydrate part of quinic acid in chlorogenic acid molecule to form chlorogenic acid lactone.