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Brief introduction of caramelization reaction in roasting of Qianjie Coffee
[caramelization]
The sugar in the coffee bean is caramelized at about 170-200 ℃, which is exactly the melting point of sucrose (185 ℃) and the temperature of the explosion stage when the coffee bean is roasted.
The product of caramelization is divided into two parts:
The dehydration product of sugar is caramel or sauce.
The pyrolysis products are mainly volatile aldehydes and ketones.
Generally speaking, fire-roasted aroma, caramel and color are produced in the caramelization reaction, as well as other aromatic substances such as maltol, Cyclotene, furan and so on. These compounds can also be found in red wine, fruit juices, cream and other foods.
However, if caramel is too much in the baking process is not a good thing, but will cause carbonization, making the coffee dry and choking. If the caramel is not enough, it will make the aroma monotonous and lack of layers.
Volatile and non-volatile compounds
We may have heard of the presence of volatile and non-volatile compounds in cooked coffee beans. In general, volatile compounds are the source of coffee flavor, while some non-volatile compounds are the source of coffee flavor. But what exactly are they?
Volatile compounds are organic chemicals with high vapor pressure at room temperature. Many of them are formed in the Stryker degradation reaction during the development of baking, and we feel the unique smell of coffee when the volatile compounds that produce the aroma emit. These include:
Aldehydes: increase the aroma of fruit and green plants.
Furan compounds: contribute to caramel flavor
Pyrazine: has the smell of dirt.
Sulfur compounds, including 2-furfuryl mercaptan. Some of them have aromas that are often described as "coffee beans", but others are isolated and cannot be smelled. For example, methanethiol smells like rotten cabbage.
Phosphorus methoxyphenol: with smoky, pungent tonality.
Carbon dioxide is a volatile compound that does not affect the aroma, but affects the alcohol thickness of coffee.
