What is the taste of coffee? the taste spectrum of coffee is determined by the degree of baking.

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Coffee taste spectrum consists of "smell spectrum" and "taste spectrum". The former directs dry and wet fragrance, while the latter refers to water-soluble taste. The aroma of "odor spectrum" is appreciated by the sense of smell before and after the nose, and the liquefaction taste of "taste spectrum" is captured by the sense of taste. The "smell" and "taste" of coffee often vary with variety, altitude, soil and water, producing area, post-preparation, extraction and roasting degree, but the biggest cause depends on the roasting degree and technology.

The baking degree determines the trend of taste spectrum.

Perfectly roasted coffee beans are rich in more than a thousand compounds, most of which are volatile, so the fan-shaped "smell spectrum" in figure 1 is more complex than the fan-shaped "taste spectrum" in figure 2. The trend of coffee taste spectrum is determined by the degree of roasting, so the author discusses it on the basis of "shallow culture", "medium culture" and "deep cultivation".

"shallow baking": from the middle of the explosion to the end of the explosion, Agtron#75--#66

Most of the aromatics formed by "shallow baking" are low molecular weight compounds, and the aroma and taste are easy to identify, including sour aroma, herbs, cinnamon, nutmeg, grains, nuts and toast, with the lightest mass and the highest volatility. The sour aroma of coffee is the product of "fermentation", while the taste of grain and bread is the smell in the early stage of Mena reaction in the baking process. Both of them construct the main taste spectrum.

"medium roasting" means after the end of the first explosion to before the second explosion, Agtron#65~#55

The aromatics of "medium baking" are mainly medium molecular weight compounds with slightly higher mass and moderate volatility, mainly furan compounds (Furan) and pyridine compounds (pyrazine), and also have the characteristics of rising into the nasal cavity, which is the mid-term product of caramelization and Mena reaction in the baking process. The aroma is dominated by caramel, cream sugar and chocolate. Although medium baking still has sour flavor, nut and toast flavor, it is obviously weaker than "light baking".

"medium-deep roasting" refers to the violent explosion from the first to the middle of the second explosion, Agtron # 54 ~ # 40

"Deep roasting" refers to the second burst tail, Agtron # 40 million # 30

The aromatics of "medium and deep baking" and "deep baking" are high molecular weight compounds with higher mass than the former two, with low volatility and almost no sour aroma. They are the products of dry distillation at the end of baking, mainly mercaptan, resin, tar and phenolic compounds (Note 3), and can be summarized as turpentine, alcohol, tar, choking incense, and the sweet and bitter taste of caramel and caramel.

The top four chemical components with the highest plant content are cellulose, hemicellulose, lignin and phenols. The weapon of polyphenol plants to resist ultraviolet rays is also the source of plant color. Anthocyanins, tannins, catechins and flavonoids all belong to polyphenols. Coffee is rich in phenolic acids, such as chlorogenic acid, caffeic acid and quinic acid, which are polyphenols and phenolic compounds. Although these phenolic acids are strong anti-nutrient products, the degradation products after baking are bitter, which is the biggest source of bitterness of coffee.

Three sources, nine charm

After roasting, raw beans produce a lot of ignorance, mutual promotion and mutual suppression, changing dry, including fruit, caramel, cream, resin, wine, rice and wheat, stew, pepper, pizza and spice. It is difficult to find a main flavor for coffee. Therefore, Ringer divided the sources of coffee aroma into three categories: "fermentation catalysis", "sugar browning reaction" and "dry distillation".

Shallow baking highlights "Flower Rhyme", "Fruit Rhyme" and "Herbal Rhyme" of "fermentation promoting effect".

Medium baking highlights the "nut rhyme", "caramel rhyme" and "chocolate rhyme" of "sugar browning reaction".

Deep baking highlights the "resin rhyme", "spicy rhyme" and "carbon burning rhyme" of "dry distillation".

It can be said that Ringer divides the aroma of "odor spectrum" into three sources and nine flavors, which are classified into the same source, all of which have similar molecular weight and polarity, that is to say, they have similar odor, water solubility and dissolution point. Let's start with the "catalytic effect of fermentation".

To put it simply, a polar molecule refers to the difference in the negative electricity of an atom in a molecule. The greater the difference, the stronger the polarity and the stronger the water solubility. As far as coffee aromatics are concerned, the low molecular weight organic acids with more shallow roasting content and the medium molecular weight caramel and chocolate flavor compounds with more medium baking content have higher polarity and water solubility. However, the high molecular weight caramel, caramel and resin flavor compounds of deep baked beans have lower polarity and water solubility, so the water solubility of middle baked flavor molecules is higher than that of deep baked beans.

Shallow baking to retain the aroma of flowers and fruits

The "smell spectrum" of shallow baking is mainly dominated by the sour aroma of flowers and fruits in "EnzYmatie" and the ignorance of grains in the early stage of Mena reaction. Because the baking degree is shallow, the organic acids and aldehyde ester aromatic compounds contained in raw beans have the least damage and are easy to show. In addition, the smell of semi-unripe grain in the early stage of Mena reaction is also a common smell of shallow baked beans.

The so-called "fermentation catalysis" in the cup test mainly refers to the low molecular weight and highly volatile aroma of floral acid and herbs such as cinnamon and green beans. There are two mechanisms by which these aromas are produced by "enzyme catalysis".

First, in the process of metabolism of coffee seeds, enzymes are secreted to decompose large units of nutrients such as sugars, proteins and fats into smaller molecules to facilitate seed absorption and germination. When large units of nutrients are broken down into small units of nutrients, malic acid, citric acid and gluconic acid (tartaric acid) will be derived, as well as esters, aldehydes, alcohols and ketones. Among them, esters are more known as fruit flavors, so most of the sour aroma of coffee comes from the fermentation products of the coffee tree itself.

The second source of caffeic acid aroma comes from the fermentation stage of post-processing, the most obvious is that the pectin layer of coffee beans is decomposed into organic acids such as lactic acid and acetic acid by yeast or bacteria during washing fermentation tank, dry body fermentation or sun treatment. increase the sour aroma of coffee. Basically, the shorter the fermentation time, the lower the sour taste, the more likely to show a dull tone, but excessive fermentation will increase the rancidity bad taste.

In addition, after washing or dry body fermentation, the length of the sun-drying process also affects the sour taste of coffee. The longer it takes to dry and dehydrate, the higher the degree of fermentation, the sugar will turn into acid, so the sour taste is heavier. Indonesia Mantenin's unique wet planing method can greatly shorten the drying time and create Mantenin's low sour and smelly "regional flavor".

The cup tester starts measuring the taste at 70 ℃ and does not stop until room temperature, looking for the charming floral and sour aromas described above, as well as testing the coffee for overfermented tarnishes. This kind of sour flavor has the highest concentration from shallow baking to medium baking, that is, from the middle of the first explosion to the second explosion.

Master Ringer summed up the fermentation and promoting effect of "odor spectrum" into three major rhymes: flower rhyme, fruit rhyme and herbal rhyme. The author makes some adjustments as shown in the table below.

Flower charm: flower fragrance and fragrance

Flower fragrance: | Coffee I jasmine I tea rose I lavender I passion fruit

Fragrance: | cinnamon | cardamom | mint | fennel | sandalwood | basil | ginger

Fruit rhyme: citrus and berries

Citrus: | Orange | Lemon | Orange | Apple | Grape | Pineapple

Berries: | Wumei | Blueberry | Strawberry | blackcurrant | Cherry | Apricot

Herbal rhyme: legume vegetables and onions and garlic

Grass fragrance: I forage grass I sugarcane I herb I fairy grass I cucumber I cabbage | pea

Onion and garlic: | Onion | garlic | Leek | durian | celery

The above is the aroma produced by fermentation catalysis, because it is not resistant to heat, it is easy to be decomposed in baking, so shallow baking with lower furnace temperature to medium baking is easy to produce this kind of aroma with low molecular weight and high volatility, but when it enters the deep baking field with higher furnace temperature, these flower and fruit acid aroma will be cracked or converted into other high molecular weight products. As for the aroma of fermentation catalysis, the author simply explains as follows.

The flowers are rare and the oranges are wonderful.

Onion, garlic or green onion in the intact state, the cell wall is damaged, there will be no choking smell, once cut, the cell tissue ruptures, the enzyme immediately combines with the original tasteless precursor aroma, will produce a strong pungent smell.

Incredibly, coffee also has a little onion and garlic flavor, and Master Ringer incorporated it into the attached flavor spectrum of herbal rhyme. Although the concentration of coffee is much lower than that of onion and garlic, I believe that the mechanism of coffee producing this flavor spectrum should be different from that of onion and garlic. It may be that the composition of coffee is too complex. In the process of baking catalysis, occasionally spring onion and garlic flavor will be derived.

No wonder some students often say they smell pizza, seafood sauce, onion and garlic, and beef soup in the process of testing dry and wet fragrance. Almost every experience is different. If there is a strong smell of onions, it is not good. It must be the abnormal smell caused by the deterioration of the protein or fat of the coffee during the fermentation process.

Ethiopia and Yemen sun-dried beans, it is easy to smell a similar durian diluted fruit fermentation or tofu milk flavor, like sweet and a little pungent, is the ancient country of coffee unique "regional flavor", some people love this taste, some people avoid it. In addition, the blue-green boutique washed beans often send out the comprehensive sweet smell of forage grass and sugarcane, all of which are charming herbal fragrance. Mantenin in the East Forest area of Lake dopa, Indonesia, even if baked to medium-deep baking, sometimes can smell fairy grass, which is very interesting.

Shallow roasting is most likely to highlight the volatile fruit acid aroma of ester aldehydes and organic acids stored in coffee beans during their development. In contrast, the smell of too much dirt and mildew of defective beans, as well as the smell of over-fermented rotten fruit, is easy to bake in unmodified shallowness, so it is best not to bake low-end beans so as not to humiliate themselves.

In addition, the grain flavor that often occurs in shallow roasted beans is not the product of "fermentation catalysis", but the process of light roasting to medium roasting of coffee, that is, the taste spectrum from the early to the middle stage of Mena reaction, so it is combined to the "Mena reaction" and "caramelization" under shallow and medium roasting.

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