Knowledge Encyclopedia | Answers to 25 Frequently Asked Questions for Coffee Newbies

The following are questions that coffee novices often have during the learning process. Now I summarize them for you:

1. What are coffee beans?

Coffee beans are actually the seeds of the coffee fruit (or cherry). During processing, the fruit is partially peeled off and the seed inside is dried to leave the raw coffee beans, which are roasted in a scale from light to dark. The roasted beans are then ground and brewed into the coffee we drink.

The 5 layers of coffee cherries are:

1. Skin/Pulp: The outermost layer of coffee beans is covered with berry-like skin and pulp. Except for the natural sun drying method, coffee beans processed by other methods must have their skin and pulp removed within a few hours after picking. For coffee, skin and pulp are important by-products. In some producing areas, people use coffee skin and pulp to make tea. People in the industry are accustomed to calling coffee skin and pulp "pulp", and the machine used to remove the pulp is called a "pulper".

2. Mucilage: Under the peel and pulp, a layer of sticky mucus tightly wraps the coffee beans. Because this layer of mucilage is extremely sticky and has a very high sugar content, people are used to calling it "honey". Not only coffee, but many fruits also have a layer of mucilage inside.

3. Parchment: Inside the mucous membrane, a thin film of cellulose wraps around the coffee beans. After drying, this film looks like parchment, hence the name.

4. Silver Skin (SilverSkin/Chaff): There is a thinner film inside the parchment paper that wraps the coffee beans. Because of its shiny and silvery color, people usually call it "silver skin". This layer of silver skin will fall off during roasting. Usually when you grind coffee, you will find some silver fragments in the coffee powder. These fragments are the silver skin that failed to be peeled off from the coffee beans during roasting.

5. Coffee beans: Each coffee bean contains two coffee beans (except for Peaberry, which contains only one coffee bean and the other is underdeveloped. Usually, 5% of each batch of coffee beans are Peaberry). After drying and processing, the coffee beans can be roasted.

2. How is coffee classified? I am a novice, how do I choose African beans, American beans, Asian beans and island beans?

The difference between single origin coffee and blended coffee is that one is made from a single type of coffee bean, and the other is made from beans from several different origins. The difference between single origin coffee and espresso is that one is extracted with hot water, and the other is extracted with steam pressure.

According to the variety, it can be divided into Arabica, Robusta and Liberica.

By region, there are African beans, American beans, Asian beans and island beans.

1. Full-bodied coffee: medium-dark roasted beans, such as Mandheling and Honduras.

Mandheling flavor: roasted toast, caramel, cocoa, rich and mellow

Honduran flavors: clean, sweet, nutty, caramel, milk chocolate

Generally, when the roasting degree of coffee beans reaches medium-dark roast or above, small-grain flavor molecules such as fruity acidity and floral and fruity aroma will be transformed into large-grain flavor molecules such as nuts and chocolate through caramelization reaction. When paired with a slightly richer coffee bean powder-water ratio, it is easier to bring out the mellowness.

2. Coffee with high acidity: Lightly roasted washed beans, such as washed Yirgacheffe and Kenyan

Washed Yirgacheffe flavor: jasmine, citric acid, fragrance, black tea

Kenyan flavor: lemon and plum aroma, candied sweet and sour taste, caramel aftertaste

Coffee beans themselves are the seeds of plant fruits, and they have a fruity sour taste. When roasted at a lighter degree, they can retain relatively bright and clear fruit acids, especially washed beans from high altitudes, which have a refreshing and pleasant acidity and often give people a juice-like taste experience.

3. Fruity coffee: Sun-dried + lightly roasted African and Central American beans

Sun-dried Sidamo Oiran flavor: passion fruit, rose flower scent, berry sweetness, black tea aftertaste

Sun-dried Geisha Janssen Estate Flavor: Citrus, apple, pomegranate, ripe grapes, peach, rich sweet and sour taste

Sun-dried coffee beans usually have a richer fruity aroma, especially the sun-dried beans that are finely processed at high altitudes. The fruity tones are complex and charming, retaining enough terroir characteristics at light to medium roasting degrees, and the sweetness is prominent, with a jam-like aroma.

4. If you don't like the astringent taste , try to avoid too high water temperature, don't grind too finely, control the brewing time to about 2 minutes, keep the water flow vertical during brewing, and don't stir too vigorously to avoid the astringency. In addition, remember to pick out defective beans before brewing~

3. What is the difference between Arabica and Robusta flavors?

Arabica coffee smells like grass when it is not roasted. After proper roasting, it shows "fruity aroma" (medium-light roasting) and "caramel sweet aroma" (dark roasting). Generally speaking, it has better aroma and flavor than Robusta beans. This makes it the only coffee among these native species that can be drunk directly and alone, and can be used as a single product or as an Italian blended coffee.

Robusta coffee usually has a rather ordinary, dull, and pungent flavor, and because most of the world's Robusta is grown in low-altitude areas, it lacks personality. Before roasting, it smells like raw peanuts. After roasting, cheap Robusta coffee beans usually have a flavor between "barley tea flavor" (medium-light roasting) and "rubber tire flavor" (dark roasting), which makes it difficult to show delicate flavors.

4. Can roasted coffee beans be eaten?

The short answer is, yes. The longer answer is, yes... but in moderation. Brewed coffee is usually made by grinding beans and then diluting them with water, milk, etc. according to personal taste.

5. What are the differences in coffee roasting degrees?

Coffee beans need to be roasted before brewing. Some coffee purists prefer to buy green beans and roast them themselves, but most people buy a roaster. Although different coffee growers and roasters have their own descriptions of each level of roast, in general, different roasts have the following characteristics:

Lightly roasted beans have low acidity, are slightly bitter, have a milder flavor, and are less full-bodied. They also contain the highest levels of caffeine.

Medium roasted beans are more flavorful, with notes of floral, berry, or earthy flavors, and this is the most common roast for American coffee.

Dark roasting has a strong bitterness and acidity. It is worth noting that dark roasting does not necessarily mean strong coffee, but depends on how it is brewed.

6. The fresher the coffee beans, the better?

Generally speaking, we still think that the fresher the coffee beans are, the better, because roasted coffee beans contain many volatile aromatic substances. The longer they are stored, the more these aromas evaporate. This is an irreversible reaction that cannot be completely prevented.

However, it does not mean that the coffee beans are best brewed right after they are roasted. Coffee should not be too fresh either.

Most coffees require some time (2-3 days) to complete the exhaust process, expelling the gas that enters the coffee beans during the roasting process. We call this process "bean cultivation."

Only after the "bean cultivation" process is completed, the coffee beans will reach their peak state with the fullest aroma and flavor.

7. What is soybean cultivation?

Freshly roasted coffee beans will emit carbon dioxide, causing the pressure in the package to be higher than one atmosphere. The pressure helps the aromatic substances and oils to blend, allowing all the aromatic substances inside the coffee beans to be easily extracted.

The one-way air valve commonly found on coffee bean bags is used to expel excess carbon dioxide and prevent the bean bag from being burst by carbon dioxide.

A few days into the roasting cycle, the so-called outgassing process begins, where carbon dioxide begins to escape from the coffee beans.

How to grow beans: Keep unopened coffee beans in a cool, dry, dark, and odor-free environment. After the bean growing period, seal the one-way valve (use transparent tape).

Italian blend beans: 7-14 days

Single origin coffee beans: 3-4 days

8. Does espresso have a higher caffeine content?

The rich flavor of espresso can easily lead people to mistakenly believe that it has a high caffeine content, but this is not necessarily the case.

Generally speaking, lightly roasted coffee beans and coffee that is extracted for a long time will have a higher caffeine content. Therefore, using the "drip method" to brew coffee, the extraction time is relatively long, and the caffeine content is higher than that of Italian coffee extracted with high pressure and short time.

If we look at the caffeine labels of various coffee drinks listed by Starbucks, a cappuccino with a shot of espresso contains about 75 mg of caffeine, while a medium cup of Americano contains 150 mg of caffeine, which is twice that of Italian coffee. As for the drink with the highest caffeine content, it is this week's coffee brewed using the drip method, which has about 240 mg of caffeine in a medium cup.

9. People who experience palpitations when drinking coffee should avoid coffee altogether

First determine whether you have any problems such as arrhythmia, cardiovascular disease, gastrointestinal disease, etc., and follow the doctor's instructions before deciding whether you can drink coffee.

If a healthy person experiences palpitations after drinking coffee, it may be that the coffee he drank was made from low-quality coffee beans with too high a caffeine content. It is recommended that you try changing the coffee beans or avoid drinking coffee brewed using the drip method.

10. Is drinking black coffee harmful to your stomach?

Although most coffee experts believe that drinking black coffee is the best way to appreciate the beauty of coffee, and therefore do not recommend adding sugar or milk to cover up the original flavor of coffee, some people believe that drinking black coffee can easily damage the stomach.

Some people feel gastrointestinal discomfort after drinking coffee, which is mainly due to the influence of caffeine. For example, caffeine stimulates the sphincter at the lower end of the esophagus, making it more relaxed, which in turn causes " gastroesophageal reflux", or caffeine causes a large amount of gastric acid secretion, causing discomfort.

The culprit is caffeine, so it has nothing to do with whether milk is added or not. Some people may experience more severe symptoms after drinking milk. Therefore, people with digestive tract diseases, such as gastric ulcers, duodenal ulcers, or those who produce a lot of stomach acid every time they drink coffee, should avoid coffee!

11. Can drinking coffee cause osteoporosis?

Coffee intake does not increase bone risk, and as early as 1994 , the Journal of the American Medical Association mentioned that drinking enough milk can provide enough calcium to offset the bone problems caused by coffee. Therefore, the key is whether you consume enough calcium or dairy products, not coffee itself!

12. Does coffee have a high oxalic acid content?

Oxalic acid and calcium are both divalent ions, and theoretically they are a 1:1 combination, so if you want to significantly inhibit calcium absorption, you must contain a large amount of oxalic acid. The oxalic acid content of coffee beans is not low, with 200 mg of oxalic acid per 100 grams of raw coffee beans (dry weight).

However, we also need to consider factors such as roasting, brewing, and usage that will affect the oxalic acid content of coffee liquid. In fact, coffee "liquid" itself is not a food rich in oxalic acid. The oxalic acid content of 100 grams of coffee liquid is only 0.9 mg (link), which is only about 2 mg in a large cup of coffee. How can it be combined with the large amount of calcium in milk?

13. Does caffeine in coffee inhibit calcium absorption?

In addition to oxalic acid, caffeine may also affect calcium absorption? But caffeine does not carry any charge, so how can it affect calcium absorption? To understand this question, we must first understand how calcium is absorbed. The human body has two calcium absorption mechanisms:

Low dietary calcium content and low intestinal calcium concentration:

At this time, calcium is absorbed through two channel proteins located on both sides of the intestinal cells. Calcium will first enter the intestinal wall cells from the intestinal cavity. There is a protein in the cells called calcium-binding protein (calbidin), which will bind calcium and help calcium to be absorbed into the body through the channel protein on the other side. Calbidin is regulated by vitamin D. This regulatory mechanism is that vitamin D binds to the vitamin D receptor (VDR) in the cells, further promoting the production of calbidin.

A high calcium diet leads to high intestinal calcium concentrations:

It passes directly through calcium channel proteins and enters the body through intestinal cells in a passive transport manner. This channel protein may also be regulated by vitamin D.

This shows that both absorption mechanisms may be related to vitamin D. Past studies have reported that caffeine can inhibit the expression of vitamin D receptors (VDR), but no studies have been found to show that vitamin D receptors (VDR) in the intestines are also affected by caffeine. Therefore, there is no way to prove that caffeine will reduce intestinal calcium absorption through this mechanism.

However, some scholars believe that drinking just 1-2 spoons of milk a day can ignore the problem of decreased calcium absorption caused by caffeine!

Although the oxalic acid and caffeine in coffee are not enough to affect calcium absorption, studies have found that caffeine does affect the expression of VDR protein in bones, thereby affecting bone calcium deposition. Caffeine also promotes the activity (connection) of osteoclasts, allowing osteoclasts to release bone calcium into blood calcium.

Many studies have found that drinking too much coffee will increase the risk of bone health. For example, a 2006 study showed that people who drank 2-3 cups of coffee a day had a 39% increased risk of osteoporosis. After correcting many factors, scholars found that the increased risk was related to caffeine intake. Does this mean that drinking coffee is a problem?

How many cups of coffee do women need to drink a day to easily cause osteoporosis? A recent study of 3,170 women aged 50 to 84 showed that if more than two units of caffeinated beverages are consumed a day (one unit is equal to one cup of coffee or two cups of tea), the risk of hip fracture increases by 69%. Therefore, it is recommended that women over 50 years old should reduce their caffeine intake. If they really want to drink coffee, they should not drink more than 2 cups a day.

14. Does coffee have to be drunk while it’s hot?

This is a wrong concept for today's coffee. The quality of early coffee beans was not as high as it is now, so usually after cooling down, some flaws in the flavor would be exposed, and then people would think that cold coffee is not good. However, now the quality of coffee is getting better and better, and the requirements are getting stricter. What we should taste is the flavor of coffee when it is hot, warm, and cold.

Good coffee will still have a good flavor when it is cold. On the contrary, if a cup of coffee has a good flavor when it is hot, but becomes sharp and irritating when it is cold, this is a manifestation of flavor defects.

15. Is hand-brewed coffee definitely better than machine-brewed coffee?

This is a common misconception. Of course, we cannot deny that hand brewing can well show the essential flavor and characteristics of coffee. However, if we need a cup of coffee with a rich and full flavor; or if we need coffee to have multiple variations, we must choose machine-brewed espresso (Italian espresso) to get a cup of coffee with a strong flavor. This is the reason why every inch has its own merits.

One important factor that espresso relies on is the professionalism of the barista, and the same is true for hand-brewed coffee; there is no difference between these two coffees brewed in different ways, the only difference is professionalism.

16. Is latte art just a gimmick or trick?

Many people think that whether latte art is beautiful or not is not important at all, and that it is just the icing on the cake and is dispensable. But in fact, latte art still has a considerable impact on the quality of a cup of coffee.

Because, to make a beautiful latte art, you first need a tank of well-whipped milk foam. If the milk foam is delicate and smooth, the coffee tastes good. In addition, latte art also requires us to pay attention to the fusion between coffee and milk foam, which will have a certain impact on the overall flavor of coffee.

Simply put, the same coffee and milk foam, with or without latte art, will still have a slight difference in flavor and taste. Most importantly, latte art can attract consumers' attention and increase their desire to consume. Moreover, a cup of pleasing latte art can also improve the mood of customers and even affect their sensory judgment.

Therefore, as a competent barista, it is still necessary to learn how to make a cup of coffee that looks good and tastes good.

17. When tasting coffee, you should first hold it in your mouth and then drink it?

In fact, the best way to taste coffee is to hold it in your mouth after taking a sip, but not just hold it in your mouth. Instead, use a method similar to gargling to allow the coffee to contact all parts of the mouth before drinking it.

This tasting method, which may not look very beautiful and graceful, not only allows the coffee to contact all the taste buds in the mouth, but also brings in some air, causing the coffee liquid to produce a small amount of atomization. The air flows through the mouth and nasal cavity, allowing the nasal cavity to smell the complete flavor of the coffee. This is the same principle as the cupper must "sip" hard when cupping.

18. What is the best companion to coffee?

Some people are not used to drinking black coffee, so they always add some sugar and then pour a ball of cream on it to neutralize the bitterness of the coffee.

In fact, coffee itself has very low calories, about less than 20 calories, and is almost fat-free. However, after adding creamer and cream balls, not only do they add extra calories and fat, but they also contain "trans fats", a terrible killer that threatens cardiovascular health. Therefore, it is strongly recommended to abandon creamer and cream (fresh milk) balls and add low-fat milk instead, which is healthier.

People who are used to putting sugar in their coffee also have healthier options, such as trehalose, which has relatively low calories, or asking the store to provide you with a sugar substitute with almost no calories.

19. Coffee + dark chocolate = very French?

The Italian-style espresso is strong and powerful, and paired with the extra bitter dark chocolate with a cocoa content of more than 55%, it is simply a pair of tough brothers, full of power and long aftertaste, making it difficult for people to recover for a long time. In Paris, ordering a cup of coffee often comes with a piece of dark chocolate, which is a very Parisian way of tasting.

20. Is black coffee a single origin coffee?

Black coffee refers to coffee without any added sugar or creamer. Yes, single origin is black coffee, but black coffee is not necessarily a single origin. Some blended coffees are also suitable for hand brewing and siphoning, and the coffee produced is also black coffee, but the beans used are not single origin.

21. What is fancy coffee?

Fancy coffee is the cappuccino, latte, mocha that we usually see... It is made from espresso as the base, with milk foam made through steam, and other additives.

Fancy coffee is made with blended beans to make the taste more balanced and rich. Cappuccino and latte are made in different ways and are not two different types of coffee, so don't name fancy coffee as any other type of coffee anymore.

22. What does Fair Trade Certification mean?

"Fair Trade Certified" means that farmers receive fair wages, no forced or child labor is involved in the growing or picking of the beans, the use of pesticides and other harmful chemicals is limited, and the coffee plantations practice sustainable farming methods. Many brands of coffee are certified as Fair Trade, especially specialty brands. The Fair Trade Certification Program is an international program operated by TransFair USA.

23.What is coffee fermentation?

Many people don't like the fermentation of coffee, while some people really like it. But one thing is certain: fermentation.

The word "fermentation" in daily life often reminds people of making flatbreads, fried dough sticks, steamed buns, and dumplings with leavened dough, or of food going sour and moldy. The processing of raw coffee beans involves "fermentation" to a greater or lesser extent. Just like fermentation to wine, coffee fermentation directly affects the flavor and quality of coffee beans.

Fermentation is a chemical reaction. Yeast, bacteria and other microorganisms work together, either in the presence or absence of oxygen, to make or break down simpler substances. Usually, the substances that break down are sugars. As fermentation occurs, these organisms release heat. Different enzymes also catalyze this reaction.

Simply put, fermentation is a natural process that occurs when sugar and water are mixed together. Coffee cherries contain a lot of sugar and water, so fermentation begins the moment they are picked. The fermentation process can improve the quality of coffee, but it can also ruin it. The key is how to make good use of it.

Fermentation is a form of coffee making that has two meanings:

In wet coffee processing, fermentation is the process by which the sticky pulp is removed from the coffee beans with skin or when the coffee beans are placed in a container and the skin is removed by natural enzymes. If water is added to the container it is called wet fermentation, if no water is added it is called dry fermentation.

In sensory evaluation, fermentation is an important descriptor used to assess the range of flavor defects that occur when the sugars in the coffee beans begin to ferment (by microorganisms). Fermentation can range from sweet, synthetic flavors, to rotten fruit flavors, to musty or medicinal flavors.

25. Will roasted coffee beans get moldy?

After roasting, the coffee beans are dehydrated and in a water-free state. Strictly speaking, they will not mold unless they are damp and contain moisture.

25. What is the difference between “yellow honey”, “red honey” and “black honey”?

The three types are distinguished based on the time of sun exposure and the amount of pectin, and the amount of pectin and endocarp determines the time of sun exposure. "Yellow honey" has 25% endocarp, "red honey" 50%, and "black honey" 80%. Therefore, it takes longer to dry from "yellow honey" to "black honey".

The above is only a small part of the novice's questions. If there are any omissions or inappropriateness, please leave a message to supplement the discussion~

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