As indicated in the literature, the average consumer drinks 2-4 cups of coffee a day, delivering 2 to 4 mg of caffeine/kg of body weight per day. To prepare a standard serving of coffee in a cup, manufacturers’ data indicates that about 2.5 g of instant coffee is used, which equates to 65 mg of caffeine. For brewing ground coffee, one uses approximately 7-10 g, which corresponds to 120-200 mg of caffeine. An average dose of espresso contains between 40 and 62 mg of caffeine, while a cup of decaffeinated coffee contains up to 4 mg.
Dąbrowska-Molenda and colleagues conducted a study on the caffeine content in selected coffee brews. Brewing coffee in its commercial grain form involved grinding it in a mill just before brewing. Ground coffee, on the other hand, was poured with 150 ml of hot water immediately after boiling. Its brewing time was 5 minutes. Instant coffee brew was also poured with water immediately after boiling, also in the amount of 150 ml. Caffeine was determined using high-performance liquid chromatography (HPLC) using a 2695 Waters liquid chromatograph with a PAD detector.
The highest caffeine content among whole bean coffees was found in Woseba Arabica (2.94 g/100 g of coffee). Among ground coffees, Jacobs Kronӧng had the highest amount (2 g/100 g of coffee). For instant coffees, Tchibo Family had the most caffeine content (1.98 g/100 g of coffee).
The significant discrepancy in the results obtained may be influenced by various factors such as:
- Roasting process,
- Preparation method (grinding),
- Bean variety,
- Brewing method,
- Cultivation conditions.
What is the safe dose of caffeine, and what are the adverse effects resulting from its excessive consumption?
Research has shown that moderate caffeine consumption (up to 400 mg/day) by healthy adults does not contribute to health deterioration, including not affecting the decrease in bone mineral density of those consuming an adequate amount of calcium or increasing the risk of cardiovascular diseases. According to the European Food Safety Authority, a single intake of 200 mg of caffeine is safe for adult health, and its daily dose of up to 400 mg does not result in adverse effects (except for pregnant women, for whom the safe dose should not exceed 200 mg of caffeine/day, due to the risk of impacting the fetus). Prolonged and excessive caffeine consumption of >500-600 mg/day can lead to addiction and can cause a range of negative symptoms, such as anxiety, restlessness, insomnia, arrhythmia, stomach issues, and headaches. Caffeine can adversely influence the health of individuals with mental illnesses by exacerbating symptoms and reducing the effectiveness of medications. A lethal dose is considered to be 5-10 g (about 40-80 cups) of caffeine or 150-200 mg/kg body weight.
Not just caffeine. Coffee composition.
Coffee is not only a source of caffeine but mainly a wealth of biologically active compounds. The chemical composition of coffee beans depends on their origin, soil quality, location of cultivation, cleaning method, cultivation method, and degree of roasting. The most well-known bioactive compound present in coffee is caffeine.
Caffeine is a purine alkaloid with the molecular formula C8H10N402. It belongs to the group of methylamines. It appears as a white powder, odorless, with a bitter taste. Furthermore, it is fully absorbed from the gastrointestinal tract, and then, depending on hydration, distributed to individual tissues. Caffeine does not accumulate in the human body, as it undergoes rapid bioconversion to 1,3-dimethyluric acid, 1-methyluric acid, 1,7-dimethylxanthine, and 7-methylxanthine. Caffeine is excreted in the urine unchanged and as metabolites that are derivatives of xanthine and uric acid. After drinking coffee, caffeine reaches its maximum concentration in the body after about 15-20 minutes. This effect lasts for about 4 hours.
Essential coffee facts
Coffee is one of the most popular drinks in the world. The first coffee plantations appeared in 575 AD on the Somali Peninsula and the Abyssinian Plateau. The word “coffee” comes from the Ethiopian province of Kaffa. Coffee consumption was initiated by the Arabs between the 11th and 12th centuries. The method of roasting raw coffee beans was developed on the Arabian Peninsula, where people learned to make an aromatic coffee brew. It was prepared during the boiling of raw and crushed beans in a mortar. Only later were the beans roasted on heated stones. In our country, coffee appeared several hundred years later, at the end of the 17th century. One of the main reasons for its dissemination was the publication of a book by Rev. Tadeusz Krusiński in 1769 entitled “Description of the proper use of Turkish Coffee”.
World coffee consumption is nearly 9 million tons annually. Its high consumption is particularly associated with its stimulating effect and unique taste. According to data from the International Coffee Organization, in Finland, 11.9 kilograms of coffee per person is consumed annually, making it the highest in global consumption. According to this organization, coffee consumption in Poland is 3.65 kg/year per person. Recently, there has been an increase in coffee consumption in Poland by about 80%.
Types of Coffee
There are primarily 2 coffee species of commercial significance. Among these species, several varieties exist, such as:
- Robusta Coffee (Coffea Canephora) – characterized by a strong and distinct taste. It has twice the caffeine content compared to arabica (2.4-2.8%).
- Arabica Coffee (Coffea Arabica) – is known for its mild taste and a lower caffeine content than robusta (1-1.5%). Due to its low caffeine content, Arabica can only be grown in higher mountainous regions. The harvesting of its fruits (only the ripe ones) is done manually [3,4].
Coffee Brewing Methods
The most popular coffee brewing techniques include:
- French Press – a coffee brewing method using a cafetière,
- Turkish – this method involves boiling cold water together with coffee and added sugar,
- Pressure Machine – water is dosed under specific pressure into a container with coffee, resulting in a highly aromatic coffee,
- Drip Machine – the brew is filtered through a filter into a jug. The brewed coffee contains more caffeine than the one from a pressure machine,
- Dripper – also known as a ceramic filter, is placed directly on a mug, lined with a paper filter, filled with coffee, and then poured over with hot water .
Other coffee brewing methods include:
- Moka Pot – created as an alternative to the espresso machine. Espresso blends are most commonly used. Pre-ground store-bought coffee is not recommended due to the overly fine grind.
- Chemex – a device used for drip brewing coffee. Coffee brewed in Chemex has a distinct taste and higher caffeine content,
- Siphon – considered by many experts as the best coffee brewing method. Brewing takes place by using boiling water, which is then drawn into a chamber by vacuum. This results in appropriate coffee brewing. Coffee brewed using this technique is very aromatic and intense .
The amount of caffeine in coffee depends on many factors. Its content can vary depending on the brand and species, as well as the time and method of beverage preparation. According to the data from the European Food Safety Authority, daily caffeine intake up to 400 mg does not produce adverse effects on the human body.
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Graduate of PWSZ in Konin and WSBiNoZ in Łódź. Enthusiast of a healthy lifestyle and cooking. My motto: "The way to the heart is through the stomach."