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Monthly Archives: August 2016

caffein benefit

Caffeine is the most commonly consumed psychoactive drug in the world, and some of its behavioral effects (such as arousal) may resemble those produced by cocaine, amphetamines, and other stimulants. Coffee consumption accounts for about 75% of the adult intake of caffeine in the United States, although that might be changing among younger adults with the growing popularity of energy drinks.

The caffeine content of coffee varies greatly, depending on the beans, how they’re roasted, and other factors, but the average for an 8-ounce cup is about 100 milligrams (mg). Tea has about half as much caffeine as coffee. Decaffeinated coffee has some caffeine, but the 2 to 4 mg in an 8-ounce cup is a smidgen compared with the caffeinated version. The lethal dose of caffeine is about 10 grams, which is equivalent to the amount of caffeine in 100 cups of coffee.

Caffeine gets absorbed in the stomach and small intestine and then distributed throughout the body, including the brain. The amount circulating in the blood peaks 30 to 45 minutes after it’s ingested and only small amounts are around eight to 10 hours later. In between, the amount circulating declines as caffeine gets metabolized in the liver.

Tobacco and marijuana accelerate caffeine metabolism, which reduces the time caffeine circulates in the body. Oral contraceptives slow it down, so they have the opposite effect. Researchers have identified genes that influence a person’s natural risk of caffeine metabolism, which might explain why some people are exquisitely sensitive to caffeine while others are not.

Caffeine probably has multiple targets in the brain, but the main one seems to be adenosine receptors. Adenosine is a brain chemical that dampens brain activity. By hogging adenosine’s receptors, caffeine sets off a chain of events that affects the activity of dopamine, another important brain chemical, and the areas of the brain involved in arousal, pleasure, and thinking. A part of the brain affected by Parkinson’s disease, called the striatum, has many adenosine receptors; by docking on them, caffeine seems to have some protective effects.

Outside the brain, caffeine can be a performance enhancer, boosting the strength of muscle contraction and offsetting some of the physiological and psychological effects of physical exertion. But, especially in the short term, it also has negative effects, which include raising blood pressure, making arteries stiffer, and increasing levels of homocysteine, insulin, and possibly cholesterol. Habitual use may cause some of these effects to wear off. For some conditions, though, coffee may have some benefit despite, rather than because of, caffeine.

A Engineering of Coffee

 The Design of Coffee provides a non-mathematical introduction to chemical engineering, as illustrated by the roasting and brewing of coffee. Hands-on coffee experiments demonstrate key engineering principles, including material balances, chemical kinetics, mass transfer, fluid mechanics, conservation of energy, and colloidal phenomena. The experiments lead to an engineering design competition where contestants strive to make the best tasting coffee using the least amount of energy – a classic engineering optimization problem, but one that is both fun and tasty!

Anybody with access to a sink, electricity, and inexpensive coffee roasting and brewing equipment can do these experiments, either as part of a class or with your friends at home. The Design of Coffee will help you understand how to think like an engineer – and how to make excellent coffee!

This revised second edition presents streamlined lab experiences, adds new bonus material on industrial coffee operations, and includes a new lab experience focused on sensory analysis during traditional cupping of coffee.

* Covers all aspects of making coffee, from green beans to the final brew
* Does not require calculus or college-level chemistry
* Emphasizes the scientific method and introductory data analysis with guided data sheets and lab report questions
* Includes 10 full experiments, each with background on key concepts, overview of necessary equipment, and detailed instructions:

  • Lab 0 – Safety Overview and Introduction to Tasting Coffee
  • Lab 1 – Reverse Engineering a Drip Coffee Brewer
  • Lab 2 – Process Flow Diagram and Mass Balances for Coffee
  • Lab 3 – The pH of Coffee and Chemical Reactions
  • Lab 4 – Measuring the Energy Used to Make Coffee
  • Lab 5 – Mass Transfer and Flux during Brewing
  • Lab 6 – Coffee as a Colloidal Fluid and the Effect of Filtration
  • Lab 7 – First Design Trials: Optimizing Strength & Extraction
  • Lab 8 – Second Design Trials: Scaling Up to 1 Liter of Coffee
  • Lab 9 – Design Competition and Blind Taste Panel

The World Atlas of Coffee: From Beans to Brewing

 Professionals and enthusiasts alike will love this beautiful book by James Hoffmann. From overviews of the world’s most vibrant coffee-growing regions, to step-by-step brewing tutorials, the content is educational, thought-provoking, and substantial. I’ve already recommended this book to Barista Magazine readers countless times.
— Sarah Allen, Editor
Barista Magazine

A beautiful world guide to the brown bean.

Taking the reader on a global tour of coffee-growing countries, The World Atlas of Coffee presents the bean in full-color photographs and concise, informative text. It shows the origins of coffee — where it is grown, the people who grow it; and the cultures in which coffee is a way of life — and the world of consumption — processing, grades, the consumer and the modern culture of coffee.

Plants of the genus Coffea are cultivated in more than 70 countries but primarily in equatorial Latin America, Southeast Asia and Africa. For some countries, including Central African Republic, Colombia, Ethiopia, and Honduras, coffee is the number one export and critical to the economy.

Organized by continent and then further by country or region, The World Atlas of Coffee presents the brew in color spreads packed with information. They include:

  • The history of coffee generally and regionally
  • The role of colonialism (for example, in Burundi under colonial rule of Belgium, coffee production was best described as coercive. Every peasant farmer had to cultivate at least 50 coffee trees near their home.)
  • Map of growing regions and detail maps
  • Charts explaining differences in growing regions within a country
  • Inset boxes (For example, what is the Potato Defect? Is Cuban coffee legal in the United States?)
  • The politics of coffee and the fair trade, organic and shade grown phenomena
  • Beautiful color photographs taken in the field.

Americans consume 400 million cups of coffee per day, equivalent to 146 billion cups of coffee per year, making the United States the leading consumer of coffee in the world. The World Atlas of Coffee is an excellent choice for these coffee lovers.

Coffee Auction in Kenya

 Kenya’s coffee auction system dates back to 1934. The auctions still take place at the Nairobi Coffee Exchange and are widely considered to be most transparent distribution system for fine green coffees anywhere in the coffee world and inspired the model for the Cup of Excellence auctions.

Coffee growing was introduced in Kenya by the British around 1900. In the 1950, several extremely successful hybrids from Scott Laboratories were introduced and these have largely replaced the original French Bourbon stock which had been brought to Kenya from neighbouring Ethiopia. The most well-known are SL28 and SL34 and are Bourbon varieties and lend Kenya the distinctive big body and winy blackcurrant notes for which it is famed.

Following independence from the British in 1963, Kenya organised their coffee industry around a weekly government-run open auction system. This transparent system is establishing a pricing hierarchy based on quality with finer lots fetching higher prices. There is now increasing competition for the better-known estates and co-ops and particularly for the AA grade beans. The grades are simply a measure of bean size, not of defect tolerance. AA is screen 17/18; AB is screen 15/16 with a tolerance for 10% below screen 15.


 Ahead of each auction, samples of each lot are distributed to the 50 or so licensed exporters – or ‘members’ – of the Nairobi Coffee Exchange where they are cupped and sent on also to their customers. In this way, Mercanta receives samples for cupping in our laboratory. We then instruct our exporter on our preferred lots. An agent then bids on behalf of the exporter at the auction to secure the necessary lots.

Since late 2006, some of the restrictions governing the compulsory auction platform have been relaxed. Farmers maintained that the auction system encourages the existence of a long chain of middlemen who eroded the farmers’ income. Supporters of the auction, however, claimed that the auction promoted a price discovery mechanism. The government has licensed 32 independent marketing agents who are now permitted to sell directly to foreign green coffee buyers and bypass the auction system and trade on the open market. Until then, all Kenyan coffee at the auction had been sold through three marketing agents who demanded a fee from the grower for their services. These new licensees were required to fulfill certain criteria before being awarded their license including storage standards, safety and a bank guarantee to ensure farmers are paid.

Today, in 2008, many of the small farmers have yet to find path to the international market though this situation is changing steadily. The auction system, however, continues to run in parallel and is open to all producers.


Finally, we should point out that when buying through the auction system, it can be difficult to gather detailed information on the precise provenance of the coffee. We have visited some of the estates that we know well, such as Gethumbwini, but it is not always possible to achieve complete traceability on all lots. Again, this situation is changing as the market in Kenya – both through the auction and the new licensed marketing agents – adapts to the needs and demands of the specialty coffee roaster and their customers.