Course:FNH200/2014w Team14 Coffee

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Introduction

Coffee beans

For many of us, drinking a cup of coffee is an important ritual in our daily routines. We consume coffee in various ways and in many different situations. Most often coffee is used as a stimulant to keep people alert and awake, as a medium for social interactions, or it can be used in different food and/or drink products to provide a specific flavoring. Coffee is an important aspect in many different cultures and societies and is consumed in various ways around the world, each country providing their own unique twist to the beverage. As coffee culture and consumption is widespread around the world, most people still have no indication of the production process that goes on behind the scenes when purchasing or brewing their favorite cup of coffee. Most coffee drinkers might assume the perfect cup only involves a three step process of coffee grounds, hot water, and the brewing itself; however, there’s more to your average cup of coffee than you might think. Coffee aficionados know there is much more to brewing the perfect cup of coffee which involves many different factors and techniques in order to get the right blend and balance. We will explore the many different processes and aspects of coffee including its growth, production, regulations and industry standards, variations, chemical and physical properties, health risks and benefits, and other interesting facts about your favorite stimulating beverage that you might have never considered.

Production

Growth

Coffee Berry[37]

The production of coffee begins with the coffee tree. A coffee tree is a woody perennial evergreen, covered with dark-green, waxy leaves growing opposite each other in pairs [1]. They have the potential to grow 30 feet high, but in cultivation, coffee trees are kept short for easier harvesting [1]. It takes three or four years after planting for the tree to become productive. The tree produces fragrant white blossoms which, after about a year, the coffee cherries mature. A coffee tree produces continuously: one plant can be flowering, have immature beans and mature cherries all at the same time on the same tree [2].

A coffee tree prefers rich soil and mild temperatures, with lots of rain and shaded sun. It grows best in a band around the middle of the world, this band is simply known as the “Bean Belt” and includes countries like Mexico, Columbia, Brazil, Ethiopia, India, and Vietnam; just to name a few [1][3]. Coffee is grown in only one U.S. state, Hawaii. Hawaii is prized for its Kona coffee beans which is grown on Hawaii's volcanic mountains. The soil where Kona coffee beans grow is a highly desired soil; climate and altitude affect the flavor of the beans making it a desirable bean for both coffee producers and drinkers alike [4].

There is usually one coffee harvest per year. The time varies according to geographic zone, but generally, north of the Equator, harvest takes place between September and March, and south of the equator between April and May [1] Coffee is generally harvested by hand, either by stripping all of the cherries off the branch at one time or by selective picking. Selective picking is more expensive and is typically only used for Arabica beans. Once picked, the coffee cherries must be processed immediately [1].

Packaging and Storage

Packaging

During the process of roasting, a large amount of carbon dioxide is released, which will negatively affect the quality of coffee if the gas is not eliminated.[5] The techniques used to lower the CO2 content in the package are vacuum packaging and special film.[5] The goal of elimination of CO2 can also be achieved by tempering before packaging. Except for degassing, an appropriate package size and materials that prevent products from direct contact with the outside environment are also capable to obtain extended freshness of coffee beans and ground coffee.[6] In addition, an inert gas, usually nitrogen, has to be added into the coffee package in order to obtain a longer shelf life.[6] The common materials used for coffee packaging include polyethylene terephthalate (PET), FOIL, POLY, and MET PET.[7]

Storage

Coffee staling can be caused by both internal and external reasons, such as lipid degradation in coffee beans, roasting, temperature, moisture, and oxygen.[8] The development of stale fragrance of whole coffee beans can take 1-2 weeks, while the ground coffee can undergo this process in only 1-2 days.[9] The coffee beans can even stale faster when exposed to the environment with high temperature, high humidity, and light.[9] After 24 hours’ exposure to room temperature, the shelf life of coffee will be lost by 10%.[5] The best places for coffee storage must be dry, dark, and cool.[10] Fridges and freezers are not suitable for coffee storage because of the high humidity level inside fridges and freezers and the stimulation of degradation of coffee oil.[10]

Varieties

Coffee has two main varieties: Arabica and Robusta. Arabica is descended from the Ethiopian coffee trees. The coffee made from this variety is mild and aromatic [1][3][11]. Arabica beans are the majority of coffee beans grown and accounts for about 70 percent of the world's coffee production [1][11]. These coffee trees grow best in higher altitudes, between 2,000 and 6,000 feet above sea level. The Arabica bean grows best in mild temperatures, 16 to 24 degrees Celsius, and needs about 60 inches of rain per year to ensure sufficient growth [1][11]. Exposure to heavy frost will likely kill the Arabica coffee trees.

Robusta coffee trees represent about 30 percent of the world's market. The bean is smaller and rounder than an Arabica bean. Robusta is a heartier plant and can withstand warmer temperatures, up to 29 degrees Celsius [1][11]. It can also thrive at lower altitudes than Arabica. Robusta beans produce a bitter-tasting coffee with about 50 percent more caffeine than Arabica. Robusta coffee trees are primarily found in Southeast Asia and Brazil.

Typically beans from trees grown in Africa and Arabia have flavor characteristics regarded as "complex, with intense berry or spice undertones." [1][11] Coffee from Latin America is described as "clean-tasting, tangy and bright." Southeast Asian coffees are typically "full-bodied and earthy." However, many coffees are blends of several types of coffee, which produces a more complex flavor.[1][11]

Bean Processing and Roasting

Generally right after picking, the coffee cherries must be processed in order to get it ready for brewing. This is done in either one of two ways:

Dry method

By the simplest and cheapest method, the harvested cherries are spread out to dry in sunlight. They are periodically raked and turned for 7 to 10 days, until their moisture content has fallen to 11 percent. The outer shells of the cherries turn brown and the beans rattle around inside [2][1].

Wet method

The main difference between the wet and dry method is that in the wet method, the pulp of the coffee cherry is removed from the beans within 24 hours of harvesting. A pulping machine washes away the skin and pulp. The beans are put in fermentation tanks for 12 to 48 hours. Natural enzymes loosen the envelope-like layer of the skin covering the beans. The beans are then dried, either by the sun or by mechanical drum dryers [1][2].

Once the beans are dried, the hulling process begins and all of the skin coverings are removed from the beans. Beans are then graded and sorted, first by size, then by density. Beans are either sorted by hand as they pass by on a conveyor belt or by an air jet that separates lighter (inferior) beans from heavier ones [11]. Roasting is where coffee's flavor is most heightened. The green coffee beans are heated in large, rotating drums using temperatures of about 550 F. The tumbling motion of the drums keeps the beans from burning [2][1][11].

Coffee Roasting[38]

The beans first turn a yellowish color and after about 8 minutes, the beans double in size. The beans will have then reached about 400 F and begin to brown as the oils within them start to emerge [1][11].There is a chemical reaction that happens when the beans are heated and this is what produces the essence, flavor and aroma of the coffee. It takes about three to five minutes after the initial 8 minutes before the beans are fully roasted [1][11].

Coffee roasting is something of an art to many people and there is much emphasis and importance placed on timing when it comes to roasting the beans. Those who have mastered the art of roasting use sound, sight and smell to determine when the beans are roasted to perfection. Roasting time affects the color and flavor of the final brew, so the length of the roasting period depends on the type of coffee desired [2].

Regulations, Standards and Quality

Importation Regulations for Coffee

Canadian Regulations

In 2013, new regulations for food importation (including coffee importation) was proposed by the Canadian Food Inspection Agency (CFIA). Under those regulations, a license from CFIA is mandatory for coffee importers, to ensure the safety and legality of their products.[12] Additional requirements include ‘maintain records at an address in Canada; have a written recall plan; and notify the CFIA within 24 hours if they become aware that a product poses a hazard to consumers.’[12] The importation of organic coffee must obey the Organic Product Regulations, or ‘originates from a country with which the Agency has entered into an agreement or an arrangement regarding the importation and exportation of organic products and the product is certified as organic, in accordance with the agreement or the arrangement, by a certification body recognized by that country’.[13]

American Regulations

The commercial imports of coffee are administrated by Food and Drug Administration (FDA).[14] The registration with FDA is mandatory for foreign manufactures and/or distributors.[14] There is no restrictions on the amount of coffee imported, but when coffee is used as an ingredient in other food products, some restrictions may be applied.[14]

Labelling and Grading

According to Consumer Packaging and Labelling Act and regulations, three mandatory statements on a label are product identity (shown in both English and French), product net quantity, and dealer’s name and principal place of business.[15] Different from other foods, except for those mandatory statements, coffee is not required to have a nutrition label because the nutrient content in coffee is very low.[16] Other foods that are exemptions from having a nutrition label include raw meat and poultry, raw seafood, fresh fruits and vegetables, food prepared or processed in store, alcoholic beverages.[16] Based on the colorization of roasted coffee beans, coffee is categorized into several different grading groups including light, medium light, medium, medium dark, dark, and very dark.[17]

Chemical and Physical Properties

Chemical Structure of Caffeine[39]

Coffee beans undergo many physical and chemical changes throughout their processing from harvesting to roasting to brewing. The beans are obtained from the berries of the Coffea plant [3]. These beans have little to no flavour, an herb-like aroma, a green colour and a tough outer exterior [18]. Carbohydrates are the major constituent of coffee beans [19]. The main sugars are sucrose, arabinogalactan, galactomannan and cellulose [19]. The caffeine in coffee beans is an organic molecule produced by the plant as a natural pesticide against herbivores [20], and its’ content within the bean changes minimally throughout processing [18]. An overview of the chemical composition of a green Arabica coffee bean, the bean used in 75-80% of coffee blends [3], is as follows:

Component g/100g
Polyssacharides 49.8
Sucrose 8.0
Reducing Sugars 0.1
Lipids 16.2
Proteins 9.8
Amino Acids 0.5
Organic Acids (Aliphatic, Quinic, Chlorogenic) 8.0
Caffeine 1.2
Water 8-12

Table 1. Chemical Composition of Green Arabica Bean [18]

Low glucose content is an indicator of the quality of the green bean. As sucrose decomposes, glucose is formed and this indicates that the bean is deteriorating [18]. Other quality indicators are the bean size, colour, shape, crop year and presence of defects [18]. Defects include low weight, low water activity, and low acid content [18]. The water activity of a non-defective green coffee bean is about 0.5 to 0.6 at 20°C [19].

During roasting, several important reactions and changes occur that lead to the development of the characteristic flavour, aroma and colour of the coffee bean. At 100°C, the initial change is the evaporation of free water [21]. The moisture loss is about 5% [18]. The aroma changes from herb-like to bread-like, the bean colour becomes yellow, and the structure changes from tough to brittle as dehydration occurs [18]. The temperature is then increased to around 200°C, at which critical reactions occur to produce the desired colour, flavour and aroma [18]. The darkening of the beans is due to the Maillard browning reaction, in which reducing sugars (glucose, fructose, galactose, etc.) react with amino acids and proteins to make brown-coloured pigments called melanoidins [19]. Pyrolitic reactions also take place in which organic material decomposes, releasing carbon dioxide and other volatile compounds, thereby cracking the shell of the bean [18]. This allows the volatile compounds and other oils to escape, which concentrates the contents of the bean and leads to the dark brown colour. Furthermore, degradation of simple and complex sugars, amino acids and organic acids through the caramelization reaction produces slightly sweet caramel notes in the flavour and aroma [18]. Overall, there is a net decrease in sugar, protein and water content of coffee beans during roasting [18]. Caffeine content remains the same [18]. Upon dehydration, roasted coffee beans have a water activity of 0.1-0.3 at 20°C [19].

Although all these reactions occur during roasting, variations in the extent of heat treatment yield different sensorial properties. A low temperature-long time roast is classified as Light roast, and has a light to medium brown colour [22] and a sour, grassy, underdeveloped flavour [18]. Medium roast has a chocolate brown colour [22], a balanced aroma and a citrus flavour [18]. The longest roasting profile is Dark roast, which has a dark brown/black colour, a bold, bitter taste with caramelized notes, and has a less acidic taste than Light and Medium [22]. Excessive roasting can lead to a bitter flavour and an unsatisfactory aroma [18]. Roasting over a short time at high temperature leads to the formation of more aroma compounds and therefore a better brew yield [18].

Finally, coffee as a beverage is prepared by pouring hot water through the ground roasted coffee beans. The colour depends on the level of roast the bean endured and can range from beige to light brown to dark brown to black [3]. The final extract is an oil-in-water emulsion [23] that contains carbohydrates, proteins, lipids, and other organic molecules such as caffeine and acids. Carbohydrates contribute to the binding of aroma compounds, the stabilization of foams in espresso-type drinks, and the higher viscosity (thickening) of the extract [18]. Proteins also help to form foams in espresso beverages by trapping air in bubbles [18]. Lipids, specifically triglycerides, terpenes, tocopherols and sterols, act as stabilizers of the emulsion by increasing the viscosity of the liquid [18]. The carboxylic acids in solution are responsible for the acidity, and make coffee a low acid drink at pH 5.0 [18]. Caffeine content depends on the type of coffee bean used, as well as the mode of preparation [18]. Generally, 207 mL of brewed coffee contains 80-135 mg caffeine, 207 mL of drip (filtered) coffee contains 115-175 mg caffeine, and 45-60 mL of espresso contains 100 mg caffeine [3]. Differences in the conditions used during hot water extraction, such as pressure, temperature, and amount of water, will have an effect on the concentration and other properties of the final extract.

Variations of Coffee

Instant Coffee

Variations of coffee started arising in the early 1900’s and have been steadily inclining ever since. The Japanese produced the first stable “instant coffee product” [24]. Instant coffee gained popularity among American Soldiers during the Second World War when the food and beverage giant Nestlé first introduced their Nescafe brand [24].

Instant Coffee[40]

There are two main ways to produce instant coffee; both involve roasting coffee beans and then brewing them in hot water [24]. The first process (and most common) involves a technique called spray drying:“The coffee is sprayed through a nozzle to produce tiny 300-µm-sized droplets that fall through drying towers until they reach the base as a parched powder. The drying towers are kept at high pressures and temperatures near 270 ºC. The fine coffee powder may be rewetted to produce larger granules that are dried and finally packaged”[24].

The second technique to creating instant coffee is called freeze drying. It involves freezing the brewed coffee, followed by crushing the product to obtain the optimal granule size [24]. Granules that are too small or too large are melted and refrozen [24]. The crushed frozen granules of brewed coffee are then placed in low-pressure drying chambers at -50ºC [24]. As these drying chambers warm up, the water is removed from the granules by sublimation [24]. Sublimation is “the conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage [25].” The freeze drying process can be up to 35% more expensive than spray drying. This is because freeze drying methods require better quality beans as well as larger quantities of them [24].

Both of these methods have to be carefully monitored in order to produce a desirable beverage. If one part of the process is not correct, it could affect the caffeine content or the aromas that are naturally present in the coffee [24]. The final product is packaged using MAP (modified atmosphere packaging), which is the flushing of the product and its packaging with carbon dioxide or nitrogen. This will allow the instant coffee a longer shelf life as well as further losses of aroma and flavour [24].

Decaffeinated Coffee

Another variation of coffee is decaffeinated coffee. The first instance of decaffeinated coffee came in 1903 when Ludwig Roselius accidently discovered his coffee beans were soaked in salt water. Upon drying and brewing these coffee beans, he noticed that they tasted more or less the same but with less of a caffeine hit [26]. In 2015, more than one hundred and ten years later, there are four main ways to decaffeinate coffee. Water is used in all forms of decaffeination since coffee is water-soluble [27].

The first method is called The Indirect-Solvent Based Process. In this process, the coffee beans are soaked in near boiling water for several hours. This allows caffeine to be extracted as well as some other flavour components [27]. The water is then separated into another tank where it is continuously washed with methylene chloride or ethyl acetate for 10 hours [27]. This continuous washing allows the chemical solvent to bond with the molecules of caffeine and the resulting mixture is then heated to evaporate the solvent as well as the caffeine [27]. The beans are then reintroduced to the liquid to reabsorb most of the flavour components that were extracted during the first steps of decaffeination [27].

The second method is called the Direct-Solvent Based Process. This process is similar to the indirect process with a couple of minor adjustments. First off, the coffee beans are steamed for about 30 minutes to allow their pores to open [27]. The beans are then repeatedly rinsed with either methylene chloride or ethyl acetate for 10 hours to remove caffeine [27]. This caffeine-loaded solvent is then drained away and the beans are steamed again to remove any residual solvent [27].

Swiss Water is the third method of decaffeinating coffee. It involves soaking a batch of beans in very hot water to allow the caffeine to dissolve [27]. Next, the water from the batch is passed through a charcoal filter, which captures only larger caffeine molecules and allowing smaller oil and flavour molecules to pass through it [27]. At this point, there are beans with no caffeine and no flavour in one tank, and caffeine free “flavour charged” water in another tank [27]. Proceeding this, the flavourless caffeine free batch is discarded, but the flavour rich water is reused to remove the caffeine from a fresh batch of coffee beans [27]. Since this water is already saturated with flavour, the new batch cannot give up any of its flavour compounds and therefore only gives off caffeine [27]. This last step is imperative to maintain the flavour of the coffee during the decaffeination process. The Swiss Water process is the most effective decaffeination method removing 99.9% of caffeine content [27].

The last decaffeination process is called The C02 Process. Decaffeination happens by placing water soaked coffee beans in a steel container called the extraction vessel [27]. The extractor is then sealed and liquid CO2 is forced into the coffee at pressures of 1,000 pounds per square inch to extract the caffeine [27]. The CO2 acts as a solvent to dissolve and draw the caffeine from the beans, allowing larger molecule flavour components to be left behind [27]. The next step is to move the caffeine filled CO2 into another chamber called the absorption chamber [27]. This chamber allows the pressure to drop and in turn the CO2 returns to its gaseous state and leaves the caffeine behind [27]. The caffeine free CO2 is pumped back into a pressurized chamber and the whole process begins again [27]. This form of decaffeination is primarily used for large quantities of commercial grade, less-exotic coffee [27]. The reason for this is cost [27].

Espresso

A very popular variation of conventional drip coffee is Espresso. Espresso coffee is often blended from several roasts to form a bold flavour [28]. It is concentrated, often thick beverage with a layer of dense foam whose ingredients are exclusively coffee and water. Placing finely ground coffee into a basket, tightly packing it and allowing water to rush through it at high pressure makes espresso [28]. Espresso can be made with any coffee beans and there is no such thing as “espresso beans” [28].

Health Risks and Benefits

Caffeine is very prevalent in the modern world with it being the most consumed psychoactive drug. [29] A lethal dose of caffeine is 10 grams which is the equivalent of one hundred 8-ounce cups, or fifty 8-ounce cups of tea. [29] Risk factors may depend on the gender and situational factors, such as the risk of abortion for pregnant women who consume more than 6 cups per day. [30] Other negative effects include a raise in blood pressure, arterial stiffening and in increase in insulin levels. [29] Even due to some of the negative side effects of caffeine, coffee is still linked to some health benefits due to the presence of antioxidants. [30]

Coffee, consumed with some semblance of moderation, has been linked to several positive health benefits. Masood Sadiq Butt and Tauseef Sultan have highlighted several key health benefits in their review of studies done on the risks and benefits of coffee. Their works indicates that coffee consumption was inversely associated with Parkinsonism, Alzheimer’s disease, diabetes mellitus and several forms of cancer.[30] There is also evidence that suggests that drinking coffee is linked with decreases in liver disease and stroke if consumption is restricted to 3-4 cups a day. [29] However, risk of a myocardial infarction rose when an individual consumed more than 5 cups of caffeinated coffee per day. [31] A recommended dose of two to three cups per day may positively affect cognitive functioning, the sense of sensation and digestion. [30] Furthermore, there does not seem to be any link between caffeinated or decaffeinated coffee and the development of osteoporosis and rheumatoid arthritis. [30] Overall, coffee consumption is connected to health benefits if the consumption is maintained to a moderate level.

Consumption patterns

In Canada, there has been an increase in the consumption of coffee from 1989 to 2009. [32] This pattern is reversed for the consumption of tea, where it had dropped by more than 15%. [32] Statistics from the United States indicates that the average consumption is around three cups per day. [33] This value may differ from other nations since Americans drink the most coffee in the world. [33] While the United States is the largest consumer on a national scale, Finland has the highest consumption per capita. [34] On average, men drink as much coffee as women and the standard cup size is 9 ounces. [33] Specialty coffee sales were raising by 20% per year in 2015, and espresso-based drink only account for 31% of sales. [33] It is also interesting to point out that out of all the regular brewed coffee consumers, only 35% prefer it without the addition of sugar or cream. [33] Globally, the consumption of coffee has doubled since 1972 and it is predicted to exceed 9 million tons by 2019. (6) It is estimated that 1.6 billion cups of coffee are enjoyed each day. [34]

Etymology/Fun Facts

Some interesting facts about coffee:

  • In some cultures, coffee was used in religious ceremonies. It was even banned in 17th century Ottoman Empire for political reasons. Moreover, at one point, it was even linked to rebellious political activities in Europe. [3]
  • During World War II, acorns were used to make coffee. [35]
  • Kraft, Nestle and Douwe Egbers collectively control 70% of the United Kingdom’s coffee market. [34]
  • Men are motivated to use coffee in order to boost performance while women use it as a relaxation aid. [33]
  • Only 50% of America’s population drink specialty coffees. [33]
  • The word ‘coffee’ originally meant wine. [36]

Prezi Presentation

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Possible Exam Question

There are 2 methods of creating instant coffee, spray drying and freeze drying. Based on the lecture readings, which one of these processes is more economically favored?

a. Spray drying is favored over freeze drying

b. Freeze drying is favored over spray drying

c. Both are favored equally

d. Neither are favored since a sun drying is the cheapest


Ans: A. According to the lecture notes, “freeze drying is restricted to high value foods because of the high costs associated with this dehydration method.” This is consistent with our findings, that the freeze drying method is 35% more expensive.


References

Citations

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  13. Government of Canada, Justice Laws Website. 2015. Organic Products Regulations, 2009. http://laws-lois.justice.gc.ca/eng/regulations/SOR-2009-176/page-5.html#h-32 Accessed 2015 March 30.
  14. US Customs & Border Protection. 2014. Importing Tea, Coffee, and Spices for Commercial Purposes. https://help.cbp.gov/app/answers/detail/a_id/337/~/importing-tea,-coffee-and-spices-for-commercial-purposes Accessed 2015 March 30.
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