MANUFACTURE
How is a flavoured coffee bean made?
Flavoured coffee beans are coated with flavour compounds to supplement coffee beans' natural taste. In addition, these flavours help extend the shelf life of coffee by disguising changes in flavour due to decaffeination, oxidation, or aging processes. Flavoured coffees in one form or another have been used for centuries, but the gourmet coffee boom of the 1990s resulted in an increased interest in exotic flavours of coffee. With current chemical technology, the beans can be produced with almost any flavour imaginable.
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Although many people regard flavoured coffee as a modern invention, its origins are nearly as old as the original beverage itself. History shows that a few hundred years ago in the Middle East, people enjoyed drinking coffee blended with nuts and spices. In modern times, innovative marketers have capitalized on coffee drinkers' desire for more flavours than nature can provide and have found new ways to introduce flavouring agents into coffee. First, flavoured syrups were used to spike brewed coffee with a touch of a favoured flavour. More recent improvements in food science have led to ways of introducing complex flavours directly onto the beans as part of a post-roasting process. When these flavoured beans are used for brewing, the flavour is extracted into the resulting beverage. Today consumers can choose from a wide array of flavoured coffee beans with names like "Chocolate Swiss Almond", "Hazelnut", "Amaretto Supreme", "Irish Cream", "French Vanilla", and "Georgia Pecan".
Raw Materials
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Coffee beans - The type of bean used to make flavoured coffee greatly impacts the taste of the finished product. It is estimated that coffee beans contain over 800 different compounds which contribute to their flavour, including sugars and other carbohydrates, mineral salts, organic acids, aromatic oils, and methylxanthines, a chemical class which includes caffeine. The bean's flavour is a function of where it was grown and how it was roasted. The name of the beans usually indicate their country of origin, along with additional information, such as the region within the country where the beans were grown, the grade of beans, or the type of roast. For instance, "Sumatra Lintong" denotes a specific growing region (Lintong) in Sumatra; "Kenya AA" designates AA beans, the highest grade of beans from Kenya; and "French Roast" is a blend of beans which are roasted very dark in the "French style". Some flavoured coffees consist of only one kind of bean, like Kenya AA, which has distinctive regional taste characteristics.
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In general Coffea arabica (or arabica) beans are used for flavoured coffees due to their low levels of acidity and bitterness. Arabica was the earliest cultivated species of coffee and is still the most highly prized. These top quality beans are milder and more flavourful than the harsher Coffea canefora (or robusta) beans, which are used in many commercial and instant coffees. Some manufacturers create flavoured coffees from a blend of beans from various regions. High quality beans are grown in Colombia, Mexico, Costa Rica, and Guatemala.
Flavouring Oils​
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Flavouring oils are combinations of natural and synthetic flavour chemicals which are compounded by professional flavour chemists. Natural oils used in flavoured coffees are extracted from a variety of sources, such as vanilla beans, cocoa beans, and various nuts and berries. Cinnamon, clove, and chicory are also used in a variety of coffee flavours. Synthetic flavour agents are chemicals which are manufactured on a commercial basis. For example, a nutty, woody, musty flavour can be produced with 2, 4-Dimethyl-5-acetylthiazole. Similarly, 2,5-Dimethylpyrazine is used to add an earthy, almost peanuty or potato-like flavour. Flavour chemists blend many such oils to achieve specific flavour combinations. While other food flavours may be composed of nine or 10 ingredients, coffee flavours may require up to 80 different compounds to achieve subtle flavours. Virtually any taste can be reproduced. Marketers have found that consumers prefer coffee flavours with sweet creamy notes. The ideal flavour should mask some of the harsh notes of the coffee yet not interfere with its aromatic characteristics.
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The pure flavour compounds described above are highly concentrated and must be diluted in a solvent to allow the blending of multiple oils and easy application to the beans. Common solvents include water, alcohol, propylene glycol, and fractionated vegetable oils. These solvents are generally volatile chemicals that are removed from the beans by drying. Older solvent system technology produced beans which dried up and lost flavour. Current technology uses more stable solvents which leave the beans with a glossy sheen and longer lasting flavour.
The flavour chemicals and the solvents used in flavours must not only be approved for use in foods, but they must also not adversely react with the packaging material and the processing equipment with which they come into contact. Furthermore, they must meet the desired cost constraints.
The Manufacturing Process
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If flavouring is added to beans which have too mild a roast, the coffee lacks significant flavour characteristics, and a flat-tasting beverage results. If the roast is too dark, the added flavour is overshadowed by the taste of the beans. For example, a French Vanilla flavour will be lost on a French Roast bean because the robust quality of the bean will overwhelm the sweet creamy tones of the flavour. The perfect roast colour for flavoured coffee is medium to brown.
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After the beans are roasted, they must be quickly cooled before flavourings can be added. Flavouring the beans while they are still at high temperatures can destroy some of the flavour compounds. In large commercial operations, cooling is done by water quenching, which is a quick, economical process that has the undesirable effect of leaching out some of the natural flavour of the beans. Gourmet beans are dried more carefully, usually by jets of warm air.
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Determining flavour usage
The appropriate amount of flavouring to be used must be determined before flavour oils can be added to the roasted beans. The rate of use typically varies between 2-3%, averaging 2.7% industrywide. A 3% usage rate means that three pounds of flavour oil are added to 100 pounds of roasted beans. The amount of flavouring required depends primarily on the type of flavour and its intensity, as well as the type of bean used and its roast level. Cost constraints also may play a role in determining how much flavouring to apply to the beans, because flavours are relatively expensive. The combination of flavours to be used and the quantity to be applied to the beans is established by experimental trial and error, in which test batches of beans are flavoured with small quantities of oil until the desired characteristics are obtained. This formulation process is similar to the way one decides how much sugar to put in a cup of coffee or tea add a small amount, taste it and, if necessary, add a little more. Once the precise amount is set, the dosage is held constant for that particular flavour oil and roasted bean combination. For different combinations of oils and beans, the usage level must be readjusted for optimal results.
Adding Flavour Oils​
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Flavours are typically added to roasted beans before they are ground. The beans are placed in a large mixer which is specially designed to gently tumble the beans without causing them damage. Examples of this type of mixer include ribbon blenders, drum rotators, and candy pan coaters. The flavours are usually introduced via a pressurized spray mechanism which breaks the oils into tiny droplets which allows for better mixing. Oils must be added to the beans very gradually to guard against areas of highly concentrated flavour called hot spots. The beans are agitated for a set amount of time to ensure the flavour is evenly spread. This process may take 15-30 minutes, depending on the batch size and mixing characteristics of the oil. When the beans are properly coated, they take on a glossy finish that indicates a uniform distribution of oils.
It is also important to note that, instead of flavouring whole beans, flavours in dry form can be blended with ground coffee. In such cases, the flavours are encapsulated in starch or some other powdered matrix. There is enough moisture in the coffee to promote transfer of flavour and color from the encapsulated flavours to the coffee grounds in about 24 hours after mixing.
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Packaging
The finished product is packed in bags or cans as quickly as possible and sealed to prevent contact with the atmosphere. Prior to packaging the container is flushed with nitrogen (an inert gas), a process that removes oxygen from the container. Oxygen can react with components of the flavour oils and the beans and cause deterioration. Coffee beans, once roasted, release their oils and begin to stale quickly when exposed to oxygen. Briefly flushing the container with nitrogen before filling pushes all the oxygen out and ensures freshness. Flavoured beans should be stored in a cool, dark place if they are to be used within three or four weeks. If longer storage is required, the beans may be frozen.
Quality Control​
The quality of flavoured coffees is assessed at various points throughout the manufacturing process. Before roasting, beans which do not meet standards for colour or size are removed. This helps ensure a more even distribution of beans. After roasting, the colour of the beans (which indicates the degree of roast) can be standardized by visual comparisons or with an analytical device known as a colorimeter, which measures the colour of the beans. Beans which are over- or under-roasted are rejected. Similarly, the quality of the flavour oil is carefully checked. Flavourists use various analytical techniques, such as gas chromatography or spectrophotometry, to check flavour quality. These techniques can identify flavour compounds by analyzing their molecular structure. Individual natural and synthetic components are analyzed, as are the finished blended flavours, to ensure the consumer will taste the same quality of flavour from batch to batch. The quality of the final flavoured product is checked with a sensory evaluation technique known as "cupping." This method involves placing 2.5 ounces (7.25 g) of ground coffee in a cup and adding 3.4 ounces (100 ml) boiling water. Both aroma and flavour can be evaluated in this manner. To communicate differences in flavour, the industry uses about 50 specialized terms to describe subjective flavour qualitites, such as earthy, nutty, spicy, and turpeny.
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While there are no specific "coffee standards" the beans in particular must comply with, there are regulated Good Manufacturing Processes (GMPs) for food products. Relevant regulations are provided in the Code of Federal Regulations Title 21.
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Byproducts/Waste
Production of flavoured coffee beans does produce some waste in the form of beans that are rejected for one reason or another. There may be some degree of waste of the flavouring compounds due to batching or weighing errors. There is also waste in the form of solvent evaporation, which occurs during the curing process. These waste materials are not typically considered to be harmful, and therefore there are no special waste disposal requirements.
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The Future
As advances in food technology are made, it is likely that improvements will be made in the manufacturing process for flavoured coffee beans. Better mechanical methods of sorting and roasting beans will lead to more efficient production. More substantive heat resistant flavour compounds will be developed and, ideally, new technology will lead to flavours which cure onto the beans with no heat whatsoever. Of course, flavour chemists will continue to develop new exotic flavour compounds. It is also interesting to note other unconventional methods of flavouring coffees are gaining popularity. For example, instant flavoured coffees have established a place in the mass market. These are made by entirely different processes, such as extracting the coffee flavour from the beans then spray drying, or by freeze-drying the coffee and blending it with flavour agents and other adjuncts. Also worthy of notice is an innovative new flavoured coffee filter, which contains flavouring agents in the filter itself. It is touted as an economical way to serve flavoured coffee and lets the consumer use his/her favourite coffee brand. Similar innovations will become common as the future of flavoured coffee unfolds.