By Randy Pope
Back in the 60s, if you asked for a cup of decaffeinated coffee you would almost always be brought a beverage made from a powder. There just wasn’t enough demand to justify fresh-brewed decaffeinated coffee. Gradually more people demanded decaffeinated coffee, either due to health concerns or just because they want to sleep better at night.
Customers also gained more education concerning coffee, and they came to expect a superior cup. Eventually, they demanded the same quality beverage in a decaffeinated coffee that they got in a regular cup. They wanted high quality coffee made with the same ratios and with similar strength that they got from a caffeinated beverage.
Now in theory, this shouldn’t be difficult to serve: decaffeinated coffee and caffeinated coffee are usually brewed in the same coffee brewer. But even though there is a growing demand for superior tasting decaf, there are no published standards for brewing this significantly different coffee. I want to suggest that separate brewing standards should be used for decaffeinated coffee.
Why separate standards?
According to the standards published by the Speciality Coffee Association of Europe (SCAE), a range of strength from 1.20%-1.45% coffee soluble material in the beverage is the most enjoyable. Soluble concentrations (or the percentage of coffee flavoring material to the amount of water in the beverage) below 1.00% were considered weak and above 1.50% were considered strong.
In addition, extraction (yield) of less than 18% of the soluble material was determined underdeveloped, and yields greater than 22% were determined to have removed undesirable bitter flavors. The extraction (amount of material removed from the ground coffee) limits were determined to be within a range, of 18- 22% of the original weight used. Given atmospheric conditions, the maximum amount that you can extract from coffee is about 30%.
With decaf, the bean is often decaffeinated through a process that washes it with water, strips the caffeine from the water source, then passes the water back over the beans to replace some of the qualities that were taken out. In the course of this "bathing," the bean swells, something a regular bean first does during the roasting process. It’s as if you took coffee beans you planned to use out of the bag, soaked them and then dried them out so that you could use them tomorrow.
Because of this water treatment, the bean does not roast the same way as its non-treated counterpart. During roasting, the bean fiber does not explode to the extent it would if the bean was not treated. As a result, the interstitial surfaces inside the bean created by roasting are minimized. A decaffeinated bean often looks darker than a regular bean even with an identical roast.
When the ground bean gets to the brew funnel, it behaves differently. Some of the waxes and oils are gone, removed by the decaffeinating process, so the bean doesn’t absorb water in the same way. Since the beans are tougher, they do not extract as easily.
Sometimes the coffee is also roasted longer to increase color, and often decaffeinated coffee is several shades darker than regular coffee of the same varietal.
If you had a sack of beans and decaffeinated half, leaving the other half with caffeine, then brewed them identically, the resulting beverages would have different colors and extractions. That’s because, from 2% to 5% of the bean’s mass was extracted during the decaffeination process. Decaffeinated beans are also a little tougher to grind, because the cell structure doesn’t swell up as much in the roasting process.
Extract less for better decaf
As a result, if you aim to extract 18% to 22% of the bean during brewing knowing that 3% of the decaffeinated bean is already gone, you will over-extract the decaffeinated bean -- extracting from 21% to 25%.
A decaf brewed with up to 20% of extraction will maintain the strength of brew, but a higher% of extraction will produce a beverage that is often over-extracted. This happens because part of the bean was removed during its bath in the decaffeination process. I would like to recommend that you aim for extraction in the left side of the coffee brewing control chart -- less than 20% of extraction for decaffeinated coffee.
Another factor that can affect the quality of the beverage is coffee-to-water ratio. Because decaffeinated beans go through two processes the regular bean doesn’t – the decaffeination process and additional shipping back to the packer – the price of decaf is often higher than regular coffee. So, to bring that price per cup down to the level charged for regular coffee, the ratio of coffee to water is sometimes increased -- less coffee is used and more water. For best flavor, maintain the SCAE recommended coffee-to-water ratio (92.2 – 120.5 grams of coffee to 1,814 grams of water).
Decaf coffee also acts in a different way in the funnel -- coating and floating rather than extracting and sinking. It doesn’t want to give up its material -- it just wants to float around the brew funnel. Brew time may need to be adjusted to allow for this quality of decaffeinated coffee.
Decaf coffee is here to stay and we need to have brewing standards that address this increasingly popular type of coffee. Because no standards have been developed yet, it’s best to keep in mind that a superior cup of decaffeinated coffee probably needs less extraction than regular coffee. Regardless of the coffee that you begin with, if it isn’t brewed properly, you will serve your customers a watery, tasteless cup. Attention to brewing and knowledge of the special characteristics of decaf will result in a high-quality beverage every time.
Author Randy Pope is director of brewing center, Bunn-O-Matic Corporation