Can Decaf Coffee Beans Be Eaten? The Story and Characteristics of Decaf Coffee Beans, and Why They Have More Defective Beans

Possible Hypotheses About Defective Decaffeinated Coffee Beans

Decaffeinated coffee beans often show defects after processing. Compared with unprocessed beans of the same grade, this phenomenon is clearly abnormal. After discussion, we proposed several possible hypotheses:

1. Improper Storage Conditions

Decaffeinated beans may not have been stored properly. After water treatment, the bean structure itself is not very tight, and flavors are more easily lost than in normal beans. Under improper storage conditions, the green beans may undergo undesirable changes.

2. The Activated Carbon Treatment Process

The method described earlier is the commonly used Swiss Water Process, which includes an activated carbon treatment step. Activated carbon is a very aggressive substance, so we can hypothesize that during this step, not only caffeine but other substances are filtered away as well. Even some structural components might be partially removed, which could easily cause defects and the loss of content in the beans.

3. High-Temperature, High-Pressure Processing

Coffee beans are, after all, a type of bean, similar to mung beans or soybeans. When we make mung bean soup or soy milk, we soak the beans overnight to soften them, making them easier to cook or blend. Caffeine removal always occurs in solution and requires high temperature and high pressure, which increases the porosity of the green beans. After activated carbon filtration and heat drying, it is difficult for the beans not to lose some of their content.

Whichever hypothesis is correct - or perhaps all three - the result is obvious: the processed green beans have a loose structure, reduced volume, low gloss, many defects, and an unpleasant odor. Improper storage may even have given them oily and other off-notes, suggesting severe flavor loss.

Second Roasting Experiment Results

Judging from the characteristics and aroma of the roasted decaffeinated beans, our hypothesis and approach of roasting a second time were correct. After raising the initial temperature and shortening the roast time, we were pleasantly surprised to find that some of the defect flavors, such as the off-notes, were eliminated. The previously thin aroma gained complexity and became richer and more mellow.

Different roast development creates different flavor changes. Although we do not yet understand exactly which substances changed and how, this experiment pointed us toward an excellent research direction - which is what excites us most.

Second Roasting Temperature and Time Control

Through experimentation, we found that the difficulty of second roasting lies mainly in setting the initial temperature. We planned to use the endpoint temperature of the previous roast - or rather its drying phase - as the starting temperature of this roast. Although little literature is available for reference, based on the condition of the beans across several sessions, we ultimately set the initial temperature at 200°C. Combined with the loose bean structure, we completed this roast in just 6 minutes, with a development time of 1 minute and 20 seconds when the beans left the roaster.

FrontStreet Coffee Recommendation

If you prefer to avoid caffeine altogether, a decaffeinated single origin is one option - but if what you are really after is a low-bitterness, low-acidity cup, FrontStreet Coffee's range of arabica espresso blends is well worth a look. The FrontStreet Black Cocoa Blend uses 100% arabica beans with ample crema and a mellow, balanced body at a friendly price - ideal for beginners or cost-conscious cafe owners. The FrontStreet Premium Blend pairs Brazil Cerrado with Colombia Huila for the most familiar classic espresso character, and has anchored the shop's americanos and lattes for nearly a decade.

Those who favor full body with no sourness can choose the single-origin options instead: the dark-roasted FrontStreet PWN Indonesia Golden Mandheling, rich and lingering with herbal and dark chocolate notes and a faint earthy sweetness, or the FrontStreet Brazil Queen Estate, low in acidity with pronounced nut and cocoa aromas and caramel sweetness - equally at home in pour-over, espresso, or a moka pot. The Papua New Guinea Paradise Bird, an AA-grade Typica grown at 1,600-1,800 meters on volcanic rock soil and triple washed, offers a clean, sweet cup often called the "little Blue Mountain" - another superb choice for drinkers who avoid acidic coffees.