The life of a coffee bean is from picking to post-processing to obtain green beans, then roasted and transformed into the coffee beans we are familiar with, and then comes the final brewing process. It can be noticed that the sequence of almost every step is carried out in one direction, and only this time, so there is no regret for failure. But recently, a customer on Qian Street wanted to "resurrect" the aroma of coffee through "secondary roasting".
This customer on Front Street Street bought a large amount of coffee beans at our store last year and did not finish them all. Although they were not expired, they were already beyond the tasting period and the aroma had completely disappeared. So he had an idea: Since the coffee beans are roasted, can they be put back in the pot and stir-fried?
Well, although it sounds a bit weird, it does seem to make some sense. Front Street cannot completely reject it at once, so today Front Street will give it a try for everyone.
What changes do coffee beans undergo from the time they are freshly baked to the time they are beyond their tasting period?
When the roasting is completed, the coffee beans return to the normal temperature and pressure environment, which contains a large amount of carbon dioxide and begins to be emitted from the inside to the outside. It will be very active in the early stage, usually manifested in hand-made steaming and concentrated Italian oils. It will enter a stable period on the 7th to 10th day. The gas will gradually decrease on the 40th day, until it will be close to zero on the 60th day.
Correspondingly, the extraction of coffee flavor is closely related to gas. In the first few days, the active gas prevents the aroma substances inside the coffee from dissolving outward, which is what we often call the beans. When the gas and flavor enter a stable state after 4 to 7 days, the flavor is significantly reduced at 30 to 40 days, and finally completely lost around 60 days. If stored improperly, coffee beans will also accelerate the above changes, thus shortening the tasting period.
Because of this, drinking coffee requires not only fresh roasting, but also correct storage if you want to lock in the aroma. Regarding the storage of coffee beans, you can check out this article on Front Street "Will the shelf life of unopened coffee beans be extended?」。
Stale coffee beans, second roasting comparison experiment
Combined with the rules mentioned above, when reheating coffee beans that have lost their flavor, you actually want them to contain part of the gas again, thus adding a "coffee flavor". So is this idea really feasible?
Here we chose two single-origin beans with different roasting degrees from the Front Street flagship store, namely the medium-light roasted Front Street Oiran and the medium-dark roasted Front Street PWN Golden Mandheling. The old-date samples were all about 65 days after roasting, while the new-date samples were within 10 to 25 days after roasting.
The first step is to turn on the heat. Pour the old coffee beans into the pot. Keep the heat low throughout the process. Shake frequently to help heat evenly. Control the heating time to 3 minutes. Remove from the heat and pour into a clean container. Wait for the coffee beans to warm up and start brewing:
Front Street Oiran Coffee Bean
Amount of powder: 15g
Pink to water ratio: 1:15
Water temperature: 91℃
Grinding degree: EK43s-10 grid/C40-24 grid (screening rate of No. 20 mesh is 80%)
Filter cup: V60
Brewing method: 3-stage
New date sample: The dry aroma has the sweetness of honey, the "hamburger" exhaust is stable during steaming, the brewed coffee liquid exudes the sweet aroma of nectar, the entrance is the flavor of preserved fruit, sweet orange, blueberry, peach, the body is light, the acidity is medium, with a black tea feel;
Old sample: The color of the coffee beans has obviously become darker, a small amount of beans have been burnt and turned black, and exude the smell of popcorn and walnuts. There is a brief exhaust during steaming, but it is gone soon. The brewed coffee has lost the original floral and fruity aroma, but has a nutty and sweet aroma. At most, there is a caramel flavor, and the taste is also raw.
Front Street Mandheling Coffee Beans
Amount of powder: 15g
Pink to water ratio: 1:15
Water temperature: 87℃
Grinding degree: EK43s-11 grid/C40-26 grid (No. 20 screen screening rate 75%)
Filter cup: KONO
Brewing method: 3-stage
New Date Samples: Freshly Roasted Front Street PWN Golden Mandheling PassAfter grindingThere is an obvious flavor of roasted nuts and spices, and the simmering bulge is obvious and long-lasting. The brewed coffee exudes a caramel aroma. In the mouth, there is the sweetness, bitterness and richness of sugar-free chocolate, with high mellowness and the flavor of toasted bread.
Old sample: The coffee beans are dark brown to the naked eye, and you can already smell a smoky smell before they are ground. The steamed "burger" has an obvious bulge, but the exhaust time is short. The brewed coffee has a bitter taste in the mouth, which can be said to be long-lasting. As for the flavor, Front Street can only say that it has a burnt aroma.
So, can coffee beans that have been stored for too long be roasted again?
Regarding the question mentioned at the beginning, whether secondary roasting can "resurrect" the aroma of coffee, Front Street believes that it cannot. It is not difficult to see from this comparative experiment that no matter which roasting degree of single-origin coffee is used, after the tasting period, the original flavor will disappear, especially the floral and fruity aroma and nutty aroma of medium and light roasting. Reheating only allows the substances on the surface of the beans to continue to coke, which may form a small part of the roasted "coffee aroma", but it is not essentially a flavor converted from green beans, so it will only taste bitter.
The reason why coffee attracts countless people around the world is mostly due to its aroma. Especially for those who pursue specialty coffee, good flavor is hard to come by, and it is undoubtedly a pity to watch it pass over time. This is why Front Street always warns customers who come to buy coffee beans: Don’t buy too much at one time! ! Don’t buy too much at once! ! Don’t buy too much at once! !
