Coffee common sense some suggestions on the preservation of raw coffee beans

The preservation of raw coffee beans is generally affected by the following: 1) the water content of raw coffee beans, 2) the temperature of the surrounding environment, 3) relative humidity, the water content of the coffee bean itself: about 10-11% water content is our general understanding of a batch of good raw beans, but where does this number come from? What is its credibility? Kenya conducted an experiment in which four batches of raw coffee beans each had a different water content at a room temperature of 10-35 degrees Celsius. 5%, 10. 8%, 12. 7%, 15. 5% stored for 12 months, the water content is 10. 8% of this batch of coffee beans performed best.

What about the temperature? Its effect on raw beans must be linked to the relative humidity of the environment. An excellent team in Brazil has done a study on this. During transportation for more than a month and a half, the temperature difference may be more than 40 ℃ (7 ℃-47 ℃), while the relative humidity may be more than 30% (20% 50%). This makes the water droplets condense in the box, and the sacks containing coffee beans become moist. Beans begin to mildew and produce OTA in fact, temperature, relative humidity and water content of raw coffee beans, mold and toxin production can all be linked to a very important factor, water activity, what is water activity? Technically, the water activity (aw) of a substance is the ratio of the vapor pressure of the water in the substance to the vapor pressure of the water in pure water at the same temperature. To put it simply, we store raw coffee beans at 25 ℃, and the water activity of coffee beans is the ratio of vapor pressure of coffee beans to that of pure water at 25 ℃. From a more practical point of view, water activity is the energy of water in a specific situation and at a specific time. For example, raw coffee beans are in transit at 30 ℃, relative humidity 70%, compared with 20 ℃ in the warehouse and 60% relative humidity. The activity and energy of water are different, because the molecules move faster and more at high temperature. in addition, the water in coffee beans is less likely to be lost when the relative humidity is high (the molecule is less likely to cross the cell wall and reach the other end, because the other end is rich in moisture). Obviously, there are several environmental factors that affect water activity. The importance of water activity comes from the fact that it determines the ease of movement of water molecules in coffee beans or other foods.

Unfortunately, however, the loss of water in the coffee bean will take away other substances around it (such as aromatic chemical compound: trigonelline) because of its chemical properties, so we can conclude that when the relative humidity in the air around the raw coffee bean is too low, the water in the coffee bean will begin to lose and leave the coffee bean, while the other small molecules around the water molecule will be tied to the water molecule and leave together. Of course, it may contain aromatic odor compounds. On the contrary, if the relative humidity in the air around the raw coffee beans is too high, the water in the air will enter the coffee beans, and of course, it also brings a lot of other surrounding odor molecules into the raw beans, which may not be what we want. For coffee beans, about 11% water content and about 60% relative humidity are the most appropriate, that is to say, under these conditions, the water in coffee beans is the most difficult to leave, and the water in the air is the least easy to enter. Everything remains in the most primitive state, and naturally there will be no change in its aromatic molecules.

Generally speaking, the higher the water content in raw beans, the higher their water activity. But they are different! For example, two raw coffee beans with the same water content will have different water activity due to different surroundings (different relative humidity) and different bean states. for example, coffee beans will increase their water activity due to damage to the solid or cell membrane after several freezing and thawing, so that moisture and aromatic molecules become easy to get in and out, even if the relative humidity around the air is about 60%. It still doesn't help. From the above we can understand that water activity is an important key to preserve the quality of coffee beans, which depends on the water content, relative humidity and temperature of coffee beans. Basically, the most appropriate activity of coffee raw bean water is about 0. 55-0. 604, the water activity is between 0. 6-0. 7 will promote the Mena reaction, making it possible to start even at room temperature, but higher than 0. 7's water activity will promote mold growth and produce OTA, of course, the higher water activity will make the water and aromatic molecules in coffee beans easier to exchange with the surrounding water and aromatic molecules, so the cleanliness of the warehouse is also very important! However, can we strengthen it by improving some tools or equipment? 1. Build a warehouse with constant temperature and humidity! You can set the temperature at 17 ℃ and the relative humidity at 60% to simulate the most suitable environment for the storage of raw coffee beans. two. Give it a sealed environment! Sealed bags packed into small bags to prevent the substances in raw coffee beans from mixing with the warehouse environment, vacuum packaging will be better if possible. Let's give everyone a cup of better coffee!