How do you keep the coffee beans at home? how long do you keep the coffee beans for long?

Coffee beans are fresh ingredients, not dry goods.

"No, the water content of roasted coffee beans is very low, and the water activity is so small, isn't it the same as practical information? "

The fact that you can say "water activity" means that you know something about food science, but roasted coffee beans (cooked beans) are fresh ingredients not because of their high water content, but because their main flavor components are highly volatile.

The low "water activity" of ripe beans gives it a dry shelf life, but the high volatility of its flavor ingredients forces us to preserve it according to the standard of fresh ingredients, otherwise it will not taste good.

If you buy a batch of rare high-quality goods, in addition to sealing the use of one month's dosage, how to preserve the extra quantity?

To put it simply, there are only two ways to prolong the "taste period" of ripe beans: low temperature and high pressure.

Cryopreservation

Like most ingredients, low temperature helps to reduce molecular activity, thus slowing down the rate of chemical change in food denaturation. The low temperature here refers to the temperature below-18 ℃, which is also the industrial standard for frozen storage of most fresh foods.

The freezer of a household refrigerator is usually kept at 3-5 ℃, which is obviously not appropriate. A freezer is a possible option, but how do you know if it has reached-18 ℃?

Go and buy a box of ice cream. The ice is in the freezer in your home. Take out the lid a week later and see that the ice cream remains intact or as hard as iron, and the freezer temperature must be lower than-18 ℃. It is common to turn into a high-grade milkshake, which does not help to preserve ripe beans.

An individual has done an experiment in which bags of half a pound of fresh cooked beans are bagged in the freezer and taken out half a year later. Compared with the freshly baked cooked bean cup test, except that there is no bad taste, the original flavor is reduced by volatilization, but it still retains about 70% of the good taste.

High pressure is effective, but it is expensive.

The Le Chatelier principle principle in chemistry tells us:

Chemical equilibrium is a dynamic equilibrium, and if a factor affecting the equilibrium is changed, the equilibrium moves in a direction that can weaken the change in order to counteract the change.

The aging process of fresh cooked beans is always accompanied by gas emissions, so you will see the powder layer bulging up when you hand-flush the fresh coffee beans. So, if we put high-pressure nitrogen into the container for fresh cooked beans, can't we turn back the aging balance of cooked beans and slow down the rate of aging?

The answer is yes. Italian bean merchant Illy has made great achievements in using this method to preserve barrels of cooked beans so that their products can be sold all over the world. But you have to order expensive pressure containers for this method, sometimes the container itself is more expensive than cooked beans.

Is it all right to vacuum?

The concept of vacuum preservation of food comes from isolating the effect of oxygen on ingredients, but for coffee beans, it promotes the emission of gases in cooked beans faster, shifts the balance towards aging, and increases the speed of aging. So vacuum (or low pressure) is the wrong method.

The function of one-way breathable bag

The industry usually uses one-way breathable bags to pack cooked beans, and some companies claim that it can keep them fresh more effectively, which is actually wrong. The breathable valve of the one-way breathable bag is designed to relieve the high pressure in the bag so as to prevent the bag from rupturing due to a large amount of gas discharged from cooked beans. When it comes to keeping fresh, if the bag is strong enough, it is better to let the gas from cooked beans form high pressure in the bag.

To sum up, if conditions permit, try to use up the coffee beans within a month after baking; if you have to preserve them, freezing below-18 ℃ or injecting high-pressure nitrogen into a strong airtight container is probably the only effective way to preserve cooked beans on earth.