What is sublimation?
Freeze drying (aka lyophilization) is a process used in the food industry to remove water from foods to increase shelf life. It consists of several stages. First, the temperature of the product drops (typically around -40°C), which causes the free water to freeze. The bound water is then removed from the product by raising the temperature, typically in a vacuum environment. Due to the low operating temperatures and gentle drying conditions, the product retains the maximum of beneficial substances, taste and aromatic qualities.
How to make freeze dried instant coffee?
The process of making a ready-made drink, which retains its valuable properties to the maximum, takes place in several stages.
Let's start at the very beginning and explain all the way from mixing to finished crystals.
The first stage is the creation of a mixture of grains of different varieties.
Raw green beans, carefully selected by coffee tasters, enter the factory where they are carefully sifted and machine cleaned to remove any residue that may have entered the batch.
This is followed by the roasting stage, in which the initial green color of the grains changes to the more familiar brown. The number of grains loaded simultaneously can be up to 420 kg. The beans are heated above 200°C to achieve a moderate roast, ideal for instant coffee.
Third stage crushing: roasted coffee beans are sent to be ground in an industrial mill. This is not the coffee grinder you might find on your kitchen counter. Some are capable of grinding up to 1500 kg of coffee per hour.
In the next step, the crushed beans (they have larger pieces than our homemade grind) are infused in hot water - just like we do with regular coffee. Thanks to this process, the aroma, flavor and color of coffee is removed from the crushed beans, resulting in a very strong concentrate (much stronger than what we have in a mug).
They are also extracted from the beans by pumping nitrogen gas from the ground coffee to minimize the loss of aromatic substances. This flavored vapor is placed in a special tank in anticipation of its culmination.
The finished concentrate is frozen at low temperature in a freeze dryer, which also creates a vacuum to reduce pressure.
In the final, third step, the frozen concentrate is dried, during which all water is removed from it. At the same time, as a result of the formation of coffee crystals in the machine, it immediately passes from the frozen state to the gaseous state, completely bypassing the liquid phase.
The finished crystals are treated with the same flavored steam collected before. This technology is called "flavor return" and is used to improve the taste and aroma characteristics of coffee.
At the final stage, the finished light brown crystals are packaged in jars, which soon fall on store shelves.
Why is freeze-dried coffee considered better than powdered and granulated coffee?
The technology for obtaining freeze-dried coffee has emerged relatively recently and is today considered to be of higher quality and more successful than its predecessor method of making instant coffee powder.
The difference is really noticeable.
Unlike freeze-dried coffee, ground coffee is prepared using a highly aggressive hot drying method. In the freeze stage of freeze drying, ground coffee is processed at high temperatures. As a result, almost nothing remains of taste and aroma, and the beneficial qualities of the drink are much less.
Granular coffee and powder coffee making technologies are the same, only in the final stage the powder particles stick together as granules.
What is the composition of freeze dried coffee?
Despite the fact that instant coffee manufacturers insist on the identity of regular and freeze-dried products, in fact, of course, there is a difference both in taste, aroma and composition. However, it is indeed considerably less than between conventional coffee beans and instant coffee powder/granules.
Like regular coffee, freeze-dried coffee contains:
caffeine,
antioxidants,
vitamin b,
minerals (potassium, calcium, magnesium, phosphorus, sodium, selenium),
a small amount of carbohydrates (0.3 g per 100 g of product),
0 fat and 0 protein,
About 1 kcal per 100 g of drink.
The harms of freeze-dried coffee;
The use of freeze-dried coffee (like any other) should be limited to people with heart disease, high blood pressure, diseases of the excretory system, sleep and mental disorders. It is also not recommended to serve instant coffee to young children, and pregnant and lactating women should reduce the amount of this beverage in their menu. And doctors do not recommend drinking coffee on an empty stomach and in the afternoon.
Does freeze-dried coffee contain less caffeine?
Freeze-dried coffee, like any instant coffee, usually contains slightly less caffeine than coffee beans. A cup of instant coffee made from 1 tsp. (2 g) of dry matter may contain 30-40 mg of caffeine (depending on the brand), while a regular cup of coffee contains 70-140 mg. Therefore, instant coffee should reduce caffeine intake.