Hop cones when picked contain 75-80% water. They must be dried immediately. The drying process takes place using a dryer.
The dryer consists of a low-pressure steam boiler, from which the steam directed by the heater gives off heat to the air flowing upwards. Heated air flows through four layers of hops thick 12-15 cm each. The drying of the hops continues 5-6 hours, at an air temperature of 50-60 ° C. Dried hops contain 8-9% water.
After hops are dried, they must undergo a so-called. sweating, to equalize the humidity in the whole mass of cones. The process continues to say the least 2 weeks. The hop warehouse should be dry and airy - equipped with blinds or opening windows. Windows should be darkened, preferably painted with blue paint. When hops are stored in bulk, they are mixed every few days. By mixing, we facilitate the supply of air and balance the humidity in the cones.
After sweating, hops should not stay in heaps for a long time. It should be pressed into bags, even if shipment is not anticipated. When packed, the hops get slightly moist, so that the cones do not crumble. Moisturizing occurs naturally, i.e.. by absorbing moisture from the air. Therefore, it is best to pack the hops on cloudy days, when the air is humid.
Hops are packed in large bags, called wańtuchami. They have dimensions: length 200 cm, width 90-100 cm, relatively length 220 cm, and the width 110 cm. Wańtuchy are numbered and the weight of hops is marked on each of them, in a smaller bag it should be 50-60 kg, and more 60-80 kg.
During the storage of raw hops, the temperature changes inside the hops are periodically controlled. For this purpose, a wire, sharpened at the end, is inserted inside the tube. After removing the wire, check how hot it is by placing it on the cheek or neck, as the most sensitive to body surface temperature.
Modern apparatuses are used to control the temperature of hops, whose design is based, inter alia, on the measurement of variable current resistance depending on the humidity of hops.
In recent years, the apparatus of the West German company Simens has found widespread use in practice, typ Multi zet FM.
A batch of hops showing increased humidity must be dried to the optimum humidity 10-12%.
Raw hops are sulfurized, and in the case of excessive humidity, drying and sulfurization, and then baling, that is, packing pressed hops into jute bags.
The hops are pressed using presses; hydraulic. The weight of hops in the bag, the so-called. balocie, is 150-200 kg. Pressing hops reduces its hygroscopicity by hindering the access of air and moisture.
Air humidity, light and heat accelerate the oxidation of valuable bitter acids and the development of microorganisms and biochemical processes that cause aging of hops. Hop sulfurization limits these processes, however, it does not rule them out. Therefore, compressed hops should be stored in dry warehouses, dark and cool. Hops are stored in artificially cooled warehouses at 0 ° C, In warehouses, bags of hops are placed next to each other on wooden grids, which protects it from self-heating.
In many foreign breweries, the Weiner hop preservation method gives a good effect. The hops bale is placed in a tightly closed container, from which the air is pumped out, then carbon dioxide is introduced into the reservoir. In such impregnated hops, the bitter substances are protected against oxidation, provided the oxygen inside the package is completely removed.
Research by the Fermentation Industry Institute has shown, that the loss of bitter value in hops during one-year storage at a temperature of approx. 0° C are 10-17%, and in non-refrigerated warehouses 25-40%.