Hop drying
Hop drying is the process of drying the Hopfenblute to hop in beer brewing to use. To ensure that the hops are of very good quality, the ideal time for emptying the drawer is determined during the hop drying process using the electrical measurement method of wire in the drawer .
Measurement options in the kiln
The drying of hops is extremely complex and sensitive. Before every single step in the hop drying process, the optimal point in time for tipping the hops into the next tray must be determined with the help of measuring methods. If the hops are too early, i.e. H. if it is too moist, tipped from the pouring tray into the middle tray, nests will form. The formation of nests occurs due to the increased air resistance in the hop layers. The result is uneven drying of the hops and prolonged drying time. The problem worsens with each additional pour.
In order to achieve even drying of the hops and to reduce the formation of nests, the hops should be stirred up in the discharge tray by hand or with the help of a stirrer.
Drying time
The ideal drying time for hops in the loading tray depends on
Tipping point
In order to determine the ideal tipping point, the relative humidity of the kiln air is determined using an analog or digital hygrometer . The ideal Kippzeitpunkt the kiln is usually between 50 and 60% of relative Darrabluftfeuchte.
Risk of overdrying
Fresh from the kiln, the optimal water content of the hops is 8–10%. However, even at the optimal drying temperature, hops can very quickly and unintentionally overdry. The drying time also plays an important role in the drying of hops. Due to the rapidly changing flow conditions of the drying air, there are temperature differences in the pull-out drawer. Therefore, the water content of the hops cannot be determined there by measuring the temperature and the relative humidity . One possible measurement method for this is the so-called wire in a slipcase.
Structure of the wire in the slipcase
The system was developed by Georg Sterler and has long been sold under the company name GST-electronic and since 2016 under Tec-IN GmbH. A measuring wire to which an electrical signal is applied is stretched in the slipcase. The change in capacitance and resistance of the drying hops in the wire litter area is measured, for which a sufficient amount of hops is required around the wire. During the drying process, the water content around the wire changes and this leads to a change in the electrical signal. The decrease is then displayed by means of a curve or a value on a digital display or a PC screen. In this way, the ideal emptying time can be determined for each hop variety. Since the measured value is slightly influenced by the drying temperature, the temperature should be kept as constant as possible. Since 2017 there has also been temperature compensation for the system so that there is no longer any dependency on the temperature.
Web links
- Hops: drying and conditioning. In: bayern.de. Bavarian State Institute for Agriculture , accessed on April 19, 2017 .