Malting procedure

Fifty gram portions of soybeans were weighed and transferred to perforated, stainless steel malting containers (20 containers for each of the soybean varieties), which were previously disinfected by drying in the UF110 Plus dryer (Memmert GmbH + Co, Schwabach, Germany) for 2 h at 200 °C and then cooled to room temperature. Containers filled with known mass of soybeans were then weighed (the container filled with soybean seeds will be from now on mentioned as the ‘malting kit’). Changes in the moisture content of the seeds during the first step of the malting process (steeping) were calculated based on the changing weight of the malting kit, assuming, that the increase in weight of the kit is equal to the weight of water adsorbed by the seeds. Steeping was executed in the water–air steeping cycle. At the start of the process, malting kits were submerged in the 1.5% sodium hypochlorite solution for 10 min to surface sterilise the seeds. Malting kits were then removed from the sodium hypochlorite solution and immediately washed three times with distilled water. After this process, malting kits were submerged in tap water (disinfected previously by boiling and cooled) at temperature of 18 °C for 6 h, then transferred to the KK 240 Smart Pro (PolEko Aparatura, Wodzisław Śląski) germination chamber (with humidity set at 90% relative humidity and temperature set at 18 °C) for 17 h; then submerged another time in fresh, disinfected tap water (18 °C) for 5 h. After each step, malting kits were weighed to determine changing moisture content of the soybean seeds. At the end of the steeping process, the moisture content of the soybean seeds was equal to 58% (± 0.5%). Soybean seeds were germinated in the germination chamber with the temperature set at 18 °C and relative humidity 90%. Every consecutive 24 h of germination, up to 120 h, 4 malting kits with each of the soybean variety seeds were removed and dried in the UF110 Plus dryer in the following conditions:

This malting procedure resulted in production of 30 different soybean malt samples:

Malts of each type from two separate containers were mixed together transferred to tightly closed containers, to prevent moisture absorption during cooling period. Malts, as well as unmalted soybeans, were ground with the use of Bühler Miag disc mill DLFU (Bühler, Uzwil, Switzerland), with the gap between the discs set at 0.2 mm.