The objective of soaking (e.g. of legume seeds) is to moisten and soften the seed to reduce the cooking time or to aid in seed coat removal. In the malting process, the objective of soaking (steeping) is the uptake of water in order to activate the germination process in the kernel.
Field of application
Soaking is predominantly applied in the processing of legume seeds. It is also applied with grain, where the grain is soaked in the malting process prior to germination. This is often called “steeping”.
Description of techniques, methods and equipment
Soaking is performed by putting the legume seeds in water for a specified time. The time needed varies, depending on the seed variety and species and with the length and storage conditions. Traditionally, dry beans are soaked (8 – 16 h) in cold water with appropriate hardness. High temperature soaking accelerates hydration. To steep the grain, the grain is immersed in water at about 16 C, ranging from 10 to 25 C, depending on the equipment, the process parameters, the raw material and the finished malt to be obtained. During steeping, the moisture content increases from 12 -15 % to about 45 %, ranging from 30 to 50 %, depending on the equipment, the process parameters, the raw material and the finished malt to be obtained. During steeping, the water in the steep tanks is changed one to three times. Alternate dry and wet stages are applied. During the wet stage, the grain is aerated continuously or at intervals. During the dry stage, the grain can be aerated or the CO2 can be extracted. The steeping process takes one to three days.