Soaking in food industry

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1. OBJECTIVE


The objective of soaking, e.g. of vegetable seeds, such as lentils, is to moisten and soften the seeds to reduce the cooking time or to aid in seed coat removal. In the malting process, the objective of soaking is the uptake of water to activate the germination process in the kernel (BAT in the Food, Drink and Milk Industries, June 2005).


2. FIELD OF APPLICATION


Soaking is predominantly applied in the processing of vegetable seeds. It’s also applied with grain, where the grain is soaked in the malting process prior to germination. This is often called steeping (BAT in the Food, Drink and Milk Industries, June 2005).


3. DESCRIPTION OF TECHNIQUES, METHODS AND EQUIPMENT


Soaking is performed by putting the vegetable seeds in water for a specified time. The time needed varies, depending on the seed variety and species and with the length of storage and storage conditions. Traditionally, dry beans are soaked for 8 to 16 hours 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 to 15% to anywhere between 30 to 50%, depending again on the above conditions. 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 change the grain can be aerated or the CO2 can be extracted. The steeping process takes one to three days (BAT in the Food, Drink and Milk Industries, June 2005). The figure below shows an example of a steeping procedure:


Soaking food.jpg


4. COMPETITIVE TECHNOLOGIES AND ENERGY SAVING POTENTIALS


a) Changes in the process

No information is available.


b) Changes in the energy distribution system
  • Heat recovery from waste streams: (Joanneum Research)
Soaking requires warm water, in temperatures that do not exceed the level of 25°C. Therefore, heat can be easily recovered from waste streams of the process.


c) Changes in the heat supply system

No information is available.


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