Grain-drying methods

These days most grain is bulk-handled from the combine into and out of store. In some years, when all the cereals are combined at below 15% me, no drying will be necessary, only possibly cooling. 

Below are listed the most important methods of drying grain  

Wet grain (over 22% me) rrray reqtrire two passes through the drier, taking out about 5% moisture each time. 

Grain can be stored in bulk for up to one month at 16-17% me, but for longer term storage it should be dried down to 14% me. Only fully ripe grain in a dry period is likely to be harvested in the UK at 14% moisture. In a wet season, the moisture content may be over 20% and the grain may have to be dried in two or three stages if a continuous-flow drier is used. 

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Kristensen E F (1998), New drying method for improvement of the quality of malting barley and bread grain. Proceedings of the European Association of Agricultural Engineers, Ag Eng 98, Norway. Abstract 98-F-011, p. 324. 

Microwave moisture analyzers are the next step in gravimetric analyses by focusing on much shorter drying times. Currently there are only a few matrices recognized by the AOAC for use in the microwave drying method (Sullivan and Carpenter, 1993). Although there hasn t been a collaborative study for AOAC approval to support other matrices, the micro-wave moisture analyzer has been used successfully in such matrices as grains (Okabe et al., 1973) and flours (Davis and Lai, 1984). 

The procedure has been suggested as a means for rating the performance of grain dryers, but it may be applied with equal success to other dryer types or drying methods. 

Feedback control based on the exhaust-air temperature was the first automatic control method used in cross-flow grain-drying plants. However, due to the uncertain relationship between the outlet-air temperature and the outlet grain moisture content, this control strategy had proven to be ineffective [47,48]. 

About 20% of the protein is in the wheat germ and is not important in the baking process. However, the other 80% (in the endosperm) is very important. It can be measured in various ways. For example, protein quantity is assessed by the Dumas test and by the near infra-red reflectance (NIR) technique which is a very rapid dry method. Note in addition, NIR analysis can measure moisture content as well as grain hardness. 

In order to dry the crystals, the Buchner funnel is inverted over two or three thicknesses of drying paper (i.e., coarse-grained, smooth surfaced Alter paper) resting upon a pad of newspaper, and the crystalline cake is removed with the aid of a clean spatula several sheets of drying paper are placed on top and the crystals are pressed flrmly. If the sheets become too soiled by the mother liquor absorbed, the crystals should be transferred to fresh paper. The disadvantage of this method of rapid drying is that the recrystallised product is liable to become contaminated with the Alter paper flbre. 

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