Sequence of operations in barley milling

1. Preliminary Cleaning : Barley is cleaned on machines similar to those used for wheat cleaning, viz. milling separators, drier cylinders or indented dishes, and aspirators. The sizes of sieve aspirators and indents are modified for the comparatively larger size of barley grains.

2.   Conditioning : Conditioning consists in adjustment of moisture content to about 15% by drying or damping and resting for 24 hour.

3. Bleaching : Barley is used to bleach with moisture and sulphur  dioxide. Blocked barley is fed into a vertical earthenware cylinder. Into which steam and sulphur dioxide are injected. The quantities used are 1-2% of moisture and about 0.04% of sulphur dioxide and solution of sulphurous acid (H2SO3) or of sodium disulphide (NaHSO3) can be. The treatment take about 20-30 min time, after that the barley is binned for 12-24 hour for the bleaching to take effect. Excessive quantities of sulphur residues in the final product should be avoided.

4. Blocking and Pealing : Both blocking and pearling of barley are abrasive scouring processes differing from each other merely in degree of removal of the superficial layers of the grain batch machines or the rate of throughput  in continuous working machine.

5.  Aspiration : Aspiration of the pearled grain to removes the abraded portions and cutting of blocked barley into portions known as grits and it is similar to those methods done for aspiration of oatmeal. In Germany, the blocked barley is first cut into grits, the grits graded by size and then sounded in the pearling machine.

6. Polishing : The pearl barley is polished on machines similar to those used for pearling but equipped with stones made of hard white sandstone instead of emery composition. The average yield of barley is 67% of the whole barley.

7. Steam Cooking and Flaking : Barley flakes are made from pearl barley by steaming and flaking on large diameter smooth rolls.

8. Drying : The flakes are dried to about 10.5% moisture content before packing. Barley flakes are made from pearled barley has been used as flavouring ingredients in specially breads in the USA.

            Pearl barley is used for sups and dressings and for the manufacture of puffed barley, a read to eat breakfast cereal. Pearl barley blocking removes part of the husk, this process must be accomplished with the minimum of injury to the kernels. The pearling carried out in two stages, removes the remainder of the husk and part of the endosperm. The three processes remove about 5%, 15% and 11%, respectively to yield a final product representing about 67% of the grain.