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Tech. Q. Master Brew. Assoc. Am., 1987, 24(1), 33-37. English

Practical plant studies on barley respiration during the steeping process.

Haley, P.E. and Stokes, C.H.

A study has been made of the effectiveness of aeration and removal of carbon dioxide during the steeping period. Oxygen and carbon dioxide levels have been monitored by sampling steep tanks at three different levels using a vacuum pump to withdraw sample for presentation to a Drager C02 tester or a 1L 545 oxygen meter. A number of steeping systems have been examined and technical details are given. From the data collected it was recommended that aeration during steeping should be uniform and vigorous in the submerged periods with a minimum of 25 cu ft of oil free air/mm/1000 bushels barley using a minimum air jet density of 1 jet (0.0625" orifice)/3.2 sq ft of tank water surface. Carbon dioxide should be removed during the rest period following drainage using a minimum suction of 100 c.f.m./1000 bushels barley. The temperature and humidity of air passing through the grain bed should be controlled with maximum steep temperature 62oF and maximum steep barley temperature 65oF at steep out. Aeration using nozzels has been compared with aeration using stainless steel sintered stones. These latter produce microbubbles of air, increasing the solubility of oxygen in the steep water and reducing channeling. Tests will continue to determine which system is superior.
Keywords : barley carbon dioxide malting oxygen respiration steeping