Characteristics of Japanese malting barley varieties and optimization of their malting process.

Otsuka, S.

Abstract
Legislation intended to protect the Japanese agricultural community requires that all barley grown in Japan which is of an approved malting variety and passes an official quality inspection must be malted and used for brewing or distilling, facing the country's maltsters with the problem of producing acceptable malts from a highly variable barley supply, a significant portion of which is of quite poor quality. Comparative micromalting trials of three Japanese barley varieties, Amagi Nijyo, Misato Golden and Tone Nijyo, using Harrington barley (from Canada) as a standard of comparison, are described. It was found that Misato Golden, which tends to be inadequately modified when malted by the standard method, can be made into a reasonably good malt by prolonging the steeping process, since its usual poor performance appears to be caused by an insufficient moisture content at the onset of germination. Further trials were carried out in order to develop methods of coping with the wide range of protein levels occurring in Japanese barley. It is recommended that the germination temperature should be varied according to the protein content; low protein barley should begin to germinate at 23 degrees C, falling to 20 degrees C after one third of the period of germination has elapsed and then to 17 degrees C after two thirds of the germination time, whereas high protein barley should begin at 23 degrees C, be cooled to 17 degrees C for the middle third of the germination period and be allowed to warm up to 23 degrees C for the final third.
Keywords : barley germination malting modification moisture content protein quality steeping temperature time variety