The Effect of Barley Adjuncts on Free Amino Nitrogen Contents in Wort

Masaaki Yano^1,3, Hideki Tsuda², Takeo Imai², Yutaka Ogawa² and Motoo Ohkochi¹
¹ Planning section, Technology Development Department, Production Division, Kirin Brewery Co., Ltd., 2-10, Shinkawa, Chuo-ku, Tokyo, 104-0033, Japan.
² Research Laboratories for Brewing, Technology Development Department, Production Division, Kirin Brewery Co., Ltd., Technical Center, 1-17-1, Namamugi, Tsurumi-ku, Yokohama, 230- 8628, Japan.
³ Corresponding author. E-mail address: myano@kirin.co.jp

J. Inst. Brew. 114(3), 230–238, 2008 | VIEW ARTICLE

ABSTRACT
Free amino nitrogen (FAN) and other low-molecular-weight nitrogen compounds (LNC) are highly important as nutrients for yeast. Many different types of low-malt beer exist around the world, some of which are produced with barley as an adjunct. In these cases, inhibitors contained in barley are known to influence the amount of LNC in wort. Accordingly, it is important to investigate which proteinase class is key in producing these compounds. By investigating the relationship between the FAN contained in wort produced from malt and barley (barley adjunct wort) and malt proteinase activity, it was found that cysteine proteinase and 1,10-orthophenanthroline (O-Phen)-inhibitable metallo proteinases had a significant correlation to the barley adjunct wort FAN levels. In addition, the relationship between malting conditions and these proteinase activities was investigated and the conditions defined for maximal production of proteinases as follows: steeping degree, 50%; germination temperature, 12°C; germination days, 6 days; water spray,

Key words:
Barley, free amino nitrogen, malting, plant hormone, proteinase.