VIEW ARTICLE    DOI: 10.1094/ASBCJ-53-0104

Barley Malt Limit Dextrinase: Its Extraction, Heat Stability, and Activity During Malting and Mashing. Michael Sissons, Marcus Taylor, and Michael Proudlove, BRF International, Lyttel Hall, Coopers Hill Road, Nutfield, Surrey, U.K. RH1 4HY. J. Am. Soc. Brew. Chem. 53(3):104-110, 1995. Accepted December 13, 1994.

The importance of limit dextrinase in malting and brewing has been reevaluated by using a specific dyed substrate assay. Maximum activity can be extracted from malt by a relatively lengthy extraction at pH 5.0. Hammer milling improves the extraction of the enzyme, compared to roller milling. The released enzyme loses activity quickly in a mash at temperatures above 63°C, but when in its bound form, the enzyme retains activity for longer. Gibberellic acid applied at relatively high rates increases the levels of the enzyme in malt after day two of germination. The kilning regime used for lager and ale malts (using the pilot facilities at BRF International) reduced the activity of the green malt by 24 and 85% respectively. The free enzyme was more susceptible to heat inactivation. Mashing conditions that promoted release of the bound enzyme led a significant alteration of the wort carbohydrate composition in favor of increased fermentability. Keywords: Bound, Free, Kilning, Limit dextrinase, Mashing