A comparison of barley malt amylolytic enzyme thermostabilities and wort sugars produced during mashing

Authors: Henson, Cynthia; DUKE, STANLEY - University Of Wisconsin; Vinje, Marcus

Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2013
Publication Date: 2/18/2014
Publication URL: http:////dx.doi.org/10.1094/ASBCJ-2014-0130-01
Citation: Henson, C.A., Duke, S.H., Vinje, M.A. 2014. A comparison of barley malt amylolytic enzyme thermostabilities and wort sugars produced during mashing. Journal of American Society of Brewing Chemists. 72(1):51-65.

Interpretive Summary: The industrial process that converts seed starch to fermentable sugars, known as mashing, takes place at high temperatures. Barley seed is typically germinated for 4 – 6 days during the malting process during which time the enzymes that convert starch to sugars are either synthetized and/or activated. These enzymes subsequently function under the high temperature mashing conditions of the brewer’s choice during which time the enzymes, to varying extents, become thermally inactivated thus limiting the yield of the process to less than what is theoretically possible. The work reported here was to determine if germination time impacted the extent of thermal inactivation of the starch degrading enzymes during mashing and thus the amount and identity of the sugars produced under industrial processing conditions. Additionally, we determined if variation in enzyme inactivation and sugar yield was cultivar dependent. The length of germination time did significantly impact enzyme thermostability and the identity and amount of sugars produced during mashing and was cultivar dependent. The impact is that brewer’s yield (fermentable sugar) from raw material (malted barley starch) can be increased by determining the optimal germination time for each cultivar malted and processed under their specific mashing conditions.

Technical Abstract: The industrial process that converts seed starch to fermentable sugars, known as mashing, takes place at high temperatures. Barley seed is typically germinated for 4 – 6 days during the malting process during which time the enzymes that convert starch to sugars are either synthetized and/or activated. These enzymes subsequently function under the high temperature mashing conditions of the brewer’s choice during which time the enzymes, to varying extents, become thermally inactivated thus limiting the yield of the process to less than what is theoretically possible. The work reported here was to determine if germination time impacted the extent of thermal inactivation of the starch degrading enzymes during mashing and thus the amount and identity of the sugars produced under industrial processing conditions. Additionally, we determined if variation in enzyme inactivation and sugar yield was cultivar dependent. The length of germination time did significantly impact enzyme thermostability and the identity and amount of sugars produced during mashing and was cultivar dependent. These results suggest that brewer’s yield (fermentable sugar) from raw material (malted barley starch) can be increased by determining the optimal germination time for each cultivar malted and processed under their specific mashing conditions.