gibberellins

are a family of plant hormones that are responsible for stimulating growth and seed germination, which includes gibberellic acid (GA). Gibberellins play an integral role during plant development, and therefore they have an overall effect on plant-based spirit and cocktail raw-material quality from mint to barley. Their role in the biochemical and structural degradation (modification) of the cereal grain endosperm (i.e., rye, wheat, and barley) and hydrolytic enzyme synthesis during malting is what makes it of particular interest to distillers and brewers alike.

The synthesis of gibberellins begins in the embryo after its carbohydrate reserves have been depleted. They then migrate into the aleurone, where they stimulate the production of hydrolytic enzymes for modification upon the start of germination. These enzymes, in addition to those from other plant tissues, are key to malting, as well as beer and whisky production; during mashing, they allow the starch in the endosperm to be solubilized and further degraded into fermentable sugars for the yeast to convert to alcohol.Exogenous forms (GA) have found use in malting as an additive to the water in which the grain is initially steeped, in a process called “gibbing,” which helps to ensure an efficient and homogeneous modification. With the gibbing process, grains are abraded gently to damage the kernel, which allows for more rapid and increased hydration. See kernel. The supplemental GA increases the rate of starch and protein-degrading enzyme production, which accelerates modification and leads to lower malting losses. Gibbing is often practiced in the production of malt for use with mash bills that are mostly comprised of non-malted cereals, such as corn, wheat, and/or rye (e.g., in American bourbon and rye whisky and in scotch and Irish grain whisky; additives, including GA, are prohibited in malt production for scotch whisky). The increased levels of starch-degrading enzymes are desired, as they are absent in non-malted grains.

See also malting.

Briggs, D. E., J. S. Hough, R. Stevens, and T. W. Young. “The Biochemistry of Malting Grain.” In Malting and Brewing Science, vol. 1, Malt and Sweet Wort, 2d ed., 57–107. Kluwer Academic / Plenum, 1981.

Dolan, Timothy C. S. “Malt Whiskies: Raw Materials and Processing.” In Whisky Technology, Production, and Marketing, ed. Inge Russell, Charlie Bamforth, and Graham Stewart, 44–55. San Diego, CA: Elsevier, 2003.

Gupta, Ramwant, and S. K. Chakrabarty. “Gibberellic Acid in Plant: Still a Mystery Unresolved.” Plant Signaling and Behavior 8, no. 9 (2013): E25504-1-25504-5.

By: Elizabeth RhoadesSee kernel.See also malting.