MBAA TQ https://doi.org/10.1094/TQ-59-2-0609-01 | VIEW ARTICLE
Xiang S. Yin. Rahr Technical Center, Rahr Corporation, MN, USA
Out of a number of leading mechanisms of the formation of staling compounds (carbonyls, ketones, and aldehydes), several initiate from the precursors and enzymes that are presented by malt. Well-known examples are the lipoxygenase (LOX)-mediated oxidation of unsaturated fatty acids, Maillard reaction from thermal load, and Strecker degradation of amino acids. These mechanisms result in staling in all beers but are perceived to varying degrees in different styles of beers as they age. Selected observations from the published literature, as well as supporting data from the author’s research, are presented in this review to demonstrate how malt quality and malting process parameters potentially generate the conditions required for the formation and control of staling compounds in beer. Relevant data supporting the hypotheses include analytical information obtained from assessments, including measurement of malt LOX, thiobarbituric acid index (TBI), free-radical levels in T120 or T150 through electron paramagnetic resonance (EPR), amino acids, and aldehydes, in addition to other malt analyses and sensory tests. Side effects of mitigation and balancing acts for managing malting to improve flavor stability of consequent beers are also discussed.