Key staling compounds in beer, e.g., ketones and aldehydes, initiate from precursors and enzymes present in malt. Staling mechanisms include lipoxygenase (LOX) mediated oxidation of unsaturated fatty acids, aldehydes originating from process thermal load, and Strecker degradation of amino acids. This presentation gives an overview of how malt quality and malting parameters impact the formation of beer staling compounds through the examination of malt lipoxygenase (LOX), thiobarbituric acid index (TBI), and malt amino acid profiles. Factors shown to influence beer stability include soluble protein, FAN, wort color, barley variety and malt house. While LOX activity is generally recognized as a critical factor in the generation of papery/cardboard notes in light/adjunct beers, Maillard reaction products and Strecker degradation of amino acids appears to be the dominant mechanism of beer staling in all-malt beers. Preventative measures that may improve beer flavor stability are discussed.

Learning Objectives:

• Discuss how malting and malt quality influence staling compounds in beer
• Explain the relationship between FAN and beer stability, especially in all-malt brewing
• Review practical methods to improve beer flavor stability