Research On Improving The Flavor Stability Of Beer By Controlling Activity Of LOX In Malt

Lipid oxidation is one of the main causes of beer staling, and lipoxygenase (LOX) participates in lipidoxidation reaction directly. The final metabolite of enzymatic oxidation reaction is Trans-2-Nonanal (T2N),which is a kind of typical aging indicator. T2N presents “cardboard flavor”, and the flavor threshold of T2Nis0.1ppb. T2N is also a typical staling material of beer, which is regarded rice as adjunts. The activity ofLOX in materials or adjunts during beer brewing, and the content of T2N which is generated duringenzymatic oxidation reaction are determinated and analyzed in this article. The relationship between LOXin malt and the beer flavor stability is mainly researched, which provides the theoretical foundation ofkeeping fresh and flavor stability of beer or controlling the staling flavor of beer. The main results areshown below: It can influence the beer flavor stability and has significant negative influence on beerquality. The relationship between LOX in malt and the beer flavor stability is researched in this article.According to the material of beer brewing, the activity of LOX during brewing process is controlled inorder to reach the goal of improving the flavor stability of beer. The main results are shown below: Fordifferent barley varieties, the activity of LOX is changed with different producing year, area and genotypeunder the optimum conditions of measuring method; According to the analyzation of response surfacedesign optimization method, and the optimum malting processes are shown as follows: steeping time is24.0h, germination temperatureis13.9℃, Kilning temperature is89.5℃; After improving the process ofsaccharification, the content of T2NP in wort is reduced16.7%, and the relationship between LOX in maltand T2N in fresh, forcing test beer or sensory evaluation is shown at a fine level. In a word, by studyingcomparatively, the relationship between LOX during the process of production and flavor stability of beeris further confirmed, and on the aspect of keeping fresh flavor of beer is innovated.