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O-13. Malting process optimization of barley (Hordeum vulgare L.) to reduce the content of initiators and maximize the content of inhibitors of sunstruck flavor.

Presenter: Alicia Muñoz Insa, TUMünchen, Lehrstuhl für Brau- und Getränketechnologie, Freising, Germany. Coauthor(s): Martina Gastl, TUMünchen, Lehrstuhl für Brau- und Getränketechnologie, Freising, Germany; Thomas Becker, Technische Universität München Weihenstephan, Freising, Germany.

Sunstruck flavor is an off-flavor formed by exposure to light during storage of beer. Isohumulone, present in hops, is the main substrate of this reaction, but other substances present in malt also play an important role. Substances such as riboflavin, cysteine, and methionine are known as off-flavor initiators and tryptophan and polyphenols as off-flavor inhibitors. In this work, the malting process of barley was optimized to ensure good processability and also to maximize the content of inhibitors and minimize the content of initiators of sunstruck flavor. Minimizing or maximizing the content of initiators or inhibitors, respectively, present in malt makes it possible to reduce the off-flavor in the final beer or beverage. The influence of three malting parameters (degree of steeping, germination time, and germination temperature) on the quality of barley malt was investigated. A series of malt quality parameters was evaluated to examine and guarantee good processability: extract, apparent attenuation limit, Kolbach index, free amino nitrogen, β-glucan, and viscosity. Also, the content of inhibitors and initiators of sunstruck flavor in malt was analyzed.

Alicia Muñoz Insa was born in 1983 in Spain. She graduated with a Dipl. Ing. degree at the Universidad Politécnica de Madrid in 2009 and carried out her diploma thesis research at TU München. Since 2009 she has been a Ph.D. student at the Lehrstuhl für Brau- und Getränketechnologie, TUM, working in the field of beverages of alternative cereals.