Influence of the Malt Variety on Lipoxygenase

Influence of the malt variety on the LOX-activity and potential

Table of contents

List of Abbreviations II

List of tables and equations III

Table of Figures IV

1 Introduction 1

2 The Lipoxygenase 2

3 Flavor active compounds formation 4

4 LOX activity & potential 5

5 Influence of barley variety and cultivation area on LOX-activity 6

6 Influence of malting and malt type on LOX activity & potential 7

7 Screenings and studies of LOX-less and LOX-free barley 8

8 Summary 10

9 Bibliography 11

10 Attachments 14

List of Abbreviations

e.g for example

LOX Lipoxygenase

LOX-1 Lipoxygenase-1

LOX-2 Lipoxygenase-2

PUFA polyunsaturated fatty acids

LA linoleic acid

LeA linolenic acid

9-HPOTE 9-hydroperoxide-octadecadienoic acid

13-HPOTE 13-hydroperoxide-octadecadienoic acid

HPOD Hydroxyperoxide

THOD Trihydroxyoctadenoic acid

T2N trans-2-nonenal or (E)-2-nonenal

List of tables and equations

Equation 1: Volumetric activity 5

Equation 2: Specific activity 5

Equation 3: LOX-Potential 5

Table of Figures

Figure 1: Oxidation of linoleic acid by LOX-1 & LOX-2 to 13- & 9-hydroperoxyde 2

Figure 2: A. & B. LOX-1 and 2 expression and formation of their products throughout germination …………………………………………………………………………..……….. 3

Figure 3: A. & B. LOX-activity and potential of raw extract and gel fraction differing in barely varieties an growing areas …………………………………………………………....6

Figure 4: Effect of addition of 10% (w/w) caramel and 2% (w/w) black speciality malts on lipoxygenase activity of pale malt during mashing……………………………………..8

Figure 5: A. & B. Amount of T2N formed when using either a normal barley

Bibliography: “Molecular characterization of two lipoxygenases from barley” Plant Molecular Biology, 39: 1283–1298, 1999 “Expression of lipoxygenase isoenzymes in developing barley grains” Plant Science, 128: 141–150, 1997 6. Doderer, A., Kokkelink, I., van der Veen, S., Valk, B., Schram, A. and Douma, A “Purification and characterization of two lipoxygenase isoenzymes from germinating barley” Biochimica et Biophysica Acta, 1211: 97-104, 1992 Journal of Food and Agricultural Chem., 53: 1556-1562, 2005 8 “Lipoxygenase activity, regermination ability and hydroxylated fatty acids in the mash” Brauwelt International, 142: 28-34, 2005 “The Production of Linoleic and Linolenic Acid Hydroperoxides during Mashing” Journal of fermentation and bioengineering, Vol. 76, No. 5: 371-375, 1993 11 “Der Einfluss des Blattkeims von Gerstenmalz auf die Geschmacksstabilität und weitere Qualitätsmerkmale von Bier” Dissertation, TU München, 2003 “Influence of malt browning degree on lipoxygenase activity” Food Chemistry, 99: 711-717, 2006 “Anbau eine LOX-freien Braugerste ab 2008“ Brauwelt, 147: 747, 2007