Determination of Fatty Acid Hydroperoxides Produced During the Production of Wort

Kobayashi, Naoyuki; Kaneda, Hirotaka; Kano, Yasunobu; Koshino, Shouhei

doi:10.1002/j.2050-0416.1993.tb01156.x

Cited by 22 publications

(12 citation statements)

References 8 publications

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“…Most residual activity was represented by the LOX 1 isoenzyme which mainly produced the 9-hydroperoxide, precursor of trans 2 nonenal in beer. This supported the hypothesis of Kobayashi et al (1993a) who presented LOX as the main factor involved in off flavor production.…”

Section: Some Kinetic Properties Of Lox 1 and Loxsupporting

confidence: 89%

Two Lipoxygenases from Germinated Barley‐Heat and Kilning Stability

Hugues

Boivin

Gauillard

et al. 1994

Journal of Food Science

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Using ammonium sulfate precipitation followed by hydrophobic and ion exchange chromatography, two lipoxygenase isoenzymes, LOX 1 and LOX 2, were l&3-and 445fold purified from germinated barley, with 18 and 24% recovery of activity respectively. LOX 1 and LOX 2 were characterized by isoelectric points 4.9 and 6.4, and molecular weights of 90 kd and 110 kd, respectively. Apparent Km values for linoleic acid were 0.06 mM for LOX 1 and 0.18 mM for LOX 2. LOX 1 converted linoleic acid to 9 and 13 hydroperoxides at about 4:1, whereas the 13 hydroperoxide was the major product formed by LOX 2 (ratio 3:7). For both isoforms, thermal inactivation data indicated first order kinetics with activation energies influenced by ionic strength and pH. Isoenzymes composition was analyzed for three kilning schemes: the 1:3 ratio between LOX 1 and LOX 2 observed in germinated barley increased during the course of kilning.

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Section: Some Kinetic Properties Of Lox 1 and Loxsupporting

confidence: 89%

Two Lipoxygenases from Germinated Barley‐Heat and Kilning Stability

Hugues

Boivin

Gauillard

et al. 1994

Journal of Food Science

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“…13), nonetheless we were confident in our ability to measure 10-20 nmol of hydroperoxide. This compares favourably with chromatographic methods described by others 24 . In control mashes to which cumene hydroperoxide was added, we were unable to recover the addition in the wort.…”

Section: ]Hvstivs\mhiwsupporting

confidence: 78%

“…Because we were unable to recover added hydroperoxide we are not in a position to say whether hydroperoxides are, or are not, produced during mashing of these malts under the conditions studied. However Kobayashi et al 24 found that hydroperoxides did decrease in level during mashing and wort separation.…”

Section: ]Hvstivs\mhiwmentioning

confidence: 97%

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

Stephenson

Biawa

Miracle

et al. 2003

Journal of the Institute of Brewing

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An assessment of the impact of oxygen and hydrogen peroxide on mashing and wort parameters has been made on a laboratory scale. Oxygen has been stridently eliminated by using an anaerobic chamber during mash analysis. Additionally the relative importance of proanthocyanidin species has been assessed by comparing the behaviour of "conventional" malt and a malt produced from a low proanthocyanidin variety. It seems that oxygen and peroxide act independently in causing the oxidation of thiolcontaining materials and polyphenols in mashes and that oxygen is not primarily exerting its impacts through the intermediacy of peroxide. The removal of thiols (presumably at least in part through the production of disulphide bridges between proteins) and of polyphenols (presumably via polymerisation) both contribute to increased wort turbidity and decreased rates of wort separation after mashing. Three inhibitors (nordihydroguaiaretic acid, ethylenediamenetetraacetate and potassium cyanide) have been employed in an attempt to differentiate between enzymic and non-enzymic events and also to identify whether lipoxygenase and peroxidase are catalysing key events. Whilst it seems that peroxidase has a key role in catalysing the oxidation of polyphenols by H 2 O 2 , it does not appear that either peroxidase or lipoxygenase is involved in the removal of measurable thiol. Nonetheless a significant proportion of the thiol elimination is likely enzyme-catalysed. We have been unable to demonstrate the production of hydroperoxides in mashes, but added hydroperoxide is undetectable, which suggests that these materials are either lost by onward conversion or by adsorption onto spent grains.

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“…At the time of sampling, the entire mash was poured into a beaker with addition of ice-cold distilled water (200 ml) and solid CO, (5 g). The mixture was extracted with diethyl ether/light petroleum (bp 40-60°C) 1 : 1, v/v; 500 ml: Kobayashi et al 1993a). Solvent was removed under reduced pressure from a portion (200 ml) of the extract which was then dissolved in methanol/chloroform (8 : 2, v/v; 10 ml) before analysis by CL-HPLC.…”

Section: Extraction Of Fatty Acid Hydroperoxides From Laboratory-scalmentioning

confidence: 99%

Use of ChemiluminescenceHPLC for Measurement of Positional Isomers of Hydroperoxy Fatty Acids in Malting and the Protein Rest Stage of Mashing

Walker¹,

Hughes²,

Simpson³

1996

J. Sci. Food Agric.

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Fatty acid hydroperoxides (9‐ and 13‐hydroperoxides of linoleic acid and linolenic acid) were extracted from barley, malt and wort, and quantified by chemiluminescence HPLC. Although not detected in dried barley (<0·5 μmol kg−1 (dry wt)), the concentrations of hydroperoxides increased during germination (up to 156 μmol kg−1 (dry wt) in the case of 9‐hydroperoxylinoleic acid). Lipoxygenase (LOX) activity increased more than two‐fold during germination. LOX activity and hydroperoxide concentrations were reduced considerably on kilning of malt. During mashing on a laboratory scale, malts with higher total LOX activities produced higher concentrations of hydroperoxides. The concentrations of 9‐hydroperoxides were double those of the 13‐hydroperoxides during malting and up to 10‐fold greater during mashing, indicating a greater activity of LOX‐1 in both processes.

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Determination of Fatty Acid Hydroperoxides Produced During the Production of Wort

Cited by 22 publications

References 8 publications

Two Lipoxygenases from Germinated Barley‐Heat and Kilning Stability

Two Lipoxygenases from Germinated Barley‐Heat and Kilning Stability

Laboratory-Scale Studies of the Impact of Oxygen on Mashing

Use of ChemiluminescenceHPLC for Measurement of Positional Isomers of Hydroperoxy Fatty Acids in Malting and the Protein Rest Stage of Mashing

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