Development of stable isotope dilution assays for the quantitation of free phenolic acids in wheat and barley and malts produced thereof

Langos, Daniel; Granvogl, Michael; Meitinger, Michael; Schieberle, Peter

doi:10.1007/s00217-015-2492-0

Cited by 9 publications

(16 citation statements)

References 29 publications

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“…Furthermore, phenolic acids were mainly determined by HPLC in combination with a diode array detector, ,,,,,, a CoulArray detector, , or a mass selective detector. , However, validation of the extraction efficiency of the methods was scarcely performed. Addressing this deficiency, Langos et al studied the impact of different solvents and extraction times on the extraction efficiency of phenolic acids, showing that the use of pure water was insufficient, most likely due to the still active enzymes during extraction. In contrast, methanol, with its ability to inactivate enzymes, was proven to be the best extraction solvent.…”

Section: Resultsmentioning

confidence: 99%

“…According to the preserved enzyme activity after malting, a further breakdown with a further release of the different phenolic acid forms can be assumed during mashing. Up to now, studies investigating the coherence between vinyl aromatics and their precursors in wheat beer have only been focused on the free form of phenolic acids. − ,− However, no correlation was found between the free precursor concentrations in any of the processing steps of wheat beer production compared to the final vinyl aromatic concentrations in wheat beer. , The reason therefore is given by the fact that the feruloyl esterase is still active after kiln-drying and that yeast has its own feruloyl esterase . Therefore, the parameter of interest is the sum of soluble phenolic acids, which can be transferred into wort, rather than only the free form.…”

Section: Resultsmentioning

confidence: 99%

“…Barley varieties used in this study were Catamaran (spring barley (sp), two-rowed (2r), Franconia, Germany), Solist (sp, 2r, Franconia), Quench (sp, 2r, Denmark), and Liga (winter barley, 2r, Franconia); wheat varieties were Elixer (Upper Palatinate, Germany), Pannonia (Czech Republic), and Torp (Denmark); all harvested in 2017. Malting conditions were as follows: grain was steeped for 4 h at 16 °C in a physiological saline solution (0.9%), followed by a 20 h air rest (25 L/min, 80% humidity). This cycle was repeated with an additional 3 h wet stand and a 21 h air rest.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…As a consequence, mitigation strategies had to be developed for foods containing styrene. Schwarz et al − and Langos et al ,− investigated the impact of the different processing steps of wheat beer, focusing on the release of undesired styrene, and also on the desired aroma-active vinyl aromatics. It is known that all of these compounds are mostly formed during the fermentation step, whereas thermal processing steps, such as mashing, wort boiling, and flash pasteurization, had a negligible effect on their concentrations .…”

Section: Introductionmentioning

confidence: 99%

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Studies on the Impact of Malting and Mashing on the Free, Soluble Ester-Bound, and Insoluble Ester-Bound Forms of Desired and Undesired Phenolic Acids Aiming at Styrene Mitigation during Wheat Beer Brewing

Kalb

Seewald

Hofmann

et al. 2020

J. Agric. Food Chem.

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Mitigation studies on styrene in wheat beer found no correlation between the free phenolic acid contents in the processing steps and the final concentrations of the toxicologically relevant styrene and the desired aroma-active vinyl aromatics in beer, which can be explained by the presence of phenolic acid releasing enzymes that are still active after kiln-drying and by the yeast′s own feruloyl esterase activity. The present study contributed to a better understanding of the coherence between the free, soluble ester-bound, and insoluble ester-bound forms of cinnamic, p-coumaric, and ferulic acid during malting and mashing of barley and wheat varieties. Concentration differences in malt by factors of up to 1700 were found between the total cinnamic acid contents (an undesired precursor of the toxicologically relevant styrene) and the total contents of p-coumaric and ferulic acid (both desired precursors of the aroma-active compounds 4-vinylphenol and 2-methoxy-4-vinylphenol). In grain and malt, cinnamic acid occurred predominantly in a soluble form, whereas the desired precursors were mainly insoluble ester-bound. This had a direct effect on the transfer rates from malt into wort, which were found to be >100% for cinnamic acid, revealing that a complete transfer was accompanied by an additional biosynthesis, but only <8% for the desired phenolic acids. Interestingly, in the wort, cinnamic and pcoumaric acid contents were dominated by the free form, while ferulic acid was mostly still soluble ester-bound. Overall, the use of barley malts led to an introduction of cinnamic, p-coumaric, and ferulic acid into the wort in a ratio of 2:14:84, and the use of wheat malt in a ratio of 1:2:97.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Studies on the Impact of Malting and Mashing on the Free, Soluble Ester-Bound, and Insoluble Ester-Bound Forms of Desired and Undesired Phenolic Acids Aiming at Styrene Mitigation during Wheat Beer Brewing

Kalb

Seewald

Hofmann

et al. 2020

J. Agric. Food Chem.

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“…Also, green malt had high antioxidant activity. According to study of Langos et al (2015), the content of ferulic, pcoumaric and caffeic acids in mg/kg were 0.59 in barley, 2.76 in green malt and 3.37 in dried malt; 0.28 in barley, 1.31 in green malt and 0.98 in dried malt; 0.42 in barley, under the LOD value in green malt and dried malt, respectively. Results showed some differences compared to literature.…”

Section: Resultsmentioning

confidence: 99%

Effect of malt process steps on bioactive properties and fatty acid composition of barley, green malt and malt grains

Özcan¹,

Juhaimi²,

Uslu³

2017

J Food Sci Technol

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In this study, the effect of barley malt process on antioxidant activity, carotenoid content, oil yield, phenolic compounds and fatty acid composition of barley, green malt and malt was investigated. The highest antioxidant activity (79.80%) and total phenolic content (122.43 mg/100 g) was observed in green malt. Carotenoid content of green malt (1.71 µg/g) was higher than those of barley and malt. Green malt had the maximum (+)-catechin (69.06 mg/100 g), 1,2-dihydroxybenzene (37.21 mg/100 g), quercetin (30.78 mg/100 g) and isorhamnetin (22.44 mg/100 g) content. Oil contents of samples ranged from 1.73 to 2.13% and showed increase with malting process. While barley lipids contained 18.53% palmitic, 19.94% oleic and 51.74% linoleic acids, malt oil contained 17.33% palmitic, 15.62% oleic and 56.56% linoleic acids. Linoleic acid content increased during malting process while oleic and palmitic acid content decreased.

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The impact of caramel and roasted wheat malts on aroma compounds in top‐fermented wheat beer

Reglitz

Féchir

Voigt

et al. 2022

J Institute Brewing

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Top-fermented wheat beers are known for their unique aroma. However, the impact of speciality wheat malts on the aroma of these beers and the transfer of odour active compounds from malt to the beer has not been investigated in detail. Three beers were brewed with different malt composition. The grist for each beer contained 50% kilned barley malt and 50% different wheat malts -beer (1) kilned wheat malt, beer (2) kilned wheat malt and caramel wheat malt, and beer (3) kilned wheat malt and roasted wheat malt. The odour active compounds in the beers were identified by aroma extract dilution analysis and their individual impact on aroma was evaluated by quantitation and calculation of odour activity values (OAVs). The results were verified sensorially by comparing aroma reconstitution models with the original beers. Characteristic odour active compounds in the beer brewed with caramel wheat malt were earthy compounds 2-ethyl-3,5-dimethylpyrazine, 2-ethyl-3,6-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, caramel-like compounds 4-hydroxy-2,5-dimethylfuran-3(2H)-one and maltol, and sotolon with a soup seasoning-like aroma. The aroma of the roasted wheat malt beer was characterised by smoky and phenolic compounds 2-methoxyphenol and 4-methylphenol. Important beer odorants were quantified in the malts to assess their transfer from malt to beer. The results suggest that direct transfer of the odour active compounds in beers was not significant and that they were formed and/or released during the brewing process, confirming earlier results with different barley malts and bottom-fermented beers.

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Development of stable isotope dilution assays for the quantitation of free phenolic acids in wheat and barley and malts produced thereof

Cited by 9 publications

References 29 publications

Studies on the Impact of Malting and Mashing on the Free, Soluble Ester-Bound, and Insoluble Ester-Bound Forms of Desired and Undesired Phenolic Acids Aiming at Styrene Mitigation during Wheat Beer Brewing

Studies on the Impact of Malting and Mashing on the Free, Soluble Ester-Bound, and Insoluble Ester-Bound Forms of Desired and Undesired Phenolic Acids Aiming at Styrene Mitigation during Wheat Beer Brewing

Effect of malt process steps on bioactive properties and fatty acid composition of barley, green malt and malt grains

The impact of caramel and roasted wheat malts on aroma compounds in top‐fermented wheat beer

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