Influence of Malt Roasting on the Oxidative Stability of Sweet Wort

Hoff, Signe; Lund, Marianne N.; Petersen, Mikael Agerlin; Jespersen, Birthe Møller; Andersen, Mogens L.

doi:10.1021/jf300749r

Cited by 36 publications

(48 citation statements)

References 26 publications

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“…The colour of wort made from pilsner malt was not affected by storage time and conditions. The pH of the worts was constant throughout the experiment, and generally the pH of the pilsner wort was approximately one unit higher than that of the wort made from roasted malt, in line with previous findings . The sugar content was also constant throughout the 12 months of storage for both types of worts.…”

Section: Resultssupporting

confidence: 89%

“…Selected volatiles were studied in relation to storage and it was observed that Strecker aldehydes and N ‐heterocyclic compounds increased slightly in concentration within the first few months and then decreased to concentrations below the initial content, and interestingly similar variations in malt and beer aromas were identified . In a recent study it was found that sweet worts made from roasted malts with colours above 33 EBC units were very susceptible to a loss of volatiles when exposed to mild heating, whereas the profile of volatile compounds of wort made from pilsner malt was not affected by the heating .…”

Section: Introductionmentioning

confidence: 99%

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Quality of pilsner malt and roasted malt during storage

et al. 2014

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Malt is usually expected to be stable during 12 months of storage. However, in practice many brewers notice changes in malt aroma during storage. The oxidative stabilities of pilsner malt and roasted malt were evaluated during a 12 month storage at different temperatures (10 and 20°C) and water activities (0.231 and 0.432). The radical content in malt kernels was measured by electron spin resonance spectroscopy and the volatile profile of the resulting sweet worts was measured by head-space analysis followed by GC-MS analysis. The storage of malt resulted in oxidative reactions and a large change of the volatile profile of the resulting worts. Roasted malt was much more unstable than pilsner malt, as illustrated by a higher initial radical intensity, larger radical decay during storage and a larger change in the volatile profile of the wort with increased amounts of lipid oxidation products. For both roasted malt and pilsner malt, good correlations were found between radical decay and changes in the volatile profile of the wort, where high temperature and high water activity resulted in the largest changes. During the 12 months of storage, the sugar extract of the wort made from the malts remained constant and was not affected by the chemical changes. This study suggests that chemical changes occurring in malts during less than 12 months of storage may potentially affect the aroma of beer, and that water activity and storage temperature should both be kept low in order to maintain a high malt quality.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Quality of pilsner malt and roasted malt during storage

et al. 2014

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“…The increasing intensity of the pink colour suggests an increase of hydroperoxide groups in malts kilned to a higher degree. This data is supported by current research that shows an increase in organic radicals and a decrease in oxidative stability in worts produced by dark specialty malts .…”

Section: Resultssupporting

confidence: 83%

Foam inhibitors from specialty malts

Ang

Bamforth

2014

J. Inst. Brew.

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Although there are product to product differences, the majority of the crystal and caramel malts tested have been shown to have a net destabilizing impact on foam. A foaming test using a model beer has been developed to quantify the magnitude of this inhibitory effect. Lipid analysis using thin layer chromatography reveals that there are elevated levels of triglycerides in problematic malts. There also appear to be oxidized lipids in the specialty malts, likely produced in the heating stage of malt production with higher levels in more intensely heated products. However some specialty malts, such as black malt, whilst containing such foam-negative entities, do display superior foaming properties, probably because they develop even more powerful foam-positive components in the severe heating events.

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“…The sample of boiled wort was collected after 30 min of boiling, immediately before hops were added, and the sample of hopped boiled wort was collected after 90 min of boiling, immediately before cooling. Sweet wort was found to have the lowest radical forming intensity compared with boiled wort and hopped boiled wort in line with previous studies (6,17).…”

Section: Wort and Beersupporting

confidence: 90%

Storage stability of pasteurized non-filtered beer

et al. 2013

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The influence of pasteurization on non-filtered beers was investigated during accelerated storage (40°C, 41 days). Two beers were produced from the same hopped wort, which was fermented with two different yeast strains. Half of the bottled beers were tunnel pasteurized resulting in four different beer samples. The pasteurization influenced the volatile profile of both fresh beers, but during storage the differences between the volatile profiles of pasteurized and non-pasteurized beers disappeared. During the storage period, the pasteurized beers gave a lower rate of radical formation, as evaluated by electron spin resonance spectroscopy, indicating a better oxidative stability. The pasteurization had no effect on the levels of the pro-oxidative metals iron and copper. Pasteurization slightly increased the protein content of the beers. SDS-PAGE analysis showed that the two beers had different protein profiles, which changed during storage; however, pasteurization of both beers did not affect their protein profiles. The level of thiols were lowered in one beer and raised in the other beer by pasteurization, but during storage the levels of thiols decreased at the same rate in all of the beers. It was concluded that pasteurization had a positive influence on the oxidative stability of non-filtered beer.

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Influence of Malt Roasting on the Oxidative Stability of Sweet Wort

Cited by 36 publications

References 26 publications

Quality of pilsner malt and roasted malt during storage

Quality of pilsner malt and roasted malt during storage

Foam inhibitors from specialty malts

Storage stability of pasteurized non-filtered beer

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