Complexation of transition metals by chelators added during mashing and impact on beer stability
| Autor: | Thomas Kunz, Tuur Mertens, Frank-Jürgen Methner, Philip C. Wietstock |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
0106 biological sciences
IONS inductively coupled plasma optical emission spectrometry inductively coupled plasma optical emission spectrometry (ICP-OES) Inorganic chemistry Oxidative beer stability INSTABILITY electron spin resonance (ESR) spectroscopy 01 natural sciences transition metals OXIDATIVE STABILITY HOPPING TECHNOLOGY 0404 agricultural biotechnology electron spin resonance spectroscopy Transition metal Mashing 010608 biotechnology oxidative beer stability WORT Science & Technology Chemistry IRON chelator efficacy food and beverages chelate complexes 04 agricultural and veterinary sciences PHENOLIC-COMPOUNDS ACIDS 040401 food science BITTERNESS CONSISTENCY 540 Chemie und zugeordnete Wissenschaften Food Science & Technology ddc:540 ELECTRON-SPIN-RESONANCE Life Sciences & Biomedicine Food Science |
| Popis: | Beer inevitably changes due to an array of staling reactions. A major factor in beer ageing is the involvement of transition metals (iron, copper, manganese) in oxidative reactions. To tackle the flavour stability issue, metal chelation was investigated. Based on previous research, five primary chelators (tannic acid, gallic acid, EDTA, citric acid and phytic acid) were screened using experimental design for their capacity to reduce the content of wort transition metals. The chelating agents were added under varying conditions (mash out temperature, mash pH, grain bill, chelator concentration, addition time) during laboratory scale mashing to assess how they altered complexation and metal load. Fourteen alternative chelators (ferulic acid, tartaric acid, quercetin, chlorogenic acid and ten polyphenolic food extracts: green tea, pomegranate, grape seed, reishi, cinnamon, curcuma, milk thistle, ginkgo, grapefruit seed and raspberry) were also explored. Metal ions were analysed using inductively coupled plasma optical emission spectrometry and wort oxidative stability by electron spin resonance spectroscopy. Mash pH was the most decisive of all tested process variables: acidified mashing (pH 6 to 5) produced worts with more iron, manganese and zinc (230, 320 and 150%, respectively). Addition of effective chelators counteracted this undesirable effect for iron. Green tea extract, tannic acid and, particularly, pomegranate extract all resulted in lower wort iron. Conversely, addition of EDTA, caused iron, manganese and zinc to increase. Pomegranate extract (90% ellagic acid) was the best performing chelator and reduced radical generation in wort (80% reduction by 60 mg/L addition), making it a promising novel compound in the improvement of beer shelf life. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling. |
| Databáze: | OpenAIRE |
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