The formation of diacetyl and acetoin from α‐acetolactic acid

Man, J. C. de

doi:10.1002/recl.19590780703

Cited by 56 publications

(8 citation statements)

References 8 publications

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“…The rate of this decomposition is both pH and temperature dependent, increasing as temperature is raised and pH is lowered . The time required for complete decarboxylation of aqueous acetolactic acid at 20 °C ranges from a few hours at a pH of 1.0 to 2 weeks at a pH of 4.65 . For our reaction conditions that are not buffered or pH adjusted (dependent on pyruvic acid concentration, pH ∼ 2.4 for 10 mM pre-irradiation solutions), it is reasonable to expect that acetolactic acid generated photochemically would be partially decarboxylated, allowing us to observe both acetolactic acid and acetoin during post-irradiation analysis.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

et al. 2017

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The aqueous phase photochemistry of pyruvic acid, an important oxidation product of isoprene, is known to generate larger oligomeric species that may contribute to the formation of secondary organic aerosol in the atmosphere. Using high resolution negative mode electrospray ionization mass spectrometry, the aqueous photochemistry of dilute solutions of pyruvic acid (10, 1, and 0.5 mM) under anaerobic conditions was investigated. Even at the lowest concentration, covalently bonded dimers and trimers of pyruvic acid were observed as photochemical products. We calculate that it is energetically possible to photochemically generate parapyruvic acid, a dimer of pyruvic acid that is known to form via dark oligomerization processes. Subsequent photochemical reactions of parapyruvic acid with pyruvic acid form larger oligomeric products, such as 2,4-dihydroxy-2-methyl-5-oxohexanoic acid. A robust and relatively simple photochemical mechanism is discussed that explains both the conditional dependence and wide array of products that are observed.

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Section: Resultsmentioning

confidence: 99%

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

et al. 2017

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“…The background enzyme activity observed in the control MGA3 pBV2xp strain is most probably due to spontaneous decarboxylation of acetolactate, that accumulates due to activity of native acetolactate synthase encoded by ilvH and ilvB, to acetoin. 53 Overexpression of alsSD operons derived from B. subtilis and B. licheniformis led to enzyme activity at levels of 11.3 ± 2.3 and 4.8 ± 1.7 U/mg, respectively.…”

Section: Heterologous Expression Of α-Acetolactate Synthase and α-Acetolactate Decarboxylase And Production Of Acetoin In B Methanolicusmentioning

confidence: 96%

Methanol-based acetoin production by genetically engineeredBacillus methanolicus

et al. 2020

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“…lactis biovar diacetylactis , Leuconostoc spp. [4] and various Lactobacillus spp. [5, 6] are able to generate diacetyl, or more precisely its precursor α-acetolactate, when citric acid is present.…”

Section: Introductionmentioning

confidence: 99%

“…1). α-Acetolactate, the intermediate in this pathway, is inherently unstable and can either be enzymatically converted into acetoin or undergo spontaneous decarboxylation to diacetyl under aerobic condition [4, 8–11]. As a result, α-acetolactate is mainly transformed into acetoin.…”

Section: Introductionmentioning

confidence: 99%

“…However, small amounts of diacetyl can also form when oxygen is present. It has been found that the presence of metal ions accelerate the chemical conversion of α-acetolactate into diacetyl, which can be used for industrial diacetyl production [4, 12]. Even though diacetyl is a very potent flavor molecule there are some advantages of using α-acetolactate instead, since diacetyl is highly volatile, which complicates its use in food products.…”

Section: Introductionmentioning

confidence: 99%

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Efficient production of α-acetolactate by whole cell catalytic transformation of fermentation-derived pyruvate

et al. 2019

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BackgroundDiacetyl provides the buttery aroma in products such as butter and margarine. It can be made via a harsh set of chemical reactions from sugarcane bagasse, however, in dairy products it is normally formed spontaneously from α-acetolactate, a compound generated by selected lactic acid bacteria in the starter culture used. Due to its bacteriostatic properties, it is difficult to achieve high levels of diacetyl by fermentation. Here we present a novel strategy for producing diacetyl based on whole-cell catalysis, which bypasses the toxic effects of diacetyl.ResultsBy expressing a robust α-acetolactate synthase (ALS) in a metabolically optimized Lactococcus lactis strain we obtained a whole-cell biocatalyst that efficiently converted pyruvate into α-acetolactate. After process optimization, we achieved a titer for α-acetolactate of 172 ± 2 mM. Subsequently we used a two-stage production setup, where pyruvate was produced by an engineered L. lactis strain and subsequently used as the substrate for the biocatalyst. Using this approach, 122 ± 5 mM and 113 ± 3 mM α-acetolactate could be made from glucose or lactose in dairy waste, respectively. The whole-cell biocatalyst was robust and fully active in crude fermentation broth containing pyruvate.ConclusionsAn efficient approach for converting sugar into α-acetolactate, via pyruvate, was developed and tested successfully. Due to the anaerobic conditions used for the biotransformation, little diacetyl was generated, and this allowed for efficient biotransformation of pyruvate into α-acetolactate, with the highest titers reported to date. The use of a two-step procedure for producing α-acetolactate, where non-toxic pyruvate first is formed, and subsequently converted into α-acetolactate, also simplified the process optimization. We conclude that whole cell catalysis is suitable for converting lactose in dairy waste into α-acetolactate, which favors resource utilization.

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The formation of diacetyl and acetoin from α‐acetolactic acid

Cited by 56 publications

References 8 publications

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

Methanol-based acetoin production by genetically engineeredBacillus methanolicus

Efficient production of α-acetolactate by whole cell catalytic transformation of fermentation-derived pyruvate

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