Kinetic modelling of blueberry anthocyanins oxidation with a free radical initiator 2,2'‐azobis(2‐amidinopropane)
Bibliographic record
Abstract
ABSTRACT The antioxidant activity of the main anthocyanin isomers isolated from wild blueberries of Lake Saint‐Jean (Quebec, Canada), the galactoside and glucoside isomers of cyanidine, peonidine, and malvidine, were studied through identification and quantification of oxidation products by liquid chromatographic analysis coupled to mass spectrometry. A simplified lumped kinetic model was developed taking into account the essentially radical nature of anthocyanin oxidation by AAPH (2,2′‐azobis(2‐amidinopropane) dihydrochloride) radicals through a scavenging mechanism. The calculated pseudo‐first order kinetic profiles of anthocyanins and the oxidation product common to all anthocyanins, 3,5‐dihydroxy‐4‐(ethen‐1,1‐diol) phenol derivative (fragment m/z 184), together with the specific oxidized product exclusive to the anthocyanidin nature, p‐hydroxybenzoic acid derivative (fragment m/z 154), appropriately fit experimental data at AAPH concentrations of 43.7 and 25.5 μmol/mL. It is shown that galactoside‐bonded peonidin (0.057 h−1) was more reactive than glucoside‐bonded peonidin (0.013 h−1) to generate the common oxidized product. An opposite tendency was observed when the reactivities of galactoside‐bonded cyanidin (0.026 h−1) and glucoside‐bonded cyanidin (0.085 h−1) were compared for an AAPH concentration of 43.7 μmol/mL. Malvidin‐3‐glucoside reacted weakly with AAPH radicals compared to the peonidin and cyanidin‐counterparts. These results suggested that anthocyanin reactivity towards AAPH‐radicals was associated not only with the anthocyanidin structure, but also with sugar moiety and the kinetics of peroxyl radical formation. The kinetic constants of anthocyanin oxidation product formation can be related to the oxygen radical absorbance capacity (ORAC) and then used to evaluate antioxidant properties.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".