Color and molecular structure alterations of brazilein extracted from Caesalpinia sappan L. under different pH and heating conditions
Bibliographic record
Abstract
Brazilein extract from sappan wood (Caesalpinia sappan L.) has potential for use as natural food colorant since it has no unique flavor and taste. Although brazilein has long been applied in several traditional foods and beverages, information on its stability, which is of importance for practical application, is still limited. In this work, brazilein was isolated from sappan wood; its purity was confirmed by nuclear magnetic resonance spectroscopy. Relations between molecular structures and color as well as thermal stabilities of brazilein in aqueous solutions at pH 3, 7 and 9 were for the first time investigated. At the lowest pH, zero net-charge structure of brazilein, which exhibited yellow color, was predominantly found. The deprotonated and fully deprotonated structures of brazilein, which exhibited orange and red colors, respectively, were found when pH of the aqueous solutions increased. The forms of brazilein existing at the higher pH suffered extensive degradation upon heating, while the form existing at the lowest pH possessed higher stability. Heat-induced deprotonation and degradation were confirmed by UV-visible and Fourier-transform infrared spectra as well as losses of brazilein content.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".