Reversibility of lychee pericarp red color in relation to pericarp pH, activity of polyphenol oxidase, and particle size of brown pigment
Bibliographic record
Abstract
Fruits, vol. 59 (1) 17Reversibility of lychee pericarp red color in relation to pericarp pH, activity of polyphenol oxidase, and particle size of brown pigment. Abstract --Introduction.The peel of lychee fruit turns from its attractive bright red color to a dull brown color when the fruit starts to age.This study reports how the color change of lychee pericarp from red to brown is associated with several factors and may be reversed depending on its pH, anthocyanin content and brown pigments.Materials and methods.After transport by air transit from China to Canada, arriving 4 d after harvest, the anthocyanin, brown pigment concentrations and the pH values in the lychee (Litchi chinensis Sonn.) pericarp were determined over a period of 5 d at 25 °C and 65% RH.The macromolecular sizes of the brown pigment extract were measured in solutions between a pH of 4 and 6. Results and discussion.The acidity in the lychee pericarp decreased from a pH of 4.3 to 5.3, at the end of the 5-day period.The anthocyanins in the lychee pericarp decreased and the brown pigment increased.Polyphenol oxidase in the pericarp was active when its pH was between 4.1 and 4.6, and became less active when its pH was above 4.6.The diameter of the brown pigment molecules in the solutions increased when the pH of the solutions was increased and maintained for 5 d.The anthocyanins returned to their original redness and concentrations if they were placed in solutions with a pH value ranging between 4 and 6 for 10 min or they were placed in solutions with a pH value of 4 for 5 d.However, the anthocyanins did not return to their original redness and concentration if they were placed in solutions with a pH value ranging between 5 and 6 for 5 d. Conclusion.This study suggests that the bright red color of lychee peel could be maintained if its pericarp pH could be maintained at a pH of 4. If the pericarp pH is above 4, the reversibility of its bright red color from brown pigments is dependent on storage time. Canada / Litchi chinensis / fruits / coloration / pigments / anthocyanins / browningRéversibilité de la couleur rouge du péricarpe de litchi en fonction du pH, de l'activité polyphénol oxydase et de la taille des particules de pigments bruns.Résumé --Introduction.La peau du litchi tourne d'une belle couleur rouge vif à une couleur brune mate quand le fruit commence à vieillir.Notre étude montre que, dans le péricarpe de litchi, le changement de couleur du rouge au brun est associé à plusieurs facteurs et qu'il peut être réversible selon le pH et la teneur en anthocyanes et en pigments bruns de l'écorce du fruit. Matériel et méthode.Quatre jours après la récolte du fruit transporté par avion de Chine au Canada, les concentrations en anthocyanes et en pigments bruns et les valeurs de pH du péricarpe de litchis (Litchi chinensis Sonn.) entreposés à 25 °C et 65% d'humidité relative ont été suivies pendant 5 j.La taille macromoléculaire des pigments bruns ont été mesurées dans des solutions de pH 4 à 6. Résultats et discussion.En 5 j de stockage, le pH dans le péricarpe de litchi a diminué de 4,3 à 5,3.Dans le même temps, les anthocyanes ont diminué et la teneur en pigments bruns a augmenté.La polyphénol oxydase du péricarpe a été active pour un pH compris entre 4,1 et 4,6 et elle est devenue moins active lorsque le pH de l'épicarpe a dépassé la valeur de 4,6.Le diamètre des molécules de pigments bruns des extraits analysés a augmenté quand le pH des solutions augmentait et était maintenu pendant 5 j.Les anthocyanes ont récupéré leur couleur rouge et leur concentration initiale lorsqu'elles ont été placées dans des solutions avec un pH s'échelonnant de 4 à 6 pendant 10 min, ou avec un pH de 4 pendant 5 j.Ce même phénomène n'a pas été observé en solutions maintenues à pH 5 ou 6 pendant 5 j. Conclusion.Cette étude suggère que la couleur rouge vif de la peau de litchi pourrait être conservée si le pH de son péricarpe pouvait être maintenu à 4. Au-dessus de cette valeur, la réversibilité de la couleur rouge à partir des pigments bruns dépend du temps d'entreposage. Canada / Litchi chinensis / fruits / coloration / pigment / anthocyane / brunissement
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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 | 0.001 |
| 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".