Reversibility of lychee pericarp red color in relation to pericarp pH, activity of polyphenol oxidase, and particle size of brown pigment
| Autor: | C. L. George Chu, S. K. Eric Leung, Masahiro Kawaji |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
ROUGE
biology food and beverages Horticulture Sapindaceae biology.organism_classification Polyphenol oxidase Red Color chemistry.chemical_compound Pigment chemistry Anthocyanin visual_art Botany Browning biology.protein visual_art.visual_art_medium sense organs Catechol oxidase Agronomy and Crop Science Food Science |
| Zdroj: | Fruits. 59:17-23 |
| ISSN: | 1625-967X 0248-1294 |
| DOI: | 10.1051/fruits:2004002 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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