The pericarp color, browning-related enzyme activity and variations in phenolic compounds during the browning process of litchi pericarp were evaluated to investigate the alterations in ingredients caused by pericarp browning of two litchi varieties (Guiwei and Yuhebao) during storage. The indicators were comprehensively evaluated using correlation analysis and principal component analysis. The results showed that at a storage temperature of 4 ℃, the pericarp of Yuhebao was more likely to brown than that of Guiwei. After being stored for three days, the pericarp of Yuhebao exhibited noticeable browning, but Guiwei only displayed a similar phenomenon after seven days of storage. Over the period of 0-14 days of storage, both Guiwei and Yuhebao showed a decline in the total phenolic, flavonoid and proanthocyanidin levels in the pericarps due to browning. Both Guiwei and Yuhebao pericarps exhibited an increased trend in pH value, with the lower rise rate in pH value of Guiwei pericarp compared with that of Yuhebao. Additionally, the level of polyphenol oxidase (PPO) activity in the pericarps of both litchis exhibited a declining pattern, with a more pronounced decline observed in Yuhebao compared to Guiwei. The peroxidase (POD) enzyme activity in the two litchi pericarps exhibited a little decline, whereas the POD enzyme activity in the Yuhebao pericarp was approximately 1.33 times higher than that of Guiwei. Correlation analysis and principal component analysis revealed that total phenols, flavonoids, PPO and pH value were found to have a significant correlation with the browning color of the two litchi varieties. There was a noticeable correlation between the selected litchi varieties and the browning process, indicating distinct differences in the browning status of the pericarp. The findings of this study could offer fundamental data support for future research on suppressing the browning phenomena of litchi pericarp, extracting and processing phenolic active compounds from litchi pericarp.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |