Isolation and antioxidant activity of protein-polysaccharide complex from dried longan pulp

The objective of this study was to evaluate the antioxidant ability in vitro of the protein-polysaccharide complex extract from longan after the drying.
The dried longan pulp at a certain ratio of solid to liquid (1/25, W/W), was stirred with hot water at 50°C for 3 h at pH 6, leached, concentrated, centrifuged, dialyzed, and freeze-dried to obtain dried longan pulp protein-polysaccharide complex (LDC). The antioxidant activities of LDC were evaluated by ferric ion reducing antioxidant power (FRAP), total reducing power and ABTS^•+ clearance rate.
The results showed that the LDC had obvious capability of reducing Fe³⁺, total reducing power and ABTS^•+ scavenging capacity, and had a significant positive correlation with its concentration.
At a concentration of 5 mg mL^‑1, the LDC of dried longan pulp obtained the highest FRAP value (0.71±0.02 mmol L^‑1), while at a concentration of 800 µg mL^‑1, the LDC obtained the highest ABTS^•+ scavenging capacity (96.16±1.36%). Therefore, the LDC produced from dried longan pulp showed strong antioxidant ability and can be used as a primary antioxidant.
In conclusion, these results provided more theoretical guideline for improving the bioavailability of longan, and the development of more deep-processed products such as longan health products.

VI International Symposium on Lychee, Longan and Other Sapindaceae Fruits

T. Wang, K. Wang, L. Zhao, Z. Hu

dried longan, protein-polysaccharide complex, antioxidant activity

https://doi.org/10.17660/ActaHortic.2020.1293.37