Abstract:The effects of different treatment methods on the stability and antioxidant capacity of the bioactive phenolic compounds of litchi pericarps were investigated. Fresh litchi pericarps were open air-dried, steam-blanched for 3 min in combination with hot air oven drying at 60 and 80˝C, and unblanched pericarps were dried in a hot air oven at 40, 60, 70 and 80˝C until equilibrium weight was reached. The total phenolic compounds, flavonoids, anthocyanins, proanthocyanidins and individual procyanidins, and antioxidant activity were analyzed. The combination of blanching and drying at 60˝C significantly (p < 0.05) improved the release of phenolic compounds, individual procyanidins, and the extracts 1 antioxidant capacity compared with the unblanched hot air oven-dried and open air-dried pericarps. Drying of fresh unblanched litchi pericarps in either open air or a hot air oven caused significant losses (p < 0.05) in phenolic compounds and individual procyanidins, leading to a reduction in the antioxidant activity. A similar increase, retention or reduction was reflected in flavonoids, proanthocyanidins and anthocyanins because they are sub-groups of phenolic compounds. Ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picryldydrazyl (DPPH) radical-scavenging capacity of the treated pericarps were significantly correlated (r ě 0.927, p < 0.01) with the total phenolic compounds. Thus, the combination of steam blanching and drying treatments of fresh litchi pericarps could produce a stable and dry litchi pericarp that maintains phenolic compounds and antioxidant capacity as a raw material for further recovery of the phytochemicals.

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