Effect of Drying on the Nutraceutical Quality of Sea Buckthorn ( Hippophae rhamnoides L. ssp. sinensis ) Leaves

The concentrations of total phenolics, carotenoids, and chlorophylls of fresh and dried sea buckthorn leaves were determined. Overall, drying of leaves resulted in a decrease in the concentrations of these phytochemicals. The degree of reduction depended on the drying time, temperature, or specific component type. For the phenolics, a greater reduction in concentration was observed in the leaves dried at higher temperatures (80 °C or 100 °C) for longer times (to equilibrium moisture contents of 1% to 3%) compared with those dried at lower temperatures (50 °C or 60 °C). For the leaves dried to higher final moisture (5% to 8%), all drying temperatures resulted in a similar final phenolic concentration. The carotenoid and chlorophyll concentrations in the leaves decreased with the increasing temperatures. However, higher temperatures such as 80 °C or 100 °C resulted in similar carotenoid and chlorophyll concentrations in the leaves. Nonetheless, dried sea buckthorn leaves were of a high nutraceutical quality comparable to those of frequently consumed vegetables.