Abstract: Two different condensation methods, rotary thin film vacuum evaporation and freeze-thawing, were separately used to condense litchi juice, producing 6 samples. The volatile aromatic compounds in litchi juice and 6 condensed samples were comparatively analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME and GC-MS). The condensed litchi juice samples showed variations in volatile aromatic compound profiles. Compared with freeze-thawing, rotary thin film vacuum evaporation resulted in a reduction of the number of volatile compounds found in condensed litchi juice. The litchi juice condensed by rotary thin film vacuum evaporation had a cooked taste and lacked most of the volatile compounds found in original litchi juice and more volatile compounds were found in the distillate in large quantities. In contrast, the litchi juice condensed by freeze-thawing was found to maintain most of the volatile compounds found in original litchi juice in large quantities and have no cooked taste and all volatile compounds except alcohol were found in the distillate in very small quantities.

Key words: litchi juice, volatile aromatic compounds, rotary thin film vacuum evaporation, freeze-thawing condensation, headspace solid phase micro-extraction, GC-MS