Abstract:

Free and glycosidically-bound volatile compounds were isolated and identified from Huaizhi litchi juice using an Amberlite XAD-2 column and GC-MS. The volatile compounds from the bound fraction were released by hydrolysis with almond β-glucosidase. The results indicated that the differences of aromatic constituents in composition and content between free and bound fraction were significant. Totally 41 and 33 compounds were identified in free and bound fraction, respectively. In the free fraction, the major volatile compounds found were benzenecarboxylic acid, geraniol, 1,2-benzenedicarboxylic acid diisooctyl ester, phenylethyl alcohol, hexadecanoic acid methyl ester, (E)-2-butenedioic acid dimethyl ester , benzyl alcohol, etc. However, in the bound fraction, the latent major volatile compounds found were benzenecarboxylic acid, geraniol, sorbic acid, phenylethyl alcohol, penzyl alcohol, dibutyl phthalate, farnesol, citronellol, etc. In addition, there were 15 compounds that just existed as glycosides, such as 1-undecanol, 1-hexanol, 2-heptanol, 3-octanol, beta-myrcene, benzaldehyde, etc. Especially the contents of typical aroma in litchi such as geraniol, benzyl alcohol, phenylethyl alcohol and citronellol were higher than those in free fraction.

Key words: Huaizhi, Litchi chinensis, free, glycosidically-bound, β- glucosidase, volatile compounds