Identification of bitter compounds from dried fruit of Ziziphus jujuba cv. Junzao

Abstract

Bitterness in dried jujube fruit can adversely influence its palatability and consumer acceptability. In the present investigation, sensory-guided fractionation with techniques of liquid–liquid extraction, macroporous resin separation, and LC-MS/QTof was applied to identify the bitter compounds in dried jujube fruit (Z. jujuba cv. junzao). The results showed that bitter substances can be successfully extracted from dried jujube fruit using ethanol followed by n-butanol solution. The extract could then be further separated into five fractions by utilizing the macroporous resin separation technique. From this, three bitter fractions were obtained where 35 compounds, including 7 nitrogen compounds, 14 flavonoids, 12 saponins, and 2 fatty acid oxides，were tentatively identified. Based on the structures of these compounds, bitterness generation is likely to result from endogenous phytochemicals of jujube fruit and Maillard reactions during drying processing and also storage.