Determination of phenolics, organic acids, minerals and volatile compounds of jujube (Ziziphus jujuba miller) jam produced by under vacuum evaporation compared with open pan method

Abstract

The jujube fruit (Ziziphus jujuba Miller) is used in alternative medicine due to its important bioactive components and is well-suited for jam processing due to its high sugar content. In this study, changes in the chemical and aroma compounds of jujube jams produced using the open-pan (OPJ) and vacuum evaporation (VEJ) methods were determined immediately after production and after a storage period of 4 months. Concentrations of 5-hydroxymethylfurfural (HMF) in the OPJ and VEJ were 13.94 and 1.53 mg/kg initially and 22.63 and 1.66 mg/kg after storage, respectively. Epicatechin was identified as the major phenolic component in jujube fruit and jams. Concentrations of phenolic compounds were higher in the VEJ both before and after storage. It was determined that jujube jam is a good source of the minerals Fe, Ca, Zn, Se, and Cu. Ascorbic acid loss was 86.47% in the OPJ versus 73.32% in the VEJ after production and continued during storage in both jams. Numerous novel aroma compounds that are not found in fresh jujube fruit were produced as a result of the different jam production methods. Significant advantages of the vacuum evaporation process have been determined in the production of jujube jam compared to the open pan process.