Organic acid and aromatic compounds create distinctive flavor in the blackening process of jujube.

ABSTRACT

Previous studies demonstrated jujube blackening effectively increased cyclic adenosine phosphate and triterpene acid levels, improving its nutritional value. However, compositional changes during this process require further elucidation. The objective aimed to analyze compositional transformations during this process with SEM, TPA, UPLC-MS, E-nose. Results showed decreased hardness, springiness, and chewiness coupled with increased gumminess over blackening durations. Untargeted omics analysis revealed increases of 2-aminooctadec-8-ene-1,3,4-trioland carbendazim. Targeted organic acid analysis showed initial citric acid accumulation (1481.62 to 1645.78 mg/kg) in the first 24 h, then declines to 1072.96 mg/kg. Meanwhile, oxalic and lactic acids steadily rose, peaking at 96-120 h before slightly decreasing. E-nose analysis implied alterations in organic sulfide aromatics engendered the characteristic flavors. Organic acid fluctuations likely resulted from sugar biotransformation and thermal degradation. These comprehensive analyses demonstrate jujube blackening imparts a rich and unique flavor, providing theoretical support for investigating the mechanisms and products underlying this process.