Jujube fruit (Ziziphus jujuba Mill. cv. Junzao) was harvested in December 2020 in Hotan, Xinjiang province (latitude, 79°18′22″; longitude, 37°13′9″). The local climate is temperate continental desert with a high temperature and dry climate, and the annual average rainfall is <50 mm. Approximately 10 kg of dry mature jujube fruit (wet base moisture content, 21%) was collected in foam boxes covered with ice. The samples were sent to the laboratory at Xinjiang Shihezi University within one day. The screened samples were cleaned with double-distilled water (ddH2O), and stored in a dry and odorless cold storage at 4 °C until drying and analysis were complete.
Caffeic acid, ferulic acid, phloroglucinol, cinnamic acid, chlorogenic acid, p-hydroxybenzoic acid, p-coumaric acid, vanillic acid, gallic acid, catechin, protocatechuic acid, epicatechin, rutin, quercetin, and procyanidins B1 and B2 were obtained from Anpel Co. (Shanghai, China). A total of 37 fatty acid mixed standards, 17 amino acid mixed standards, asparagine, glutamine, citrulline, valine, tryptophan, and 21 hydroxyproline and sarcosine standards were obtained from Sigma Aldrich (St. Louis., Mo, USA).
Caffeic acid, ferulic acid, phloroglucinol, cinnamic acid, chlorogenic acid, p-hydroxybenzoic acid, p-coumaric acid, vanillic acid, gallic acid, catechin, protocatechuic acid, epicatechin, rutin, quercetin, and procyanidins B1 and B2 were obtained from Anpel Co. (Shanghai, China). A total of 37 fatty acid mixed standards, 17 amino acid mixed standards, asparagine, glutamine, citrulline, valine, tryptophan, and 21 hydroxyproline and sarcosine standards were obtained from Sigma Aldrich (St. Louis., Mo, USA).