Pulsed vacuum drying remodels the texture of dried jujube by regulating low-methylesterified pectin and Ca2+-mediated egg-box structures.

Traditional hot air drying (HAD) degraded jujube pectin polysaccharides, leading to a soft texture and lack of crispiness. This study employed pulsed vacuum drying (PVD) to improve the texture of dried jujubes and elucidated the underlying mechanism from the perspective of pectin polysaccharide modification. At the critical time point (MR = 0.4), the "skeletal structure" of jujube slices was formed. At this stage, compared to HAD, PVD retained 41.65% of the relative activity of pectin methylesterase (PME) and extended its activity time by 57.14%, thereby increasing the content of low-methylesterified homogalacturonan (HG). Cellular-level analysis with the oligogalacturonide (OG) probe showed that, compared to HAD, PVD increased low-methylesterified pectin and Ca2+-mediated egg-box structures, boosting calcium-pectate content by 145.53%, which enhanced dried jujube crispiness. Additionally, PVD raised the content and molecular weight of chelate-soluble pectin (CSP) and decreased water-soluble pectin (WSP), significantly improving hardness. This research provided a theoretical basis and technical support for precise texture control in dried jujube processing, aiding the industry's shift toward high-quality, scientifically driven development.