Effects of pinhole pretreatment on drying and rehydration of whole jujube ( Ziziphus jujuba Mill.)

Pinhole pretreatment is a practical and chemical-free method for enhancing food processing. This study investigated its effects on the drying, rehydration, volumetric shrinkage, color, and texture of whole jujubes. Compared with the untreated samples, shallow and deep pinhole treatments increased the average drying rate by 36.4 ± 6.2% and 75.3 ± 5.1%, respectively. They also improved the rehydration ratio at 25 °C by 27.4 ± 3.0% and 39.8 ± 4.2%, respectively. Increasing the rehydration temperature from 25 °C to 60 °C further improved the rehydration ratio by over 30%. Pinhole pretreatment had no significant effect on the total color difference after drying but reduced both the color difference and browning index after rehydration. It intensified shrinkage during drying while promoting morphological recovery during rehydration. Compared with untreated dried and rehydrated jujubes, pinhole treatment significantly increased their hardness and chewiness but had no significant effect on springiness. Pinhole depth had no significant effect on the textural properties. Overall, controlled pinhole pretreatment offers a simple and chemical-free strategy for accelerating drying and improving the rehydration of whole jujubes, although pinhole depth should be optimized to balance enhanced mass transfer against increased shrinkage and textural changes.