The present study reports on the preparation processes and characterization of fibers from pineapple cores. The effects of different washing techniques (tap-water and hot-water washing) and particle sizes (0.2, 0.5 and 1 mm) on two important characteristics of dietary fiber, i.e. water holding capacity (WHC) and oil holding capacity (OHC), were investigated. It was found that the washing pre-treatment significantly improved WHC. Meanwhile larger particle sizes of fiber gave better WHC and OHC for all types of fibers. Tap-water washing was the most appropriate pretreatment method compared to hot-water washing and unwashed method. However, there was no difference in morphologies of the fibers before and after being prewashed at different particle sizes. The fiber morphology was preserved best after the drying process using microwave freeze dryer (MFD) and microwave vacuum dryer (MVD). This study demonstrates the potential of pre-treatment and drying methods in functional fiber preparation for food enrichment.