Effects of Superfine Grinding on the Structure, Bioactive Components and Antioxidant Activity of Pineapple Leaf Fiber

Abstract

To investigate the influence of particle size of pineapple leaf fiber (PALF) powders on their structure, bioactive components and antioxidant activities, different sized PALF powders were prepared using superfine grinding. Particle sizes and surface morphology of PALF powders were examined with laser diffraction instrument and scanning electron microscopy (SEM) respectively. Meanwhile, the contents of polyphenols and flavonoids in PALF powders were determined by UV method, and the antioxidant capacity was investigated. During the superfine grinding process, as the time prolonged, the particle size of PALF powders sharply decreased and the surface area increased. When the grinding time reached to 60 min, PALF superfine powder having a median diameter of 18.209 μm was obtained. Scanning electron micrograph displayed that the shape and particle size of superfine powders were uniform. After superfine pulverization, the bioactive components of PALF can be well preserved. The total polyphenols content of PALF superfine powder was 2.347 mg GAE/g DW and the total flavonoids content was 0.227 mg RE/g DW. Therefore, the antioxidant capacity of PALF superfine powder remains high level, including DPPH radical scavenging rate (0.167 mg GAE/g DW), ABTS radical scavenging rate (0.105 mg GAE/g DW) and total antioxidant activity (67.379 unit/g DW). The results demonstrated that PALF superfine powder has good potential to be used in functional food, cosmetics and biomedical materials.