Effects of Different Pretreatments on Physicochemical Properties of Pectin from Premna microphylla Turcz Leaves

This paper was to improve raw material utilization and pectin yield,explore the effects of different pretreatments on the physical and chemical properties of pectin from Premna microphylla Turcz leaves,and seek a better pretreatment method. The effects of different pretreatments (steam,microwave,acid soaking,blanching and freezing) on the yield,main compositions,surface morphology and structural properties of pectin were considered. The results showed that the yield of pectin was ranged from 8.95% to 19.32%,the rank was steam > microwaves > acid soaking > non-treatment > blanching > freezing. And the galacturonic acid content was from 69.08% to 89.76%,the rank was steam > microwaves>non-treatment > acid soaking > blanching > freezing. The obtained pectin powder were white by steam,light yellow by microwaves and blanching,and light brown by non-treatment,acid soaking and freezing. The results of scanning electron microscopy indicated that the surface morphology of pectin was rough except for steam. Infrared (IR) spectroscopy discovered that different pretreatments had little impact on the primary functional groups. The pectin by steam pretreatment had the biggest yield and purity,the whitest color,and the smooth surface morphology. The combination of physical and chemical indicators suggested that steam was the optimal pretreatment method for extracting pectin from Premna microphylla Turcz leaves.