Application of Scanning Electron Microscopy-Energy Dispersive X- Ray Spectrometer to Characterize the Chemical Composition of Deposits on the Surface of Dried Day Lily
HUI-YIN FU1*, MAY-CHING LIN2, JIUNN-HUEI LEE2 AND TZOU-CHI HUANG2
1. Department of Food Science and Technology, Tajen Institute of Technology, 20 Weisin Rd., Yanpu Township, Pingtung County 907, Taiwan (R.O.C.)
2. Department of Food Science, National Pingtung University of Science and Technology, 1 Syuefu Rd., Neipu Township, Pingtung County 912, Taiwan (R.O.C.)
(Received: January 21, 2003; Accepted: June 11, 2003)
ABSTRACT
An innovative and simplified method to characterize the chemical composition of the residual sulphite deposits on dried day lily using scanning electron microscopy- energy dispersive X-ray spectrometer (SEM-EDS) was developed in this study. Granular deposits were observed by SEM on the surface of dried day lily overdosed with sulphiting agents. Laboratory scale model studies showed that soaking in 3% sodium bisulphite without subsequent washing may lead to the accumulation and precipitation of sodium bisulphite crystals. EDS analysis indicated that these deposits are sodium bisulphite. A strong correlation (R2 = 0.8994) was obtained between Sulfur/Carbon ratio calculated from SEM-EDS data and sulfur dioxide concentration determined by modified Monier-Williams method in day lily samples without crystals on the surface.
Key words: day lily, sodium bisulfite, sulfur dioxide, scanning electron microscopy- energy dispersive X ray spectrometer (SEM-EDS)