Ice cream cone baking: 3. Characterization of residues on baking plates

Analysis of the carbonized deposit on baking plates yielded carbon (58.0%), hydrogen (4.4%), nitrogen (2.2%) and oxygen (25.5%), respectively. Total ash content was 10.7%, comprising 2.4% iron, 2.2% phosphorus, 1.1% magnesium, 0.8% nitrogen, and 0.4% potassium, as determined by argon plasma flame emission spectrophotometry. Surface structure was examined by scanning electron microscopy, and distribution of minerals on the deposit surface was determined by X-ray energy analysis. Results showed that iron migrated into the deposit from the plates. Light microscopy and transmission electron microscopy of new and used plates revealed a change with use in the surface features of the plates, consistent with iron depletion. Scale formation was positively correlated with sugar content and negatively correlated with shortening content of the batter. Nickel or chromium coating of the plate surfaces delayed scale build-up. Heavy scale deposits could be effectively removed by application of a 1:1 mixture of hydrogen peroxide (30%) and concentrated ammonium hydroxide. This mixture should be freshly prepared and used with caution since the reaction may be violent at high temperatures, high pH or in the presence of copper.